composition of the literature review

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The Research Proposal

83 Components of the Literature Review

Krathwohl (2005) suggests and describes a variety of components to include in a research proposal.  The following sections present these components in a suggested template for you to follow in the preparation of your research proposal.

Introduction

The introduction sets the tone for what follows in your research proposal – treat it as the initial pitch of your idea.  After reading the introduction your reader should:

• Understand what it is you want to do;
• Have a sense of your passion for the topic;
• Be excited about the study´s possible outcomes.

As you begin writing your research proposal it is helpful to think of the introduction as a narrative of what it is you want to do, written in one to three paragraphs.  Within those one to three paragraphs, it is important to briefly answer the following questions:

• What is the central research problem?
• How is the topic of your research proposal related to the problem?
• What methods will you utilize to analyze the research problem?
• Why is it important to undertake this research? What is the significance of your proposed research?  Why are the outcomes of your proposed research important, and to whom or to what are they important?

Note : You may be asked by your instructor to include an abstract with your research proposal.  In such cases, an abstract should provide an overview of what it is you plan to study, your main research question, a brief explanation of your methods to answer the research question, and your expected findings. All of this information must be carefully crafted in 150 to 250 words.  A word of advice is to save the writing of your abstract until the very end of your research proposal preparation.  If you are asked to provide an abstract, you should include 5-7 key words that are of most relevance to your study. List these in order of relevance.

Background and significance

The purpose of this section is to explain the context of your proposal and to describe, in detail, why it is important to undertake this research. Assume that the person or people who will read your research proposal know nothing or very little about the research problem.  While you do not need to include all knowledge you have learned about your topic in this section, it is important to ensure that you include the most relevant material that will help to explain the goals of your research.

While there are no hard and fast rules, you should attempt to address some or all of the following key points:

• State the research problem and provide a more thorough explanation about the purpose of the study than what you stated in the introduction.
• Present the rationale for the proposed research study. Clearly indicate why this research is worth doing.  Answer the “so what?” question.
• Describe the major issues or problems to be addressed by your research. Do not forget to explain how and in what ways your proposed research builds upon previous related research.
• Explain how you plan to go about conducting your research.
• Clearly identify the key or most relevant sources of research you intend to use and explain how they will contribute to your analysis of the topic.
• Set the boundaries of your proposed research, in order to provide a clear focus. Where appropriate, state not only what you will study, but what will be excluded from your study.
• Provide clear definitions of key concepts and terms. As key concepts and terms often have numerous definitions, make sure you state which definition you will be utilizing in your research.

Literature Review

This is the most time-consuming aspect in the preparation of your research proposal and it is a key component of the research proposal. As described in Chapter 5 , the literature review provides the background to your study and demonstrates the significance of the proposed research. Specifically, it is a review and synthesis of prior research that is related to the problem you are setting forth to investigate.  Essentially, your goal in the literature review is to place your research study within the larger whole of what has been studied in the past, while demonstrating to your reader that your work is original, innovative, and adds to the larger whole.

As the literature review is information dense, it is essential that this section be intelligently structured to enable your reader to grasp the key arguments underpinning your study. However, this can be easier to state and harder to do, simply due to the fact there is usually a plethora of related research to sift through. Consequently, a good strategy for writing the literature review is to break the literature into conceptual categories or themes, rather than attempting to describe various groups of literature you reviewed.  Chapter V, “ The Literature Review ,” describes a variety of methods to help you organize the themes.

Here are some suggestions on how to approach the writing of your literature review:

• Think about what questions other researchers have asked, what methods they used, what they found, and what they recommended based upon their findings.
• Do not be afraid to challenge previous related research findings and/or conclusions.
• Assess what you believe to be missing from previous research and explain how your research fills in this gap and/or extends previous research

It is important to note that a significant challenge related to undertaking a literature review is knowing when to stop.  As such, it is important to know how to know when you have uncovered the key conceptual categories underlying your research topic.  Generally, when you start to see repetition in the conclusions or recommendations, you can have confidence that you have covered all of the significant conceptual categories in your literature review.  However, it is also important to acknowledge that researchers often find themselves returning to the literature as they collect and analyze their data.  For example, an unexpected finding may develop as one collects and/or analyzes the data and it is important to take the time to step back and review the literature again, to ensure that no other researchers have found a similar finding.  This may include looking to research outside your field.

This situation occurred with one of the authors of this textbook´s research related to community resilience.  During the interviews, the researchers heard many participants discuss individual resilience factors and how they believed these individual factors helped make the community more resilient, overall.  Sheppard and Williams (2016) had not discovered these individual factors in their original literature review on community and environmental resilience. However, when they returned to the literature to search for individual resilience factors, they discovered a small body of literature in the child and youth psychology field. Consequently, Sheppard and Williams had to go back and add a new section to their literature review on individual resilience factors. Interestingly, their research appeared to be the first research to link individual resilience factors with community resilience factors.

Research design and methods

The objective of this section of the research proposal is to convince the reader that your overall research design and methods of analysis will enable you to solve the research problem you have identified and also enable you to accurately and effectively interpret the results of your research. Consequently, it is critical that the research design and methods section is well-written, clear, and logically organized.  This demonstrates to your reader that you know what you are going to do and how you are going to do it.  Overall, you want to leave your reader feeling confident that you have what it takes to get this research study completed in a timely fashion.

Essentially, this section of the research proposal should be clearly tied to the specific objectives of your study; however, it is also important to draw upon and include examples from the literature review that relate to your design and intended methods.  In other words, you must clearly demonstrate how your study utilizes and builds upon past studies, as it relates to the research design and intended methods.  For example, what methods have been used by other researchers in similar studies?

While it is important to consider the methods that other researchers have employed, it is equally important, if not more so, to consider what methods have not been employed but could be.  Remember, the methods section is not simply a list of tasks to be undertaken. It is also an argument as to why and how the tasks you have outlined will help you investigate the research problem and answer your research question(s).

Tips for writing the research design and methods section:

• Specify the methodological approaches you intend to employ to obtain information and the techniques you will use to analyze the data.
• Specify the research operations you will undertake and he way you will interpret the results of those operations in relation to the research problem.
• Go beyond stating what you hope to achieve through the methods you have chosen. State how you will actually do the methods (i.e. coding interview text, running regression analysis, etc.).
• Anticipate and acknowledge any potential barriers you may encounter when undertaking your research and describe how you will address these barriers.
• Explain where you believe you will find challenges related to data collection, including access to participants and information.

Preliminary suppositions and implications

The purpose of this section is to argue how and in what ways you anticipate that your research will refine, revise, or extend existing knowledge in the area of your study. Depending upon the aims and objectives of your study, you should also discuss how your anticipated findings may impact future research.  For example, is it possible that your research may lead to a new policy, new theoretical understanding, or a new method for analyzing data?  How might your study influence future studies?  What might your study mean for future practitioners working in the field?  Who or what may benefit from your study?  How might your study contribute to social, economic, environmental issues?  While it is important to think about and discuss possibilities such as these, it is equally important to be realistic in stating your anticipated findings.  In other words, you do not want to delve into idle speculation.  Rather, the purpose here is to reflect upon gaps in the current body of literature and to describe how and in what ways you anticipate your research will begin to fill in some or all of those gaps.

The conclusion reiterates the importance and significance of your research proposal and it provides a brief summary of the entire proposed study.  Essentially, this section should only be one or two paragraphs in length. Here is a potential outline for your conclusion:

• Discuss why the study should be done. Specifically discuss how you expect your study will advance existing knowledge and how your study is unique.
• Explain the specific purpose of the study and the research questions that the study will answer.
• Explain why the research design and methods chosen for this study are appropriate, and why other design and methods were not chosen.
• State the potential implications you expect to emerge from your proposed study,
• Provide a sense of how your study fits within the broader scholarship currently in existence related to the research problem.

As with any scholarly research paper, you must cite the sources you used in composing your research proposal.  In a research proposal, this can take two forms: a reference list or a bibliography.  A reference list does what the name suggests, it lists the literature you referenced in the body of your research proposal.  All references in the reference list, must appear in the body of the research proposal.  Remember, it is not acceptable to say “as cited in …”  As a researcher you must always go to the original source and check it for yourself.  Many errors are made in referencing, even by top researchers, and so it is important not to perpetuate an error made by someone else. While this can be time consuming, it is the proper way to undertake a literature review.

In contrast, a bibliography , is a list of everything you used or cited in your research proposal, with additional citations to any key sources relevant to understanding the research problem.  In other words, sources cited in your bibliography may not necessarily appear in the body of your research proposal.  Make sure you check with your instructor to see which of the two you are expected to produce.

Overall, your list of citations should be a testament to the fact that you have done a sufficient level of preliminary research to ensure that your project will complement, but not duplicate, previous research efforts. For social sciences, the reference list or bibliography should be prepared in American Psychological Association (APA) referencing format. Usually, the reference list (or bibliography) is not included in the word count of the research proposal. Again, make sure you check with your instructor to confirm.

An Introduction to Research Methods in Sociology Copyright © 2019 by Valerie A. Sheppard is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Literature Reviews

What this handout is about.

This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Introduction

OK. You’ve got to write a literature review. You dust off a novel and a book of poetry, settle down in your chair, and get ready to issue a “thumbs up” or “thumbs down” as you leaf through the pages. “Literature review” done. Right?

Wrong! The “literature” of a literature review refers to any collection of materials on a topic, not necessarily the great literary texts of the world. “Literature” could be anything from a set of government pamphlets on British colonial methods in Africa to scholarly articles on the treatment of a torn ACL. And a review does not necessarily mean that your reader wants you to give your personal opinion on whether or not you liked these sources.

What is a literature review, then?

A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.

A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

The main focus of an academic research paper is to develop a new argument, and a research paper is likely to contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions.

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone. For professionals, they are useful reports that keep them up to date with what is current in the field. For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper’s investigation. Comprehensive knowledge of the literature of the field is essential to most research papers.

Who writes these things, anyway?

Literature reviews are written occasionally in the humanities, but mostly in the sciences and social sciences; in experiment and lab reports, they constitute a section of the paper. Sometimes a literature review is written as a paper in itself.

Let’s get to it! What should I do before writing the literature review?

If your assignment is not very specific, seek clarification from your instructor:

• Roughly how many sources should you include?
• What types of sources (books, journal articles, websites)?
• Should you summarize, synthesize, or critique your sources by discussing a common theme or issue?
• Should you evaluate your sources?
• Should you provide subheadings and other background information, such as definitions and/or a history?

Find models

Look for other literature reviews in your area of interest or in the discipline and read them to get a sense of the types of themes you might want to look for in your own research or ways to organize your final review. You can simply put the word “review” in your search engine along with your other topic terms to find articles of this type on the Internet or in an electronic database. The bibliography or reference section of sources you’ve already read are also excellent entry points into your own research.

Narrow your topic

There are hundreds or even thousands of articles and books on most areas of study. The narrower your topic, the easier it will be to limit the number of sources you need to read in order to get a good survey of the material. Your instructor will probably not expect you to read everything that’s out there on the topic, but you’ll make your job easier if you first limit your scope.

Keep in mind that UNC Libraries have research guides and to databases relevant to many fields of study. You can reach out to the subject librarian for a consultation: https://library.unc.edu/support/consultations/ .

And don’t forget to tap into your professor’s (or other professors’) knowledge in the field. Ask your professor questions such as: “If you had to read only one book from the 90’s on topic X, what would it be?” Questions such as this help you to find and determine quickly the most seminal pieces in the field.

Consider whether your sources are current

Some disciplines require that you use information that is as current as possible. In the sciences, for instance, treatments for medical problems are constantly changing according to the latest studies. Information even two years old could be obsolete. However, if you are writing a review in the humanities, history, or social sciences, a survey of the history of the literature may be what is needed, because what is important is how perspectives have changed through the years or within a certain time period. Try sorting through some other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to consider what is currently of interest to scholars in this field and what is not.

Strategies for writing the literature review

Find a focus.

A literature review, like a term paper, is usually organized around ideas, not the sources themselves as an annotated bibliography would be organized. This means that you will not just simply list your sources and go into detail about each one of them, one at a time. No. As you read widely but selectively in your topic area, consider instead what themes or issues connect your sources together. Do they present one or different solutions? Is there an aspect of the field that is missing? How well do they present the material and do they portray it according to an appropriate theory? Do they reveal a trend in the field? A raging debate? Pick one of these themes to focus the organization of your review.

Convey it to your reader

A literature review may not have a traditional thesis statement (one that makes an argument), but you do need to tell readers what to expect. Try writing a simple statement that lets the reader know what is your main organizing principle. Here are a couple of examples:

The current trend in treatment for congestive heart failure combines surgery and medicine. More and more cultural studies scholars are accepting popular media as a subject worthy of academic consideration.

Consider organization

You’ve got a focus, and you’ve stated it clearly and directly. Now what is the most effective way of presenting the information? What are the most important topics, subtopics, etc., that your review needs to include? And in what order should you present them? Develop an organization for your review at both a global and local level:

First, cover the basic categories

Just like most academic papers, literature reviews also must contain at least three basic elements: an introduction or background information section; the body of the review containing the discussion of sources; and, finally, a conclusion and/or recommendations section to end the paper. The following provides a brief description of the content of each:

• Introduction: Gives a quick idea of the topic of the literature review, such as the central theme or organizational pattern.
• Body: Contains your discussion of sources and is organized either chronologically, thematically, or methodologically (see below for more information on each).
• Conclusions/Recommendations: Discuss what you have drawn from reviewing literature so far. Where might the discussion proceed?

Organizing the body

Once you have the basic categories in place, then you must consider how you will present the sources themselves within the body of your paper. Create an organizational method to focus this section even further.

To help you come up with an overall organizational framework for your review, consider the following scenario:

You’ve decided to focus your literature review on materials dealing with sperm whales. This is because you’ve just finished reading Moby Dick, and you wonder if that whale’s portrayal is really real. You start with some articles about the physiology of sperm whales in biology journals written in the 1980’s. But these articles refer to some British biological studies performed on whales in the early 18th century. So you check those out. Then you look up a book written in 1968 with information on how sperm whales have been portrayed in other forms of art, such as in Alaskan poetry, in French painting, or on whale bone, as the whale hunters in the late 19th century used to do. This makes you wonder about American whaling methods during the time portrayed in Moby Dick, so you find some academic articles published in the last five years on how accurately Herman Melville portrayed the whaling scene in his novel.

Now consider some typical ways of organizing the sources into a review:

• Chronological: If your review follows the chronological method, you could write about the materials above according to when they were published. For instance, first you would talk about the British biological studies of the 18th century, then about Moby Dick, published in 1851, then the book on sperm whales in other art (1968), and finally the biology articles (1980s) and the recent articles on American whaling of the 19th century. But there is relatively no continuity among subjects here. And notice that even though the sources on sperm whales in other art and on American whaling are written recently, they are about other subjects/objects that were created much earlier. Thus, the review loses its chronological focus.
• By publication: Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on biological studies of sperm whales if the progression revealed a change in dissection practices of the researchers who wrote and/or conducted the studies.
• By trend: A better way to organize the above sources chronologically is to examine the sources under another trend, such as the history of whaling. Then your review would have subsections according to eras within this period. For instance, the review might examine whaling from pre-1600-1699, 1700-1799, and 1800-1899. Under this method, you would combine the recent studies on American whaling in the 19th century with Moby Dick itself in the 1800-1899 category, even though the authors wrote a century apart.
• Thematic: Thematic reviews of literature are organized around a topic or issue, rather than the progression of time. However, progression of time may still be an important factor in a thematic review. For instance, the sperm whale review could focus on the development of the harpoon for whale hunting. While the study focuses on one topic, harpoon technology, it will still be organized chronologically. The only difference here between a “chronological” and a “thematic” approach is what is emphasized the most: the development of the harpoon or the harpoon technology.But more authentic thematic reviews tend to break away from chronological order. For instance, a thematic review of material on sperm whales might examine how they are portrayed as “evil” in cultural documents. The subsections might include how they are personified, how their proportions are exaggerated, and their behaviors misunderstood. A review organized in this manner would shift between time periods within each section according to the point made.
• Methodological: A methodological approach differs from the two above in that the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the “methods” of the researcher or writer. For the sperm whale project, one methodological approach would be to look at cultural differences between the portrayal of whales in American, British, and French art work. Or the review might focus on the economic impact of whaling on a community. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed. Once you’ve decided on the organizational method for the body of the review, the sections you need to include in the paper should be easy to figure out. They should arise out of your organizational strategy. In other words, a chronological review would have subsections for each vital time period. A thematic review would have subtopics based upon factors that relate to the theme or issue.

Sometimes, though, you might need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. Put in only what is necessary. Here are a few other sections you might want to consider:

• Current Situation: Information necessary to understand the topic or focus of the literature review.
• History: The chronological progression of the field, the literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Methods and/or Standards: The criteria you used to select the sources in your literature review or the way in which you present your information. For instance, you might explain that your review includes only peer-reviewed articles and journals.

Questions for Further Research: What questions about the field has the review sparked? How will you further your research as a result of the review?

Begin composing

Once you’ve settled on a general pattern of organization, you’re ready to write each section. There are a few guidelines you should follow during the writing stage as well. Here is a sample paragraph from a literature review about sexism and language to illuminate the following discussion:

However, other studies have shown that even gender-neutral antecedents are more likely to produce masculine images than feminine ones (Gastil, 1990). Hamilton (1988) asked students to complete sentences that required them to fill in pronouns that agreed with gender-neutral antecedents such as “writer,” “pedestrian,” and “persons.” The students were asked to describe any image they had when writing the sentence. Hamilton found that people imagined 3.3 men to each woman in the masculine “generic” condition and 1.5 men per woman in the unbiased condition. Thus, while ambient sexism accounted for some of the masculine bias, sexist language amplified the effect. (Source: Erika Falk and Jordan Mills, “Why Sexist Language Affects Persuasion: The Role of Homophily, Intended Audience, and Offense,” Women and Language19:2).

Use evidence

In the example above, the writers refer to several other sources when making their point. A literature review in this sense is just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence to show that what you are saying is valid.

Be selective

Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the review’s focus, whether it is thematic, methodological, or chronological.

Use quotes sparingly

Falk and Mills do not use any direct quotes. That is because the survey nature of the literature review does not allow for in-depth discussion or detailed quotes from the text. Some short quotes here and there are okay, though, if you want to emphasize a point, or if what the author said just cannot be rewritten in your own words. Notice that Falk and Mills do quote certain terms that were coined by the author, not common knowledge, or taken directly from the study. But if you find yourself wanting to put in more quotes, check with your instructor.

Summarize and synthesize

Remember to summarize and synthesize your sources within each paragraph as well as throughout the review. The authors here recapitulate important features of Hamilton’s study, but then synthesize it by rephrasing the study’s significance and relating it to their own work.

Keep your own voice

While the literature review presents others’ ideas, your voice (the writer’s) should remain front and center. Notice that Falk and Mills weave references to other sources into their own text, but they still maintain their own voice by starting and ending the paragraph with their own ideas and their own words. The sources support what Falk and Mills are saying.

Use caution when paraphrasing

When paraphrasing a source that is not your own, be sure to represent the author’s information or opinions accurately and in your own words. In the preceding example, Falk and Mills either directly refer in the text to the author of their source, such as Hamilton, or they provide ample notation in the text when the ideas they are mentioning are not their own, for example, Gastil’s. For more information, please see our handout on plagiarism .

Revise, revise, revise

Draft in hand? Now you’re ready to revise. Spending a lot of time revising is a wise idea, because your main objective is to present the material, not the argument. So check over your review again to make sure it follows the assignment and/or your outline. Then, just as you would for most other academic forms of writing, rewrite or rework the language of your review so that you’ve presented your information in the most concise manner possible. Be sure to use terminology familiar to your audience; get rid of unnecessary jargon or slang. Finally, double check that you’ve documented your sources and formatted the review appropriately for your discipline. For tips on the revising and editing process, see our handout on revising drafts .

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Jones, Robert, Patrick Bizzaro, and Cynthia Selfe. 1997. The Harcourt Brace Guide to Writing in the Disciplines . New York: Harcourt Brace.

Lamb, Sandra E. 1998. How to Write It: A Complete Guide to Everything You’ll Ever Write . Berkeley: Ten Speed Press.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Troyka, Lynn Quittman, and Doug Hesse. 2016. Simon and Schuster Handbook for Writers , 11th ed. London: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

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How To Structure Your Literature Review

3 options to help structure your chapter.

By: Amy Rommelspacher (PhD) | Reviewer: Dr Eunice Rautenbach | November 2020 (Updated May 2023)

Writing the literature review chapter can seem pretty daunting when you’re piecing together your dissertation or thesis. As  we’ve discussed before , a good literature review needs to achieve a few very important objectives – it should:

• Demonstrate your knowledge of the research topic
• Identify the gaps in the literature and show how your research links to these
• Provide the foundation for your conceptual framework (if you have one)
• Inform your own  methodology and research design

To achieve this, your literature review needs a well-thought-out structure . Get the structure of your literature review chapter wrong and you’ll struggle to achieve these objectives. Don’t worry though – in this post, we’ll look at how to structure your literature review for maximum impact (and marks!).

But wait – is this the right time?

Deciding on the structure of your literature review should come towards the end of the literature review process – after you have collected and digested the literature, but before you start writing the chapter. 

In other words, you need to first develop a rich understanding of the literature before you even attempt to map out a structure. There’s no use trying to develop a structure before you’ve fully wrapped your head around the existing research.

Equally importantly, you need to have a structure in place before you start writing , or your literature review will most likely end up a rambling, disjointed mess. 

Importantly, don’t feel that once you’ve defined a structure you can’t iterate on it. It’s perfectly natural to adjust as you engage in the writing process. As we’ve discussed before , writing is a way of developing your thinking, so it’s quite common for your thinking to change – and therefore, for your chapter structure to change – as you write. 

Need a helping hand?

Like any other chapter in your thesis or dissertation, your literature review needs to have a clear, logical structure. At a minimum, it should have three essential components – an  introduction , a  body   and a  conclusion . 

Let’s take a closer look at each of these.

1: The Introduction Section

Just like any good introduction, the introduction section of your literature review should introduce the purpose and layout (organisation) of the chapter. In other words, your introduction needs to give the reader a taste of what’s to come, and how you’re going to lay that out. Essentially, you should provide the reader with a high-level roadmap of your chapter to give them a taste of the journey that lies ahead.

Here’s an example of the layout visualised in a literature review introduction:

Your introduction should also outline your topic (including any tricky terminology or jargon) and provide an explanation of the scope of your literature review – in other words, what you  will   and  won’t   be covering (the delimitations ). This helps ringfence your review and achieve a clear focus . The clearer and narrower your focus, the deeper you can dive into the topic (which is typically where the magic lies). 

Depending on the nature of your project, you could also present your stance or point of view at this stage. In other words, after grappling with the literature you’ll have an opinion about what the trends and concerns are in the field as well as what’s lacking. The introduction section can then present these ideas so that it is clear to examiners that you’re aware of how your research connects with existing knowledge .

2: The Body Section

The body of your literature review is the centre of your work. This is where you’ll present, analyse, evaluate and synthesise the existing research. In other words, this is where you’re going to earn (or lose) the most marks. Therefore, it’s important to carefully think about how you will organise your discussion to present it in a clear way. 

The body of your literature review should do just as the description of this chapter suggests. It should “review” the literature – in other words, identify, analyse, and synthesise it. So, when thinking about structuring your literature review, you need to think about which structural approach will provide the best “review” for your specific type of research and objectives (we’ll get to this shortly).

There are (broadly speaking)  three options  for organising your literature review.

Option 1: Chronological (according to date)

Organising the literature chronologically is one of the simplest ways to structure your literature review. You start with what was published first and work your way through the literature until you reach the work published most recently. Pretty straightforward.

The benefit of this option is that it makes it easy to discuss the developments and debates in the field as they emerged over time. Organising your literature chronologically also allows you to highlight how specific articles or pieces of work might have changed the course of the field – in other words, which research has had the most impact . Therefore, this approach is very useful when your research is aimed at understanding how the topic has unfolded over time and is often used by scholars in the field of history. That said, this approach can be utilised by anyone that wants to explore change over time .

For example , if a student of politics is investigating how the understanding of democracy has evolved over time, they could use the chronological approach to provide a narrative that demonstrates how this understanding has changed through the ages.

Here are some questions you can ask yourself to help you structure your literature review chronologically.

• What is the earliest literature published relating to this topic?
• How has the field changed over time? Why?
• What are the most recent discoveries/theories?

In some ways, chronology plays a part whichever way you decide to structure your literature review, because you will always, to a certain extent, be analysing how the literature has developed. However, with the chronological approach, the emphasis is very firmly on how the discussion has evolved over time , as opposed to how all the literature links together (which we’ll discuss next ).

Option 2: Thematic (grouped by theme)

The thematic approach to structuring a literature review means organising your literature by theme or category – for example, by independent variables (i.e. factors that have an impact on a specific outcome).

As you’ve been collecting and synthesising literature , you’ll likely have started seeing some themes or patterns emerging. You can then use these themes or patterns as a structure for your body discussion. The thematic approach is the most common approach and is useful for structuring literature reviews in most fields.

For example, if you were researching which factors contributed towards people trusting an organisation, you might find themes such as consumers’ perceptions of an organisation’s competence, benevolence and integrity. Structuring your literature review thematically would mean structuring your literature review’s body section to discuss each of these themes, one section at a time.

Here are some questions to ask yourself when structuring your literature review by themes:

• Are there any patterns that have come to light in the literature?
• What are the central themes and categories used by the researchers?
• Do I have enough evidence of these themes?

PS – you can see an example of a thematically structured literature review in our literature review sample walkthrough video here.

Option 3: Methodological

The methodological option is a way of structuring your literature review by the research methodologies used . In other words, organising your discussion based on the angle from which each piece of research was approached – for example, qualitative , quantitative or mixed  methodologies.

Structuring your literature review by methodology can be useful if you are drawing research from a variety of disciplines and are critiquing different methodologies. The point of this approach is to question  how  existing research has been conducted, as opposed to  what  the conclusions and/or findings the research were.

For example, a sociologist might centre their research around critiquing specific fieldwork practices. Their literature review will then be a summary of the fieldwork methodologies used by different studies.

Here are some questions you can ask yourself when structuring your literature review according to methodology:

• Which methodologies have been utilised in this field?
• Which methodology is the most popular (and why)?
• What are the strengths and weaknesses of the various methodologies?
• How can the existing methodologies inform my own methodology?

3: The Conclusion Section

Once you’ve completed the body section of your literature review using one of the structural approaches we discussed above, you’ll need to “wrap up” your literature review and pull all the pieces together to set the direction for the rest of your dissertation or thesis.

The conclusion is where you’ll present the key findings of your literature review. In this section, you should emphasise the research that is especially important to your research questions and highlight the gaps that exist in the literature. Based on this, you need to make it clear what you will add to the literature – in other words, justify your own research by showing how it will help fill one or more of the gaps you just identified.

Last but not least, if it’s your intention to develop a conceptual framework for your dissertation or thesis, the conclusion section is a good place to present this.

Example: Thematically Structured Review

In the video below, we unpack a literature review chapter so that you can see an example of a thematically structure review in practice.

Let’s Recap

In this article, we’ve  discussed how to structure your literature review for maximum impact. Here’s a quick recap of what  you need to keep in mind when deciding on your literature review structure:

• Just like other chapters, your literature review needs a clear introduction , body and conclusion .
• The introduction section should provide an overview of what you will discuss in your literature review.
• The body section of your literature review can be organised by chronology , theme or methodology . The right structural approach depends on what you’re trying to achieve with your research.
• The conclusion section should draw together the key findings of your literature review and link them to your research questions.

If you’re ready to get started, be sure to download our free literature review template to fast-track your chapter outline.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

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27 Comments

Great work. This is exactly what I was looking for and helps a lot together with your previous post on literature review. One last thing is missing: a link to a great literature chapter of an journal article (maybe with comments of the different sections in this review chapter). Do you know any great literature review chapters?

I agree with you Marin… A great piece

I agree with Marin. This would be quite helpful if you annotate a nicely structured literature from previously published research articles.

Awesome article for my research.

I thank you immensely for this wonderful guide

It is indeed thought and supportive work for the futurist researcher and students

Very educative and good time to get guide. Thank you

Great work, very insightful. Thank you.

Thanks for this wonderful presentation. My question is that do I put all the variables into a single conceptual framework or each hypothesis will have it own conceptual framework?

Thank you very much, very helpful

This is very educative and precise . Thank you very much for dropping this kind of write up .

Pheeww, so damn helpful, thank you for this informative piece.

I’m doing a research project topic ; stool analysis for parasitic worm (enteric) worm, how do I structure it, thanks.

comprehensive explanation. Help us by pasting the URL of some good “literature review” for better understanding.

great piece. thanks for the awesome explanation. it is really worth sharing. I have a little question, if anyone can help me out, which of the options in the body of literature can be best fit if you are writing an architectural thesis that deals with design?

I am doing a research on nanofluids how can l structure it?

Beautifully clear.nThank you!

Lucid! Thankyou!

Brilliant work, well understood, many thanks

I like how this was so clear with simple language 😊😊 thank you so much 😊 for these information 😊

Insightful. I was struggling to come up with a sensible literature review but this has been really helpful. Thank you!

You have given thought-provoking information about the review of the literature.

Thank you. It has made my own research better and to impart your work to students I teach

I learnt a lot from this teaching. It’s a great piece.

I am doing research on EFL teacher motivation for his/her job. How Can I structure it? Is there any detailed template, additional to this?

You are so cool! I do not think I’ve read through something like this before. So nice to find somebody with some genuine thoughts on this issue. Seriously.. thank you for starting this up. This site is one thing that is required on the internet, someone with a little originality!

I’m asked to do conceptual, theoretical and empirical literature, and i just don’t know how to structure it

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

Prevent plagiarism, run a free check.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 

How to write a good literature review 

• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• How to write a literature review faster with Paperpal? 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

1. Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 

2. Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 

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3. Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 

4. Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 

5. Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 

6. Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

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Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

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Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

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How to write a literature review faster with Paperpal?

Paperpal, an AI writing assistant, integrates powerful academic search capabilities within its writing platform. With the Research feature, you get 100% factual insights, with citations backed by 250M+ verified research articles, directly within your writing interface with the option to save relevant references in your Citation Library. By eliminating the need to switch tabs to find answers to all your research questions, Paperpal saves time and helps you stay focused on your writing.   

Here’s how to use the Research feature:  

• Ask a question: Get started with a new document on paperpal.com. Click on the “Research” feature and type your question in plain English. Paperpal will scour over 250 million research articles, including conference papers and preprints, to provide you with accurate insights and citations. 
• Review and Save: Paperpal summarizes the information, while citing sources and listing relevant reads. You can quickly scan the results to identify relevant references and save these directly to your built-in citations library for later access. 
• Cite with Confidence: Paperpal makes it easy to incorporate relevant citations and references into your writing, ensuring your arguments are well-supported by credible sources. This translates to a polished, well-researched literature review. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a good literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. By combining effortless research with an easy citation process, Paperpal Research streamlines the literature review process and empowers you to write faster and with more confidence. Try Paperpal Research now and see for yourself.  

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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3 Literature Review

Charitianne Williams

By the end of this chapter, you will be able to do the following:

• Understand the purpose and function of a literature review.
• Structure a literature review according to basic genre expectations.
• Synthesize ideas from multiple sources using a synthesis matrix.
• Choose between narrative or parenthetical citation and direct quoting, or paraphrase with intent and purpose.

I. Introduction

The purpose of a literature review is just that—it reviews. This means that literature reviews examine a text after it was produced, with all the benefits that hindsight allows a reader. In popular culture, we commonly review movies, restaurants, vacation spots, products, etc. In those reviews, you look back at the single thing you are reviewing and your experience with it. You focus on the strengths and weaknesses of your experience and judge the experience as positive or negative while recommending or not recommending the place or product and explaining why.

An academic literature review does something different, although some of the skills and strategies you use remain the same. The job of a literature review is to examine a collection of research or scholarship (not a single thing or text) on a given topic and show how that scholarship fits together. Literature reviews summarize, describe, evaluate, and synthesize the work of other authors and researchers while looking for common trends/patterns, themes, inconsistencies, and gaps in this previous research. The main strategy writers of a literature review use is synthesis.

SYNTHESIS: the combination of ideas and elements to form a complete system or theory.

A good metaphor for synthesis is cooking! Imagine the ingredients for a loaf of bread laid out on a kitchen cabinet. Each ingredient—eggs, milk, flour, sugar, salt, yeast—have their own purpose and can be combined in different ways to form food other than bread. Knowing all of those individual attributes that make an egg an egg, or the difference between yeast and flour, is what makes you a chef. When you combine all these ingredients according to the recipe, you get something different than all the ingredients on their own: and most of us would rather eat a slice of bread than a spoonful of flour. The product of synthesis is like bread. Synthesis takes a list of ingredients and makes them into something more than the ingredients alone.

Usually, the writers of a literature review will start with a question that they want to answer through informed and research-based evidence gathered while reading others’ work on related topics. The “thesis” or controlling idea of a literature review may be that same question ( “This review seeks to answer…” ) or it may be a statement describing the reviewed research. The thesis reflects the purpose of the literature review as a genre and is different from the thesis you will write for the research paper that argues a claim or asserts a new idea.

Example 3.1: Look at this thesis statement taken from the introduction of a literature review in environmental psychology on the relationship between “nature sounds” and restorative environments:

From this example, we can learn many things about literature reviews:

• They are explicit and focused on their topic. The opening states an observable truth about the current research ( emphasizes nature ), is followed by a general condition ( positive psychological experiences) within that research, and then finally focuses on describing how a particular outcome is achieved (listening to nature sounds is restorative).
• They seek to pre vent or eliminate misunderstanding. Note the use of specialized key terms, exacting transitional phrases, and meaningful verbs in the thesis such as “ restorative environments,” “in particular,” and “ generate .”
• They seek to forward understanding. In other words, literature reviews examine and link together evidence described and validated in the research of others so a reader can learn how a field is developing. ( Research seems to agree that nature sounds can relieve stress and fatigue–this review will examine that conclusion so readers can understand/ build on how and why.)

Moving from the beginning to the very end of the literature review, we can also learn many things about literature reviews from the sources used. Think of each text listed in the References section of a literature review as contributing pieces to a gigantic puzzle.

Example 3.2: Look at the first three articles listed in the References for the article excerpted above:

Abbott, L. C., Taff, D., Newman, P., Benfield, J. A., and Mowen, A. J. (2016). The influence of natural sounds on attention restoration. J. Park Recreation Adm. 34, 5–15. doi: 10.18666/JPRA-2016-V34-I3-6893

Aletta, F., and Kang, J. (2019). Promoting healthy and supportive acoustic environments: going beyond the quietness. Int. J. Environ. Res. Public Health 16:4988. doi: 10.3390/ijerph16244988

Aletta, F., Oberman, T., and Kang, J. (2018). Associations between positive health-related effects and soundscapes perceptual constructs: a systematic review. Int. J. Environ. Res. Public Health 15:2392. doi: 10.3390/ijerph15112392

None of these sources are exactly the same. One focuses on sound and attention, the next two on sound and health, and none of them are quite the same as sound and restoration —but they are all pieces of the puzzle that give a full understanding of how sound and restorative environments relate.

As the author of the literature review, it is your job to join the pieces together, giving your reader a complete picture of what researchers know about your topic.

Literature reviews are an indispensable tool for researchers. Instead of having to read dozens of articles on a topic, a researcher could instead read a literature review that synthesizes what is known and puts each piece of scholarship into conversation with the others. This could be not only quicker, but also more valuable.

Have you heard the saying that the whole is more than the sum of its parts? The knowledge constructed by a well-written literature review often outweighs the knowledge constructed by simply reading each article in the References section on its own because the author of a literature review processes and analyzes the information for the reader.

Literature reviews occur in two general forms—as a background section in a scholarly work or as a stand-alone genre in and of itself. In both situations, the basic purpose and structure of the literature review is similar: it is the length and the scope that varies. For example, consider the previous chapter, the Proposal. In most proposals, you will want to convince your audience that you are informed on the background of your topic—a literature review is how you would do that. Since a proposal is commonly a short text, you do not have the space to summarize every piece of research. You must select an important set and synthesize that information into a small section signaling your expertise.

On the other hand, consider a professional journal intended to keep its readers up to date on new technologies and findings in a specific field or career. New ideas and discoveries are emerging every day, and it can be difficult to stay on top of all of these new findings, understand how they fit together, and also keep track of your own career responsibilities! A magazine might hire an author to read all the new research on a specific topic and synthesize it into a single article, a state-of-the-art review, so that practitioners in a field can read a single 25-page article instead of 100 25-page articles.

More Resources 3.1: Literature Reviews

II. Rhetorical Considerations: Voice

Using the scholarship of other writers and researchers is one of the things that differentiates academic writing from other types of writing. Using others’ scholarship in a meaningful way that creates new knowledge without mischaracterizing the original findings takes effort, attention, and usually several rounds of revision and rewriting. One of the issues is voice , which refers to the attitude and tone of a text—think of it as what the text “sounds like” in your head as you read it. Voice is an important element of cohesion , or what some people think of as “flow.” Creating a consistent voice in the mind of your reader helps them fit all the information in a text together in the way the author intends. Check out this advice from APAstyle.org about academic style and voice.

Think back to your annotated bibliography and how you created your summaries. You probably used key terms from the original authors’ texts, but because you had to take whole articles and restate the meaning in a short paragraph, there wasn’t room to just repeat the words of the original author. So you had to write the summaries in your voice . If you used those key terms correctly and in ways similar to original authors, those key terms probably did not interfere with cohesiveness and voice. However, in the literature review, you have many more voices to synthesize than you did to summarize in the annotated bibliography. Maintaining a consistent and cohesive voice will be challenging. An important way to maintain voice is through paraphrasing, discussed later in this chapter.

More Resources 3.2: Transitions

Another important way to maintain cohesion is through the use of metadiscourse (see Chapter 2) and transitional phrases. See this link for the use and meaning of transitional phrases, sometimes called signposts .

III. The Literature Review Across the Disciplines

Example 3.3: Academic and Professional Examples

Structure of Literature Reviews

While the details vary across disciplines, all literature reviews tend to have similar basic structure. The introduction of a literature review informs the reader on the topic by defining key terms, citing key researchers or research periods in the field, and introducing the main focus of the review in a descriptive thesis statement. The introduction also explains the organization of the review. In a literature review, you organize your discussion of the research by topic or theme— not article or author. This is in direct contrast to the annotated bibliography, which is often the first step in the writing process for a literature review.

In the annotated bibliography, you organize your entries in alphabetical order by authors’ last names. Each annotation is directly connected to a single text. A literature review is connected to a collection of texts, and therefore must be organized in a way that reflects this.

Example 3.4: Let’s examine the full paragraph that the thesis statement we analyzed earlier came from:

A systematic review by Aletta et al. (2018) has identified links between positive urban soundscapes (which may also include nature sounds) and health and well-being, including stress recovery. Given the emphasis on nature w ithin restorative environments (see Hartig et al., 2014 ), the present narrative literature review focuses on evidence for positive psychological experiences of nature sounds and soundscapes specifically, and in particular how listening to these can generate perceptions and outcomes of restoration from stress and fatigue. This review has five key objectives, summarized in Figure 1 [in the article] . First, it explores literature regarding the impact of nature sounds on perceptions and experiences of wider natural environments. Second, it examines evidence regarding cognitive and affective appraisals of nature sounds and their contributions to overall perceptions of restorative environments. Third, literature regarding restorative outcomes in response to nature sounds is assessed. Fourth, the relevance of key restoration theories to this top ic is examined and areas where these theories are limited are identified. Fifth, a possible new theoretical area of interest—semantic associations with nature—is discussed and exemplified by recent acoustics research (Ratcliffe, 2021, emphasis added).

Notice how the thesis statement (in bold ) is followed by an explicit description of the five key objectives—which correspond to the titles (usually called headings ) of the five major sections of the body of the literature review. The introduction basically outlines the body of the literature review to make it easier for a researcher to find the specific information they are looking for. What follows each of these headings is an analysis and synthesis of the topic described in the heading—which is what we mean when we say a literature review is organized by topic.

Example 3.5: See how the body sections of a literature review synthesize research and evidence in relation to a focused topic. Read this example taken from a literature review in another discipline, nursing.

The introduction states that the review’s purpose is to understand the issues facing nurses in situations such as the COVID-19 pandemic. The researchers found several themes in the research that all contributed to nurses’ experiences. This paragraph describes one of those themes which the authors label “Professional collegiality”:

3.2.2. Professional collegiality

Professional camaraderie amongst nursing colleagues working during a pandemic was high (Ives et al., 2009, Kim, 2018, Liu a nd Liehr , 2009). Nurses acknowledged the importance of caring for their co-workers and in sharing the load. Some nurses associated the experience with working on a battlefield, whereby they worked together as a team protecting one another (Chung et al., 20 05, Kang et al., 2018, Liu and Liehr , 2009). Appreciation of their nursing colleagues was demonstrated through sharing their experiences, willingness to work together and encouraging a team spirit (Shih et al., 2007, Chung et al., 2005, Chiang et al., 2007 ). (Ratcliffe, 2021, p.4)

In this single paragraph, there are seven different research articles cited, and some of them are cited twice. There is no way to write a coherent paragraph summarizing seven different research articles at once—instead, the authors of this paragraph reviewed what the researchers said about collegiality, found where their findings pointed in the same direction, and put those connections into their own words. This is the importance of the review’s body section: it is here where you really dig into the content, meaning, and implications of the scholarship you are discussing.

The end of a literature review looks different from the one- or two-paragraph conclusion we are used to in other texts. The end is often made up of multiple sections, each with a slightly different purpose, although all are probably recognizable to you. A “Discussion” section is almost always present, where the author summarizes the most important findings of each section. In most cases, the “Discussion” section does not contain new information, but ties the different body sections together in ways that provide a deeper analysis.

The end of a literature review may also contain an “Implications for Future Research” or “Resolution” after the Discussion—sometimes this final section is even called “Conclusion.” What this last section looks like is often dependent upon the type of review you are writing, and whether the review is standing alone as a complete text or part of a larger project.

In any situation, across all disciplines, it is important to understand how your literature review is meant to inform the reader and what kind of review is appropriate for the context, in order to decide how you should structure the beginning and end of your review.

Types of Literature Reviews

There are different types of literature reviews, although in undergraduate study the Traditional or Narrative Review is most common. Narrative reviews are somewhat exploratory in their content—in a narrative review you are synthesizing the results of specific texts selected for their connection to your topic. Narrative reviews almost always end with a section describing areas for future research if they are a stand-alone text, or a section describing why the author’s research is so needed if part of a larger research article. The chart below outlines the key differences between three major literature review types. Notice that each type has a slightly different purpose. You might think about which type best fits your project as you read.

Table 3.1: Types of Literature Reviews

More Resources 3.3: Literature Review Structures

IV. Research Strategies: Developing a Methodology

Systematic and scoping reviews should always contain a Research Methodology that explains to your reader exactly how you found the research you are reviewing. Often Narrative Reviews will also contain a research methodology, although it will be slightly different since they are not comprehensive reviews, meaning, they do not attempt to find all the research on a topic—by design, they cover only a specific portion. Even if you are not required to write up your methodology, you need clear research strategies to find the appropriate scholarship for your literature review.

Example 3.6: Check out this excerpt from the methods sections from a psychology literature review. Note how the authors clearly describe what types of sources they’ll be using as well as their steps throughout the research process.

Drawing on individual case studies, archival reports, correlational studies, and laboratory and field experiments, this monograph scrutinizes a sequence of events during which confessions may be obtained from criminal suspects and used as evidence. First, we examine the pre-interrogation interview, a process by which police …( Kassin and Gudjonsson , 2004, p.33)

Example 3.7: Here is another example from the field of education. In it the authors describe two separate searches they performed to gather the literature—the first search used key terms they decided upon before reading any scholarship, and the second search used the terms that they found were common to that first set of texts (see more about key terms here and in the Annotated Bibliography chapter).

We conducted two rounds of literature searches, utilizing the following databases: World CAT (general search), EB SCO Academic Search Complete, EBSCO Education Source, and Linguistics and Language Behavior Abstracts (ProQuest). In the first round, we searched using every possible combination of the following terms: ‘race,’ ‘language teaching,’ ‘ethnicity,’ ‘language p edagogy,’ ‘Whiteness,’ ‘racialized,’ ‘antiracism,’ and ‘ nativeness .’ For the second round of our literature search, we searched using terms that we saw emerging from the literature such as ‘racial identities of language learners,’ ‘racial identities of lan guage teachers,’ ‘language varieties and language teaching,’ ‘race and language teacher education,’ ‘race and educational policy,’ ‘race and language programs,’ and ‘race and language curriculum’ and also repeated our earlier searches in order to keep the literature updated. (Von Esch et al., 2020, p. 392)

No matter the type of research (see a description of qualitative vs. quantitative research ), the specific genres (see descriptions of academic research genres ), or the time frame (see a discussion on the importance of publication date ) you use for your review, it is important to think through the options, make a decision, and incorporate all your research knowledge—use of key terms, use of subject filters, use of specialized databases, etc.—into a coherent and meaningful process that results in the best scholarship for your inquiry and review.

Here’s a video to help you get started on using databases for research:

Library Referral: Connecting the Conversation with Scholarly Sources and Beyond​

(by Annie R. Armstrong)

Research involves drawing from numerous voices from a range of source types. The sources you choose to include in your conversation are context-specific and might vary depending on your topic or the parameters of your assignment. Review your assignment description and talk to your instructor about guidelines. While most research papers emphasize scholarly sources, expertise isn’t always equated with scholarliness and you might want to branch out. For example, a research paper focusing on exploitation of Native American land and communities by the mining industry should make some attempt to include sources generated by the communities under discussion, especially if their point of view is not represented in the peer-reviewed, scholarly sources you’ve found. Think about who the stakeholders are as related to various aspects of your topic and how you can tap into their voices through available resources. You may want to consult a librarian about this.

The chart below summarizes the breadth of source types available through library websites versus the open web:

Table 3.2: Scholarly Sources and Beyond

V. Reading Strategies: Intertextuality and Graphic Organizers

Typically we think of reading as something we do to learn the content of a text—and this is absolutely true! But true understanding means knowing the relationships between and impact of separate but related topics, which might mean understanding how different texts—generally focused on one topic—overlap or differ.

Intertextuality refers to the connections that exist between texts. Intertextuality as a reading strategy means looking for the connections between the text you are reading and others you have already read; anticipating connections with other texts that you have not yet read, but plan to; as well as connections to whole disciplines, fields, and social phenomena. Reading for intertextuality means looking for opportunities to connect texts with each other, and keeping track of those connections in a productive way.

This means note-taking is essential to intertextual reading. Once you have thought carefully about why you are reading a text, what types of information to look for, and what you will do with that information, you can better decide how to keep track of that information. In regards to literature reviews, one type of graphic organizer dominates: the Synthesis Matrix.

The synthesis matrix is a way to keep track of the themes, concepts, and patterns that are emerging from your reading—NOT all the individual content of each article. This is important, yes, and you will need the citations, but literature reviews move one step further into the topic than simply identifying the pieces. You will need to synthesize.

If you have an annotated bibliography of sources already, it is the perfect way to start your synthesis matrix. An annotated bibliography is often the first step in preparing for a literature review, and is quite similar to an ingredient list, if we are using the metaphor from the introduction. (For a detailed description of how to write an annotated bibliography, see Chapter 1 ).

In your annotations, you will have selected the most important information that text supplies in relation to your topic. For an example, let’s take the Conference on College Composition and Communication’s statement “ Students’ Right to Their Own Language ,” which contains two annotated bibliographies. The second uses more recent sources and looks most like the annotated bibliographies you will write as a student, so let’s start there.

Example 3.8: Here are three annotations from that bibliography. As you read, take notice of the different highlighted colors. Phrases italicized and highlighted green identify ideas related to linguistic identity , phrases bolded and highlighted in blue identify concepts related to grammar analysis , and phrases underlined and highlighted orange identify groups and ideas related to educational objectives :

Fought, Carmen. Chicano English in Context. New York: Palgrave Macmillan, 2003.

Based primarily on data collected from adolescent and young adult native speakers in Los Angeles , this book is a comprehensive sociolinguistic study of language and language change in Latino/a communities. It provides the basics of Chicano English (CE) structure (phonology, syntax, and semantics) and its connection to the social and cultural identity of its speakers, along with detailed analyses of particular sociolinguistic variables. Emphasis is given to the historical, social, and linguistic contexts of CE. In addition, the differences between native and non-native CE speakers are covered. A final chapter discusses the future of research on CE.

Lippi-Green, Rosina. English with an Accent: Language, Ideology, and Discrimination in the United States . London and New York: Routledge, 1997.

The author examines linguistic facts about the structure and function of language , explores commonly held myths about language, and develops a model of “the language subordination process.” Then, using a case-study approach, she applies the model to specific institutional practices (e.g., in education, news media, business) to show how false assumptions about language lead to language subordination. The author analyzes specific groups and individuals (speakers of African American English, Southern U.S. English, and the foreign-language accent of Latinos and Asian Americans) and discusses why and how some embrace linguistic assimilation while others resist it.

Nero, Shondel J. Englishes in Contact: Anglophone Caribbean Students in an Urban College. Cresskill, NJ: Hampton Press, 2001.

This qualitative study of four anglophone Caribbean students at a New York City college offers an in-depth examination of the students’ written and spoken language and the challenges faced by both students and teachers as such students acquire academic literacy. Case studies of the four participants include excerpts from tape-recorded interviews, which reflect their linguistic self-perception, and sociolinguistic and educational experiences in their home countries and in New York City. Samples of their college writing over four semesters are represented and analyzed on morphosyntactic and discourse levels to determine the patterns that emerge when Creole English speakers attempt to write Standard Written English. Related issues such as language and identity , language attitudes, and educational responses to ethnolinguistic diversity are also discussed.

Once you have identified a concept like “language and identity” for your literature review, you can start getting “intertextual”! Review your other annotated sources and your new sources for their discussion of language and identity, as well as parallel concepts—what else do researchers address when they discuss language and identity? What do they discuss instead? Go back to the methods you used to come up with key terms for your literature search—the same strategies now apply to your reading. Also look for “umbrella” concepts, patterns in methodologies—anything that emerges while you read intertextually, focusing on the text in front of you while also remembering all the others you read before. Look for the themes in your annotated bibliography and keep track of the page numbers where these themes appear—plan to go back to those pages several times as you write your literature review.

This is a different type of reading than you did for the annotated bibliography, and might mean you go back and reread your sources several times in this new way—don’t think of this as just repeating labor you have already performed. This is new work, designed to uncover new things in the research. Re-reading articles multiple times is something all serious writers do, and something you should do, too. It isn’t redundant, it is recur sive .

Table 3.3: Synthesis Matrix for Individuals’ Choices in Linguistic Identity

Put your sources into conversations around your themes, as shown in the table above. Notice that the top row names the themes covered in that column, put into original wording similar, but not identical, to the wording in the annotated bibliographies. Not every source will address every topic—not every article is the same. The last row starts to describe what is happening in each column across the whole collection of texts. In this way, your synthesis matrix takes the ingredient list provided by the annotated bibliography and makes it into a recipe for your final product—the literature review.

More Resources 3.4: Synthesis Matrix

VI. Writing Strategies: Citation, Quotation, and Paraphrase

Citation is when you use the work of other authors in your writing and mark that portion of your writing so your reader understands what idea is being “borrowed.” Citation also tells your reader where they could find that original idea in the original text, and how your text fits together with the web of other texts related to your topic: in other words, citations help create intertextuality. A citation placed in your sentences should refer directly to the full bibliographic information in your Works Cited or References page.

As you read in Chapter 1, there are different styles of citation including AMA, APA, CMS, and MLA. You can refer back to that chapter for a more detailed explanation of each. In this section, we’ll cover the basics that are common to citation practices. Most academic styles use the original author’s last name as the central part of the in-text citation, since References pages usually list cited works alphabetically by last name, but some use footnotes or endnotes instead, listing works in the order they were cited. It is important to know which academic style you are using for your literature review so that you can make the right choice.

In-text citation takes one of two forms: parenthetical or narrative. In a narrative citation the author of the original work is mentioned in the sentence.

Example 3.9: Here’s an example taken from the introduction of the same literature review discussed in the Research Strategies: Developing a Methodology section of this chapter.

Several pieces offered a comprehensive review of the historical literature on the formation of Black English as a construct in the context of slavery and Jim Crow, and the historical teaching of Black English within the U .S. context, including Wheeler ( 2016 ) and Alim and Baugh (2007). Wheeler (2016) equated Standard English with ‘White’ English and challenged its hegemony in dialectically diverse classrooms. She named the “racism inherent in [fostering] bidialectalism [th rough teaching]” (p. 380), arguing that we are acknowledging that the only way for African-Americans to be upwardly mobile was to learn how to speak ‘White’ English. Alim (2010) , explained, “By uncritically presenting language varieties as ‘equal’ but diff ering in levels of ‘appropriateness,’ language and Dialect Awareness programs run the risk of silently legitimizing ‘Standard English’” (p. 215)…. Current work addressing AAVE studies has been shifting focus to translingualism and to promoting such pedag ogies as code-meshing (Young, Barrett, Young Rivera and Lovejoy, 2014) and translanguaging (García & Wei, García and Wei, 2014) , embedded in a critical analysis of the racial logics underpinning the denigration of some languages. This work, combined with e xtensive examinations of the connections between race, language, teaching, and identity ( e.g. Flores & Rosa, 2015; Alim et al., 2016 ), has laid a foundation for a raciolinguistics approach to teaching, which we return to later in this article. (Von Esch et al., 2020, p. 399, emphasis added .)

In the first sentence, we see two narrative citations just before the period. These citations state the authors’ names as a part of the sentence, and put the publication date of the articles in parenthesis. It makes sense to use a narrative citation in the topic sentence, since most of the paragraph is a synthesis of Wheeler and Alim’s research. The second sentence starts with Wheeler’s name in the subject position, and the fourth sentence starts with Alim’s name in the subject position—both are narrative citations, a form chosen by the author to emphasize the importance and similarities in the two articles.

In the last two sentences, we see parenthetical citations. The citation information is in parenthesis within the sentences, which focuses the reader on the ideas, not the research itself. Imagine you were reading this article out loud—you would most certainly say the narrative citations “Wheeler” and “Alim”; you might choose not to say “Young, Barrett, Young-Rivera, & Lovejoy, 2014,” though, and no one listening to you would notice the omission. This is the most important difference between narrative and parenthetical citation—narrative draws attention to the researchers, while parenthetical allows a focus on ideas. In academic writing, you often have reason to use both, but it is important to note that using parenthetical citation is less disruptive to your voice—it keeps a reader focused on the ideas you are explaining.

Usually you are citing a type of quotation in your text (although different disciplines have other situations that they cite). Direct quotation and paraphrase are usually what we talk about when we talk about using resources in your writing, although summary is cited as well.

Direct quotation is when you take the original words of one author and place them in your own text. When you quote in your own writing, you mark the copied text—usually with quotation marks “” around the text and a citation afterwards. Quoting is useful when the original author is an important authority on a topic or if you want to define/describe another’s point of view in a way that leaves no room for misinterpretation.

In a literature review, a direct quote will almost always be accompanied by a narrative citation. But direct quoting can cause some issues in your own text, such as a sudden shift in voice and a loss of cohesion; the potential for misunderstanding and misrepresentation, since the quote has been separated from its original context; and wordiness —quotes can take up too much space both in terms of the quote itself, and of the explanation and context you must provide for the introduced idea. For these reasons, literature reviews do not contain much direct quoting.

Paraphrasing is a way to accomplish similar goals to direct quoting without causing the same problems. Paraphrasing is when you use only the original author’s key terms and ideas, but your own words. Paraphrasing still contains a citation afterwards that directs the reader to the full bibliographic information in your Works Cited, but does not require quotation marks since the language is yours. Paraphrase may be longer or shorter than the original author’s text, and uses both narrative and parenthetical citation. Paraphrase also allows you to cite more than one piece of research containing the same idea in a single sentence, such as the last sentence in the example paragraph above. This kind of citation string is important to literature reviews because it clearly identifies patterns and trends in research findings.

Key Takeaways

• Literature reviews are a synthesis of what other researchers have discovered on your topic. Think of reviews as “the big picture.”
• Taking so much information from other sources can get confusing–use section headings to keep your review organized and clear.
• Diverse citation, quotation, and paraphrasing techniques are necessary to help your reader understand where the ideas are coming from, AND to help make the ideas “stick together.”
• Keeping all the new knowledge you are learning from your sources organized is hard! Take notes using citations and use a graphic organizer to keep yourself on track.

Fernandez, Lord, H., Halcomb, E., Moxham, L., Middleton, R., Alananzeh, I., & Ellwood, L. (2020). Implications for COVID-19: A systematic review of nurses’ experiences of working in acute care hospital settings during a respiratory pandemic. International Journal of Nursing Studies , 111. https://doi.org/10.1016/j.ijnurstu.2020.103637

Kassin, S. M., & Gudjonsson, G. H. (2004). The psychology of confessions. Psychological Science in the Public Interest , 5 (2), 33–67. https://doi.org/10.1111/j.1529-1006.2004.00016.x

National Council of Teachers of English. (2018, June 16). Students’ right to their own language (with bibliography) . Conference on College Composition and Communication. Retrieved July 24, 2022, from https://cccc.ncte.org/cccc/resources/positions/srtolsummary

NEIU Libraries. (2020). “How should I search in a database?”  YouTube . https://www.youtube.com/watch?v=8fgBF0EuH_o

Ratcliffe, E. (2021). Summary Flowchart [Image]. Frontiers in Psychology. https://www.frontiersin.org/articles/10.3389/fpsyg.2021.570563/full#B3

Ratcliffe, E. (2021). Sound and soundscape in restorative natural environments: A narrative literature review. Frontiers in Psychology , 12 . https://doi.org/10.3389/fpsyg.2021.570563

Sasaki. K. (2022). Synthesis and Recipes [Image].

Von Esch, K., Motha, S., & Kubota, R. (2020). Race and language teaching. Language Teaching, 53 (4), 391-421. doi:10.1017/S0261444820000269

Writing for Inquiry and Research Copyright © 2023 by Charitianne Williams is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License , except where otherwise noted.

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• Research guides

Writing a Literature Review

Phase 1: scope of review, it's a literature review of what, precisely.

Need to Have a Precise Topic It is essential that one defines a research topic very carefully. For example, it should not be too far-reaching. The following is much too broad:

"Life and Times of Sigmund Freud"

However, this is more focused and specific and, accordingly, a more appropriate topic:

"An Analysis of the Relationship of Freud and Jung in the International Psychoanalytic Association, 1910-1914"

Limitations of Study In specifying precisely one's research topic, one is also specifying appropriate limitations on the research. Limiting, for example, by time, personnel, gender, age, location, nationality, etc. results in a more focused and meaningful topic.  

Scope of the Literature Review It is also important to determine the precise scope of the literature review. For example,

• What exactly will you cover in your review?
• How comprehensive will it be?
• How long? About how many citations will you use?
• How detailed? Will it be a review of ALL relevant material or will the scope be limited to more recent material, e.g., the last five years.
• Are you focusing on methodological approaches; on theoretical issues; on qualitative or quantitative research?
• Will you broaden your search to seek literature in related disciplines?
• Will you confine your reviewed material to English language only or will you include research in other languages too?

In evaluating studies, timeliness is more significant for some subjects than others. Scientists generally need more recent material. However, currency is often less of a factor for scholars in arts/humanities. Research published in 1920 about Plato's philosophy might be more relevant than recent studies.

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• Next: Phase 2: Finding Information >>
• Last Updated: Dec 5, 2023 2:26 PM
• Subjects: Education , General
• Tags: literature_review , literature_review_in_education

3.3 The Literature Review

[1] Another way to gather sources and present the information you have gathered utilizing primarily summaries is a literature review. This type of project is a survey of everything [2] that has been written about a particular topic, theory, or research question. The word “literature” means “sources of information.” The literature will inform you about the research that has already been conducted on your chosen subject. This is important because we do not want to repeat research that has already been done unless there is a good reason for doing so (i.e. there has been a new development in this area or testing a theory with a new population, or even just to see if the research can be reproduced).  Literature reviews usually serve as a background for a larger work (e.g. as part of a research proposal), or it may stand on its own. Much more than a list of sources, an effective literature review analyzes and synthesizes information about key themes or issues.

Purpose of a literature review

The literature review involves an extensive study of research publications, books, and other documents related to the defined problem. The study is important because it advises you, as a researcher, whether the problem you identified has already been solved by other researchers. It also advises you as to the status of the problem, techniques that have been used by other researchers to investigate the problem, and other related details.

A literature review goes beyond the search for information and includes the identification and articulation of relationships between existing literature in your field of research. The literature review enables the researcher to discover what has been already been written about a topic and to understand the relationship between the various contributions. This will enable the researcher to determine the contributions of each source (books, article, etc.) to the topic. Literature reviews also enable the researcher to identify and (if possible) resolve contradictions and determine research gaps and/or unanswered questions.

Even though the nature of the literature review may vary with different types of studies, the basic purposes remain constant.

• Provide a context for your research;
• Justify the research you are proposing;
• Show where your proposed research fits into the existing body of knowledge;
• Enable the researcher to learn from previous theory on the subject;
• Illustrate how the subject has been studied previously;
• Highlight flaws in previous research;
• Outline gaps in previous research;
• Show how your proposed research can add to the understanding and knowledge of the field;
• Help refine, refocus, or even move the topic in a new direction

What is involved in writing a literature review?

• Research – to discover what has been written about the topic;
• Critical Appraisal – to evaluate the literature, determine the relationship between the sources, and ascertain what has been done already and what still needs to be done;
• Writing – to explain what you have found

Generally speaking, it is helpful to think of the literature review as a funnel.  One starts with a broad examination of the research related to the issue, working down to look at more specific aspects of the issue, which leads to the gap or the specific issue that your research will address.

How to undertake a literature review

The first step in undertaking a literature review is to conduct a library search of academic research that has been done on your topic. This can be done electronically, or if you are within close vicinity to a library, you can go in and use their computers to find electronic and print holdings. You can also use Google Scholar for your search. In some cases, research conducted outside academia can serve as an important research source for your literature review. Indeed, such research can have important practical implications, as opposed to academic research which usually (although not always) tends toward theoretical applications.

However, it is important to understand who funded the research you review, in addition to the perspective and the purpose of the research. Review Chapter 2 “Warming Up: The Ins and Outs of Sources” to recap how to vet sources and where to find them.

As part of this first step, there are a few more things to be thinking about as you review the literature

• Who are the various researchers who have studied this topic?  Who are the most prolific researchers/writers on this topic? Has a specific researcher or teams of researchers been identified as pioneers or leaders in this field of study?
• How have the various researchers defined key terms that are relevant to your topic? Have the definitions of any of the key terms evolved over time?
• What are the different theories that have been examined and applied to this topic? How, if at all, have the various theories applied to this topic over time evolved?
• What methodologies have been used to study this topic?  Have the methodologies evolved over time?

In addition to thinking about these questions, you should be taking notes during this process. If you are finding your sources online and viewing them as PDFs via a database, you can download the file and annotate as you read using software like Adobe Reader and Kami. Annotating, according to Webster , is “a note added by way of comment or explanation.” Simply put, it means actively reading and taking notes during the process of your research. For a lot of people, this boils down to highlighting/underlining passages, charts, graphs, and data that they interpret as important to the overall article’s purpose. This also includes drafting comments in the margins that explain the thought process you had when you decided that the information you marked was important. Annotating may feel time-consuming and, to some, like “busy work,” but if you trust the process, when you go to put together the project using those sources, it will be much easier as you will have your own thoughts to review in order to track back why you kept a source and why you wanted to use it as evidence in your research project.

Your notes for a source should include marking (either by highlighting or drafting a note) information similar to the following.

• If the article is empirical, write down the results of the research study in one or two sentences of your own words. e.g. “people who are between ages 18 – 35 are more likely to own a smart phone than those above or below.”  It is also a good idea to make note of the methods, the research design, the number of participants and details on the sample used in the study. Sometimes, you may even want to write down the names of the statistical procedures used to analyze the data or even some of the statistics, depending on your assignment.
• If the article is a review of previous research, look for the main points. It may be helpful to read or skim the whole article, look away, and ask yourself what you felt was the main idea.
• Write down any limitations or gaps you notice, anything that seems to contradict something you read elsewhere, or just anything that you think is important or interesting [3]

When reading through your sources, remember that you are looking for the “big picture,” not a collection of separate articles all tangentially about the same topic (an annotated bibliography). You are also not trying to prove a point (an essay). You are looking for common themes and patterns in the research as a whole. You are also looking to see how the various pieces of research are linked, if at all. As part of this process, you also want to identify research gaps or areas that require further research related to your topic [4] . In this regard, you cannot be expected to be an expert on your topic. A suggestion for finding gaps is to read the conclusion section of the academic journal articles and conference proceedings your search has uncovered. Researchers often identify gaps in the research in their conclusion. They may even suggest areas for future research. However, remember, if a researcher suggested a gap 10 years ago, it is likely that the gap has now been addressed. To find a gap, look at the most recent research your literature review has uncovered (within 2-3 years of the current date). At this point in your search of the literature, you may realize that your research question needs to change or adapt. This is a fairly common occurrence, as when you first develop a research question, you cannot be sure what the status of the research area is until you undertake your review of the literature related to this topic. Finally, it is worth mentioning that it is very likely you will not include all of the resources you have read in your literature review. If you are asked to include 20 resources in your literature review, for example, expect to read approximately 30.

How to write a literature review

There are three parts to the literature review: the introduction, the body, and the conclusion.

Introduction

• The introduction must identify the topic by briefly discussing the significance of the topic including a statement that outlines the conclusion to be drawn from the literature review.
• If your literature review is part of a larger work, explain the importance of the review to your research question.
• Defend the importance of the topic by giving a broad overview of the scope of the work you are reviewing. For example, if you are interested in post-traumatic stress disorder (PTSD) in paramedics, you might provide some stats to prove how much work time is lost by those suffering from PTSD.
• Clarify whether you are looking at the entire history of the field or just a particular period of time.
• Discuss and assess the research according to specific organizational principles (see examples below), rather than addressing each source separately. Paragraphs should discuss more than one source. Avoid addressing your sources alphabetically as this does not assist in developing the themes or key issues central to your review.
• Compare, contrast, and connect the various pieces of research. Much of the research you are reading should be connected. You may notice various themes within the research (i.e. effects of PTSD on sick time, effects of PTSD on families of paramedics, effects of PTSD on overall paramedic wellness, etc.). If you have undertaken a thorough review of the literature, you should start to see the bigger picture of how the research on this topic has evolved over time, who the main researchers are on this topic, and how the methods and theories related to this topic have changed (if at all).
• Summarize the works you are reviewing. Just as in any written assignment, use logical organization and clear transitions.

Based on your research, suggest where the research in the field will or should go next. If you are proposing your own research study, show how you will contribute to the field and fill in any gaps. The conclusion would also be a good place to defend the importance of the topic, now that you have demonstrated the current state of thinking in the field. You may also want to consider noting any gaps in your own research. Were their groups, questions, data, etc. that you did not look at in your research? If so, why?

Organization and source types in literature reviews

Table 3.3.1 provides some suggested organizational techniques, as well as instances when you might use these various techniques.  The table also provides a writing sample to demonstrate the writing technique.

Acceptable sources for literature reviews

There are sources that are considered more acceptable for literature reviews. Below they are listed in order from what is considered most acceptable to less acceptable sources for literature review assignments.

• Peer reviewed journal articles;
• Edited academic books;
• Articles in professional journals;
• Website material from professional associations (use sparingly and carefully);

Peer reviewed journal articles (papers)

A peer reviewed journal article is a paper that has been submitted to a scholarly journal, accepted, and published. Peer review journal papers go through a rigorous, blind review process of peer review. What this means is that two to three experts in the area of research featured in the paper have reviewed and accepted the paper for publication. The names of the author(s) who are seeking to publish the research have been removed (blind review), so as to minimize any bias towards the authors of the research. Albeit, sometimes a savvy reviewer can discern who has done the research based upon previous publications, etc. This blind review process can be long (often 12 to 18 months) and may involve many edits on the behalf of the researchers, as they work to address the edits and concerns of the peers who reviewed their paper. Often, reviewers will reject the paper for a variety of reasons, such as unclear or questionable methods, lack of contribution to the field, etc. Because peer reviewed journal articles have gone through a rigorous process of review, they are considered to be the premier source for research. Peer reviewed journal articles should serve as the foundation for your literature review.

Edited academic books

The papers within the text also go through a process of review; however, the review is often not a blind review because the authors have been invited to contribute to the book. Consequently, edited academic books are fine to use for your literature review, but you also want to ensure that your literature review contains mostly peer reviewed journal papers.

Articles in professional journals

Articles from professional journals should be used with caution, as far as it relates to a source for your literature review. This is because articles in trade journals are not usually peer reviewed, even though they may appear as such. A good way to find out is to read the “About us” section of the professional journal. They should state there if the papers are peer reviewed. You can also google the name of the journal and add peer reviewed to the search and you should be able to find out that way.

Website material from professional associations

Material from other websites can also serve as a source for statistics that you may need for your literature review.  As you want to justify the value of the research you are interested in, you might make use of a professional association´s website to learn how many members they have, for example.  As a hypothetical example, you might want to demonstrate, as part of the introduction to your literature review, why more research on the topic of PTSD in police officers is important.  You could use peer reviewed journal articles to determine the prevalence of PTSD in police officers in Canada in the last ten years and then use the Ontario Police Officers´ Association website to determine the approximate number of police officers employed in the Province of Ontario over the last ten years. This might help you create an approximation of how many police officers could be suffering with PTSD in Ontario.  That number could potentially help to justify a research grand down the road. But again, this type of website-based material should be used with caution and sparingly. [6]

The Five ‘C’s of Writing a Literature Review [7]

To help you frame and write your literature review, think about these five ‘c’s.

• Cite the material you have referred to and used to help you define the research problem that you will study.
• Compare the various arguments, theories, methods, and findings expressed in the literature.  For example, describe where the various researchers agree and where they disagree. Describe the similarities and dissimilarities in approaches to studying related research problems.
• Contrast the various arguments, themes, methods, approaches, and controversies apparent and/or described in the literature.  For example, describe what major areas are contested, controversial and/or still in debate.
• Critique the literature.  Describe which arguments you find more persuasive and explain why.  Explain which approaches, findings, and methods seem most reliable, valid, appropriate, and/or most popular and why.  Pay attention to the verbs you use to describe what previous researchers have stated (e.g. asserts, demonstrates, argues, clarifies, etc.).
• Connect the various research studies you reviewed.  Describe how your work utilizes, draws upon, departs from, synthesizes, adds to or extends previous research studies.

Difference between a literature review and an essay

So now that you know what a literature review is and how to write it, it is important to understand how a literature review is different from an essay. First of all, it is necessary to point out that many students struggle with understanding the difference between a literature review and an essay. This is particularly so because the exact same resources used to create a literature review can be used to create an essay; however, what is different about the two is where the emphasis in the writing is placed. [8]

As discussed previously, a literature review focuses on everything that has been written about a particular topic, theory, or research. It is focused on the research and the researchers who have undertaken research on your topic. In contrast, an essay focuses on proving a point. It does not need to provide an extensive coverage of all of the material on the topic. In fact, the writer chooses only those sources that prove the point. Most professors will expect to see you discuss a few different perspectives from the materials that run contrary to the point you are trying to make. For example, suppose you want to write an essay about the negative effects of shiftwork on nurses. You would gather material to show that shiftwork negatively affects nurses, and the various ways it affects nurses. Now, in this case, you might find the odd research paper that states shiftwork has no effect – although, I doubt it, because it has been extensively documented to have a negative effect. However, the point is that with an essay you are focused on providing information on your topic and proving your point which means that your argument should not be in a literature review as that type of paper is not about what you believe or want to argue should be considered; it is about the current conversation you are planning to enter.

Difference between a literature review and an annotated bibliography

Another type of academic writing that can also confuse students who are attempting to write a literature review is one that you have already learned about in this chapter–the annotated bibliography.

However, the main difference between an annotated bibliography and a literature review falls on the level of synthesis that happens among the sources. In an annotated bibliography (like we discussed earlier in this chapter), you are creating stand-alone summaries about each source in your paper. These sources should be related in the sense that they are all about the same general research topic; however, in this type of paper, you do not have to look for connections beyond making sure they are discussing the same topic. In a literature review, you have to link the sources to one another (which means your summaries are typically much shorter in a literature review than they are in an annotated bibliography). You move from writing one summary about each source in a single paragraph to connecting several condensed summaries about 2 or more sources in one paragraph. A literature review focuses more on creating a big picture between the sources by grouping like sources together and using transition phrases/words to develop a link between said sources or synthesizing.

[9] Synthesis as  Conversation Among the Authors of Your Source Materials

To synthesize is to combine ideas and create a completely new idea. That new idea becomes the conclusion you have drawn from your reading. This is the true beauty of reading: it causes us to weigh ideas, to compare, judge, think, and explore—and then to arrive at a moment that we hadn’t known before. We begin with summary , work through analysis , evaluate using critique , and then move on to synthesis .

How do you synthesize?

Synthesis is a common skill we practice all the time when we converse with others on topics we have different levels of knowledge and feelings about. When you argue with your friends or classmates about a controversial topic like abortion or affirmative action or gun control, your overall understanding of the topic grows as you incorporate their ideas, experiences, and points of view into a broader appreciation of the complexities involved. In professional and academic writing, synthesizing requires you to seek out this kind of multi-leveled understanding through reading, research, and discussion. Though, in academic writing, this is another kind of discussion: you set the goal for the discussion, organize the discussion among the authors of your found researched materials, orchestrate the progress of the discussion, build logical guidance for your audience, and finally you draw your conclusion on the topic.

Below are some steps you can use to help you synthesize research:

• Determine the goal(s) for your discussion such as reviewing a topic or supporting an argument
• Organize the discussion among the authors of your found researched materials
• Lead the discussion among the authors of your sources
• Summarize the most vivid of the authors’ examples and explanations
• Finally, draw your unique conclusion on the topic: in fact, the answer to your research question

What synthesis is NOT

Synthesizing does not mean summarizing everyone’s opinion: “Julia is pro-life, and Devon is pro-choice, and Jasmine says she thinks women should be able to have abortions if their life is in danger or they’ve been the victims of rape or incest.”

Synthesizing does not mean critiquing opinions: “Rick tried to defend affirmative action, but everyone knows it’s really reverse racism.”

Synthesizing does not simply compare texts (unless assigned as such by your instructor). You are neither evaluating nor comparing the effectiveness of the authors’ presentations.

What synthesis IS

Instead, synthesis demonstrates YOUR full, objective , empathetic understanding of a topic from multiple perspectives. When you synthesize, you “cook” the ideas and opinions of others by thinking, talking, and writing about them, and what comes out is a dish full of many blended flavors but uniquely your recipe:

Notice that this synthesis does not crouch behind limited and thoughtless positions: “You can’t change the Second Amendment!” “Ban all guns!” This synthesis instead tries to depict the hard reality: guns are an integral part of American culture, and so is gun violence, and limiting the latter can not be done without impacting the former. This synthesis reserves judgment and aims for understanding. In order to gain an unbiased and fair understanding of a topic, you must read research from all sides of the conversation (even if you think you disagree with that side before you begin researching).

• 3.3 (excepts where otherwise noted) was borrowed with minor edits and additions from An Introduction to Research Methods in Sociology  by Valerie A. Sheppard which is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License ↵
• relatively speaking. It is a daunting task to read EVERYTHING that has ever been written on a topic (especially in a semester); however, literature reviews are composed of multiple sources covering a specific topic--much like an annotated bibliography. ↵
• Adjei, J. K. (n.d.).  Research methods . Retrieved from African Virtual University website:   https://oer.avu.org/handle/123456789/490 ↵
• Ibid. ↵
• Editage Insights . (2021, March 3). Q: W hich is considered the highest academic publication among a book, an edited book, and a book chapter? https://www.editage.com/insights/which-is-considered-the-highest-academic-publication-among-a-book-an-edited-book-and-a-book-chapter ↵
• Derived from Callahan, J. L. (2014). Writing literature reviews: A reprise and update. Human Resource Development Review, 13(3), 271 –275. https://doi.org/10.1177/1534484314536705 ↵
• Thomas, J. (2012, September 26).  Literature review vs. essay [Blog post].  Retrieved from  https://blogs.qut.edu.au/library/2012/09/26/literature-review-vs-essay/ ↵
• Borrowed with minor edits and additions from "5.2 Synthesizing in Your Writing" by Yvonne Bruce, Melanie Gagich, and Svetlana Zhuravlova which is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License ↵

Composition 2: Research and Writing Copyright © by Brittany Seay is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Academic Composition

How to write a literature review.

• April 3, 2024
• , Uncategorized

In the academic realm, literature reviews serve as the backbone of scholarly research, providing a comprehensive analysis of existing literature on a particular topic. Whether you’re a seasoned scholar or a budding academic, understanding how to craft a compelling literature review is essential for navigating the intricate world of academia. In this guide, we’ll delve into the intricacies of writing a literature review, offering concrete steps to help you master this critical aspect of academic writing.Understanding the Literature Review. Before delving into the nitty-gritty of writing a literature review, it’s crucial to grasp its essence. A literature review is not simply a summary of existing literature; rather, it’s an analytical synthesis that critically evaluates, interprets, and synthesizes relevant sources to provide a comprehensive understanding of a particular research topic or question.

A well-crafted literature review accomplishes several key objectives:

Contextualization: It situates your research within the broader scholarly conversation, highlighting gaps, trends, and debates in the literature.Critical Analysis: It evaluates the strengths and weaknesses of existing studies, identifying methodological flaws, biases, and areas for further investigation.

Synthesis: It synthesizes diverse sources to construct a coherent narrative, elucidating key themes, theories, and findings relevant to your research.Identification of Research Gaps: It identifies areas where further research is needed, paving the way for new avenues of inquiry.

Writing a Literature Review: Step-by-Step GuideChoose a Topic: Select a narrow, focused topic that aligns with your research interests and academic goals. Consider the scope and relevance of existing literature to ensure a fruitful exploration. Conduct Comprehensive Research: Utilize academic databases, scholarly journals, books, and other credible sources to gather relevant literature. Pay attention to recent publications and seminal works in your field.

Organize Your Sources: Create a systematic approach to organizing your sources, categorizing them based on themes, theories, methodologies, or chronological order. This will streamline the writing process and help you identify patterns and connections among different sources.

Critical Analysis: Evaluate each source critically, considering its credibility, methodology, theoretical framework, and relevance to your research question. Identify key arguments, findings, and limitations of each study.

Synthesize Information: Synthesize the information gleaned from your sources, identifying common themes, trends, and controversies in the literature. Highlight overarching theories and concepts that underpin the research in your field.

Develop a Structure: Structure your literature review in a coherent and logical manner, organizing it into sections such as introduction, thematic analysis, critical evaluation, and conclusion. Ensure smooth transitions between paragraphs and sections.

Write Clearly and Concisely: Write in a clear, concise, and scholarly manner, avoiding jargon and ambiguous language. Use proper citation and referencing style according to the guidelines of your academic institution.

Revise and Edit: Review your literature review thoroughly, paying attention to clarity, coherence, and logical flow. Edit for grammar, punctuation, and spelling errors to ensure a polished final draft.How Academic Composition Can Help You ExcelNavigating the intricacies of writing a literature review can be daunting, especially for students juggling multiple academic responsibilities.

That’s where Academic Composition comes in. As a premier provider of academic writing services, we offer comprehensive assistance to help students excel in their academic endeavors.Our team of experienced writers specializes in crafting high-quality literature reviews tailored to your specific requirements. Whether you need assistance with topic selection, literature search, critical analysis, or writing and editing, our experts are here to guide you every step of the way.

By entrusting your literature review to Academic Composition, you can:Save Time and Effort: Focus on other academic tasks while our experts handle the intricacies of literature review writing. Ensure Quality and Originality: Receive a well-researched, meticulously written literature review that adheres to the highest academic standards.Gain Valuable Insights: Benefit from the expertise of our writers, who bring years of experience and subject matter expertise to every project.

Meet Tight Deadlines: Whether you’re facing a tight deadline or struggling to balance academic and personal commitments, we deliver prompt and reliable service to meet your needs.In conclusion, mastering the art of writing a literature review is a fundamental skill for university students seeking to excel in their academic pursuits. By following the steps outlined in this guide and leveraging the expertise of Academic Composition, you can navigate the complexities of literature review writing with confidence and precision, paving the way for academic success and career advancement.

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Our team of professional writers offers expertise in a wide variety of topics for various academic disciplines, ranging from history and philosophy to natural science and engineering. Our writers were all educated in the United States and hold advanced degrees in their field(s) of specialization.

AP® English Literature

The best ap® english literature review guide for 2024.

• The Albert Team
• Last Updated On: January 29, 2024

Scoring a 5 on the AP® English Literature and Composition exam is no easy task. In 2019, for example, only 6.2% of students earned a 5 on the test. While this statistic may be discouraging at first glance, it does indicate that a perfect score is possible for those willing to do extra preparation and practice. In 2022, nearly 17% of test-takers earned a 5 – a big improvement!

It may take some hard work, but it’s possible to ace this exam! We’re here to help.

In this comprehensive review, we’ll unpack the exam’s basic format, analyze the common structures and shapes of AP® Literature questions, provide useful tips and strategies for scoring a 5, and offer a variety of helpful additional resources and study tools.

Let’s get to it!

What We Review

How is the AP® English Literature and Composition Exam formatted? 

The AP® English Literature and Composition exam is divided into two sections: multiple-choice and free-response. 

The multiple-choice section is broken into five chunks equipped with 8-13 questions each, totaling 55 questions. You will be asked to analyze excerpts from diverse literary texts, including prose fiction, drama, or poetry. Moreover, there will always be at least 2 prose fiction passages and 2 poems in this section of the exam. The fifth text can be either. 

The multiple-choice section has a time limit of 1 hour, and it counts as 45% of your overall exam score. 

Section 2 of the exam, often informally called the “essay section,” contains 3 free-response prompts which demand literary analysis of a given poem, a passage of prose fiction, or an excerpt from a play. 

The first two prompts will provide a passage or a poem requiring analysis, while the third and final prompt will ask you to engage with a concept, issue, or element in a literary work that you are expected to have encountered during the school year. A list of appropriate works is provided for the third prompt. 

You have 2 hours to complete Section 2, which comprises 55% of your final exam score.

Return to the Table of Contents

How Long is the AP® English Literature and Composition Exam?

The AP® English Literature and Composition exam is 3 hours long. Students will have 1 hour to complete the multiple-choice section (55 questions) and 2 hours to complete the free-response section (3 questions). 

Since you must answer 55 questions in 60 minutes on the multiple-choice portion of the exam, you should pace yourself at about 1 minute per question and about 12 minutes per passage. 

Likewise, since the free response section is timed at 120 minutes, you should aim to complete each essay in 40 minutes or under.

Time yourself when you practice, and don’t get caught up trying to answer a question that you totally do not know the answer to. Don’t rush through the test, but don’t take too much time.

How Many Questions Does the AP® English Literature and Composition Exam Have? 

Section i: multiple-choice.

• 5 passages, 55 questions total: 8-13 questions per passage
• Passages include 2 Prose, 2 Poems, and 1 of either

Section II: Free-Response

• 1 literary analysis of a given poem
• 1 literary analysis of a given passage of prose fiction
• 1 literary argument

What Topics are Covered on the AP® English Literature and Composition Exam? 

Perhaps the best way to begin thinking about the topics covered on the exam is through a holistic approach. Overall, the test assesses the six big ideas covered within the AP® English Literature and Composition course itself: 

• Figurative Language
• Literary Argumentation

These components comprise the whole exam, and you will be tested specifically on material from these broad concepts. 

Now, let’s return to its formatting. Remember, the exam is divided into multiple choice and free response, each carrying its own set of demands and topics.

Section I: Multiple Choice

Since the AP® English Literature and Composition exam is a skills-based test, there’s no way to know what specific passages or topics might appear on the official exam. Rather, CollegeBoard uses a variety of excerpts from literary texts, including prose, poetry, and drama. 

The passages often range from the 16th to the 21st century, and the authors and literary works change yearly. So it is imperative that you sharpen your critical reading skills and hone your ability to engage with the forms, styles, and content of a diverse range of literature. 

However, we have some good news. We do know how the multiple choice section is organized and weighted. It is divided into three broad units: short fiction, poetry, and longer fiction or drama, with each unit carrying its own weighted percentage. The chart below outlines this weighting:

Moreover, the multiple choice portion of the exam can be further broken down into 7 assessed skills:

Remember, the multiple-choice section will include five sets of 8 to 13 questions per set, so be prepared to encounter many if not all of these skill sets per passage. But it is safe to say that you should review certain skill categories more thoroughly than others on account of how frequently they appear on the exam. 

Below we’ve compiled a descending list of priorities for you to consider. 

• Skill Category 4 : Explain the function of the narrator or speaker
• Skill Category 1 : Explain the function of character
• Skill Category 3 : Explain the function of plot and structure
• Skill Category 5 : Explain the function of word choice, imagery, and symbols
• Skill Category 7 : Develop textually substantiated arguments about interpretations of part or all of a text
• Skill Category 6 : Explain the function of comparison
• Skill Category 2 . Explain the function of setting

Section 4, “Explain the function of the narrator or speaker,” should be studied the most since it holds a substantial amount of weight in determining your score. Skill category 2, as you see above, accounts for a small percentage of the exam so we recommend you don’t spend hours upon hours brushing up on the function of the setting. Don’t blow it off, though!

Section II: Free Response

Like the multiple choice section, the free response portion is also skills-based. We cannot predict what specific passages or poems will make it onto the test, but we do know the type(s) of essays you will be required to write:

• 1 Poetry Analysis: After reading a poem of 100 to 300 words, you will respond to a prompt based on the poem with a well-developed essay. Your essay, of course, must offer a defensible interpretation, make adequate use of textual evidence, engage critically with cited evidence, and use appropriate grammar and punctuation when communicating its argument. These requirements are present throughout all three free-response essays. 
• 1 Prose Fiction Analysis: This part of the free response section will provide a passage of prose fiction (500 to 700 words) and, like the poetry analysis, ask you to respond to a prompt through writing a well-developed essay. Your argument must adhere to the rigor and clarity outlined above in the poetry analysis description.
• 1 Literary Argument Essay: Here, you will be given an open-ended topic and be asked to write an evidence-based argumentative essay in response to the topic. There will be a quote or small passage to read, a corresponding prompt, and an extensive list of literary works you may use when developing your argument. While you do not have to use a work from this list, you must select a work of literary merit. Avoid choosing fantasy novels or works designed more for pure entertainment. It needs to be a work of “deep” literature.

What Do the AP® English Literature and Composition Exam Questions Look Like?

Multiple choice examples:.

The Course and Exam Description (CED) for AP® Lit provides 10 practice questions that address prose fiction and 9 practice questions that address poetry.

Below, we’ll look at examples of each question type and cover the skills and essential knowledge they address. First, we will examine the multiple-choice questions involving prose fiction:

Skill: 5.B Explain the function of specific words and phrases in a text.

Essential Knowledge: FIG-1.M Descriptive words, such as adjectives and adverbs, qualify or modify the things they describe and affect readers’ interaction with the text.

Skill: 4.C Identify and describe details, diction, or syntax in a text that reveal a narrator’s or speaker’s perspective.

Essential Knowledge: NAR-1.R Information included and/or not included in a text conveys the perspective of characters, narrators, and/or speakers.

Skill: 3.C Explain the function of structure in a text.

Essential Knowledge: STR-1.F A text’s structure affects readers’ reactions and expectations by presenting the relationships among the ideas of the text via their relative positions and their placement within the text as a whole

Now that we’ve taken a look at samples of multiple-choice questions involving prose fiction, let’s turn our attention toward questions that address poetry. 

Skill 7.B: Develop a thesis statement that conveys a defensible claim about an interpretation of literature and that may establish a line of reasoning. 

Essential Knowledge: LAN-1.D A thesis statement expresses an interpretation of a literary text, and requires a defense, through use of textual evidence and a line of reasoning, both of which are explained in an essay through commentary.

Skill 4.C: Identify and describe details, diction, or syntax in a text that reveal a narrator’s or speaker’s perspective.

Essential Knowledge: NAR-1.X Multiple, and even contrasting, perspectives can occur within a single text and contribute to the complexity of the text.

Skill: 5.D Identify and explain the function of an image or imagery.

Essential Knowledge: FIG-1.O Descriptive words, such as adjectives and adverbs, contribute to sensory imagery.

As you see, these questions force you to engage with literature more critically and technically. CollegeBoard’s main objective is to shape you into a budding literary critic capable of producing college-level work, so they consistently ask questions that look like those above. 

To develop your skills to a level that would be acceptable by a university, then, the test-makers over at CollegeBoard often craft questions involving analysis of literary devices, character perspective, figurative language, and more. The individual skills assessed by these questions are designed to take your thinking to a much higher level.

Free Response Examples: 

The Course and Exam Description (CED) for AP® Lit also provides samples of free response questions. Let’s begin by taking a look at a sample of a poetry-based free response prompt.

Poetry Analysis

Skills: 4.C, 7.A, 7.B, 7.C, 7.D, 7.E

Note how the prompt is somewhat vague and open-ended. While it does ask you to hone in on a specific topic within the poem—aging—through discussion of the writer’s use of poetic elements and techniques, it also does not specify which of those elements and techniques should be discussed:

• Then, in a well-written essay, analyze how Emerson uses poetic elements and techniques to convey the speaker’s complex perspective on aging.

So, it is imperative that you come to this exam with a deep and clear understanding of literary devices and motifs such as parallelism, imagery, irony, etc.

If you struggle with literary and rhetorical terms, check out our guide on essential AP® Literature Rhetorical Terms !

In a bit, we’ll provide some additional resources to help you build your knowledge of these literary tools.

Prose Fiction Analysis

Skills: 1.A, 7.A, 7.B, 7.C, 7.D, 7.E

The prompt requires you to read the excerpt and construct a well-developed literary analysis in response. Like the poetry prompt, note how this prompt is somewhat vague and open-ended. Again, it points you in a direction but leaves it up to you on how you’re going to get there:

• Then, in a well-written essay, analyze how Kincaid uses literary elements and techniques  to portray the complexity of the narrator’s new situation.

Therefore, it is imperative that you come to the test prepared with knowledge of literary elements and techniques.

Literary Argument 

Skills: 1.E, 2.C, 7.A, 7.B, 7.C, 7.D, 7.E

Unlike the other two essays, this prompt contains neither a prose excerpt nor a poem. Rather, it provides a brief quote and then asks you to expand on its central concept and, in our case, the notion of home. 

It then provides a list of works that would suit your analysis. You are to select one work from the list or choose another work of literary merit and analyze it in the context of the prompt. Again, note how much of the analysis is up to you. The prompt points you in a direction and then leaves you on your own to select how you’re going to get there. 

Therefore, it is imperative that you have not only a solid understanding of literary terms and concepts but also a diverse and deep history of reading. We will direct you toward some additional resources that will strengthen your knowledge below but start by consulting our Ultimate AP® English Literature Reading List to get started!

And if you’re not an avid reader, do not fret! You can guarantee the AP® English Literature and Composition course itself will cover at least one of the books on the list. You will likely be familiar with at least 2-3 of the texts just from taking the course. And if all else fails, you may select your own work of literary merit to discuss!

Free Response Rubric Breakdowns

In previous years, the AP® Lit essays were scored using holistic rubrics on a scale of 0-9. However, after the 2019 exam, the evaluation changed to a new analytic rubric which runs on a scale of 0-6. 

Switching to an analytic rubric from a holistic one can be difficult, especially if you’ve already taken another AP® English class or prepared using the holistic version. But, unlike the holistic rubric, the analytic model tells you exactly what to include in your essay to earn maximum points. 

Consider the new analytic rubric a How-To Guide, designed to earn you a 6 on each essay. And, unlike the AP® Lang exam, all three AP® Lit essays are graded essentially through the same rubric.

Below, we’ll spend some time breaking down the elements of the new rubric. First, let’s take a look at the Thesis row.

Row A: Thesis (0-1 Points)

A well-developed thesis statement is crucial to making your overall argument effective and convincing. Unsurprisingly, the Thesis row on the rubric is essentially all or nothing; you either earn the point or you don’t.

Let’s break down the wording on the rubric to further understand the significance of the thesis point.

It’s important to note what the rubric warns against: 

• No thesis at all
• The thesis only restates the prompt
• The thesis merely summarizes 
• The thesis does not respond to the prompt 

Doing any of these will miss the mark, and a weak thesis often leads to a weak essay. Rather, the rubric emphasizes that you: 

• Respond to the prompt with a thesis that presents a defensible interpretation of the poem, prose passage, or selected work.

Easier said than done, we know. But notice the key phrase, “defensible interpretation.” The basis of your argument, the rubric insists, is entirely up to you as long as you adequately defend and your point. This means you must be ready to dig into the text, cite textual evidence, and analyze your findings sophisticatedly and persuasively. Your thesis, then, must contain a claim. 

If thesis statements are particularly troubling to you, we recommend tuning into CollegeBoard’s official online workshop . It’s helpful, really. 

Below are two examples of thesis statements from the 2019 exam:

• This thesis statement thoroughly considers both the positive and negative consequences of idealism and explains how this portrayal illuminates the meaning of the work as a whole.
• This thesis statement fails to identify a character and confusingly identifies the government’s repressive efforts as presenting a “fabricated view of an Ideal world.” It ultimately makes no claim and overly generalizes.

Row B: Evidence and Commentary (0-4 Points)

Think of evidence and commentary as the meat of your essay. This is where you will really dig into your argument, cite the text, and make specific claims and arguments.

As mentioned, this portion of the rubric works on a scale of 0-4:

As you see, earning all four points requires direct and specific textual citation and thorough, deep analysis throughout your entire essay. Cite evidence that fits your main argument, do not simply cite for the sake of citation. Always avoid paraphrasing (except on the third free-response question where paraphrasing is acceptable). Do not simply cite text and then give a basic summary. Dig deep and analyze. 

If you struggle with analyzing evidence and developing commentary, check out one of our many practice models ! 

Row C Sophistication (0-1 Points)

Similar to the Thesis row, the Sophistication evaluation is also all or nothing — you either earn the point or you don’t. 

However, earning the sophistication point is not as cut and dry as earning the thesis point. You can’t really pinpoint or locate sophistication in the way you can a thesis statement. If it’s there, it’s everywhere; if not, it’s nowhere. 

So to unpack this complex idea, let’s return to the rubric. 

The rubric states that essays that earn the point “demonstrate sophistication of thought and/or develop a complex literary argument.” 

To be more precise, this means that your essay does these four things: 

• Identifies and explores complexities or tensions within the poem, prose passage, or selected work. 
• Situates your overall interpretation within a broader, more universal context. 
• Accounts for alternative interpretations of the poem, prose passage, or selected work. 
• Employs a style that is consistently vivid and persuasive.

Conversely, then, you will not earn the point if your essay:

• Contains sweeping generalizations
• Only hints at other positions or interpretations
• Uses overly complex sentences or language that doesn’t add anything to the argument

Above all, sophistication cannot be reduced to a checkbox. You can’t really add it here or there. It must pervade the entire essay for you to earn the point. It’s a difficult task, but it can be done with a little practice and perseverance. 

For additional tips on writing well-developed analyses, check out our guide on how to tackle prose passages !

What Can You Bring to the AP® English Literature and Composition Exam?

If you’re taking the  digital  exam, you must use a laptop computer (Mac, Windows, or school-managed Chromebook). Because the full-length digital AP® Exams require typewritten free responses, the exams can’t be taken on smartphones. For more details,  here is the full digital AP® exam specifications  from College Board.

If you’re traveling to a testing location to take an in-person exam, make sure to arrive early. If you’re testing digitally from home, be sure all of your digital login details are confirmed beforehand.

Given the sheer importance and seriousness surrounding AP® exams, the College Board has imposed very strict rules and regulations regarding what you can and cannot bring into your testing room (if you’re testing in-person at a school). Not adhering to these rules can lead to score invalidation and even room-wide exam cancellation, so it’s important to know what you can and cannot bring with you on testing day!

What You Should Bring to Your AP® English Literature Exam

If you’re taking the paper AP® English Literature exam in-person at school, you should bring:

• At least 2 sharpened No. 2 pencils for completing the multiple choice section
• At least 2 pens with black or blue ink only. These are used to complete certain areas of your exam booklet covers and to write your free-response questions. CollegeBoard is very clear that pens should be black or blue ink only, so do not show up with your favorite neon gel pen!
• You are allowed to wear a watch as long as it does not have internet access, does not beep or make any other noise, and does not have an alarm. It should be a standard analog or digital watch, nothing fancy!
• If you do not attend the school where you are taking an exam, you must bring a government issued or school issued photo ID.
• If you receive any testing accommodations , be sure that you bring your College Board SSD Accommodations Letter.

What You Should NOT Bring to Your AP® English Literature Exam

If you’re taking the paper AP® English Literature exam in-person at school, you should NOT bring:

• Electronic devices. Phones, smartwatches, tablets, and/or any other electronic devices are expressly prohibited both in the exam room and break areas. Seriously, do not bring these into the testing room. You could invalidate the entire room’s scores.
• Books, dictionaries, highlighters, or notes 
• Mechanical pencils, colored pencils, or pens that do not have black/blue ink. Sometimes the lead used in mechanical pencils cannot be read when run through the scantron reader, so it is best to just avoid them altogether. 
• Your own scratch paper
• Reference guides
• Watches that beep or have alarms
• Food or drink

This list is not exhaustive. Be sure to double-check with your teacher or testing site to make sure that you are not bringing any additional prohibited items.

How to Study for AP® English Literature and Composition: 7 Steps

Start with a diagnostic test to see where you stand. Ask your teacher if they can assign you one of our full-length practice tests as a starting point. Your multiple choice will be graded for you, and you can self-score your free response essays using the College Board’s scoring guidelines. If you would prefer to take a pencil and paper test, Princeton Review or Barron’s are two reputable places to start. Be sure to record your score.

Once you’ve completed and scored your diagnostic test, it’s time to analyze the results and create a study plan. 

• If you used Albert, you’ll notice that each question is labeled with the skill that it assesses. If any skills stand out as something you’re consistently getting wrong, those concepts should be a big part of your study plan. 
• If you used Princeton Review, Barron’s, or another paper test, do your best to sort your incorrect answers into the skill buckets from Albert’s AP® English Literature and Composition Standards Practice .

The tables below sort each set of skills into groups based on their Enduring Understandings and Big Ideas.

Big Idea: Character 

ENDURING UNDERSTANDING: Characters in literature allow readers to study and explore a range of values, beliefs, assumptions, biases, and cultural norms represented by those characters.

Big Idea: Setting

ENDURING UNDERSTANDING: Setting and the details associated with it not only depict a time and place, but also convey values associated with that setting.

Big Idea: Structure

ENDURING UNDERSTANDING: The arrangement of the parts and sections of a text, the relationship of the parts to each other, and the sequence in which the text reveals information are all structural choices made by a writer that contribute to the reader’s interpretation of a text.

Big Idea: Narration

ENDURING UNDERSTANDING: A narrator’s or speaker’s perspective controls the details and emphases that affect how readers experience and interpret a text.

Big Idea: Figurative Language

ENDURING UNDERSTANDING: Comparisons, representations, and associations shift meaning from the literal to the figurative and invite readers to interpret a text.

Big Idea: Literary Argumentation 

ENDURING UNDERSTANDING: Readers establish and communicate their interpretations of literature through arguments supported by textual evidence.

Once your list of practice questions is complete, check out our Ultimate List AP® English Literature Tips for some pointers.

Now that you’ve developed a study plan for the multiple choice section, it’s time to tackle the FRQs. You should have self-scored your essays using CollegeBoard’s scoring guidelines . If you notice that there is one particular prompt you struggled with, use Albert’s AP® Lit FRQ Approach Guide to help hone your skills!

Check out Albert’s AP® Lit FRQ prompts for more practice!

If you didn’t struggle with a particular prompt as much as you did a particular part of the rubric, try to figure out what went wrong. Does your thesis restate the prompt instead of proposing your own position? Did you generalize too much? Did you remember to provide evidence but forget to augment it with commentary and analysis? Maybe your word choice wasn’t varied enough to earn the sophistication point.

Whatever element you struggled with, have a look at our comprehensive page dedicated to AP® Lit for some expert advice!

Once you’ve developed an effective study plan using the links and practice above, and you’ve identified the skills which need more practice, it’s time to set your plan in motion. Check and mark your calendar. How many days, weeks, or months do you have until your exam? Pace your studying according to this time-frame. Pro-tip: If you only have a few weeks or days to go, prioritize the skills that you scored the lowest on. 

About halfway through your study schedule, plan to take a second practice test to check your progress. You can either have your teacher assign another full-length Albert practice test or use one of the additional practice tests included in whatever AP® English Literature and Composition review book you purchased. Use these results to inform the rest of your study schedule. Are there skills that you improved on or scored lower on this time? Adjust accordingly, and use our tips in the next section to guide you.

AP® English Literature and Composition Review: 15 Must Know Study Tips

5 AP® English Literature and Composition Study Tips for Home

1.  read as much as possible..

And read widely. Read everything from epic poetry and Victorian novels to New Yorker articles and album reviews to Buzzfeed-style listicles. Read a combination of high and lowbrow texts to make your knowledge more worldly and syncretic.

Make a schedule for personal reading time and stick to it. Reading widely, of course, has incalculable benefits that will not only help you score a 5 on the test but also strengthen your academic performance across the board. 

Reading will help you develop a more impressive vocabulary and a better understanding of varied sentence structure and syntax. The more you read, the better equipped you will be to score a 5 on this exam.

2. Become familiar with the Western Canon.

The Western canon, often referred to simply as “The Canon,” is the body of high-culture literature, music, philosophy, and works of art that is highly valued in the West, i.e., the poems, prose passages, and drama selections that you will mostly see on the AP® Lit exam. 

The canon contains the “classics,” so to speak, and it includes everything from Homer to Junot Diaz. Cultivating a basic understanding of these texts and their authors will not only familiarize you with the history and development of the English tradition but also strengthen your understanding of the so-called “conversation of literature,” the innumerable and complex ways that authors and their works speak to each other and interact. We recommend reading at least the first chapter of Harold Bloom’s book on the subject to get a basic understanding. 

We also insist that you familiarize yourself with the various problems that the perseverance of such a canon produces. During the 80s and 90s, a canon war of sorts took place among English departments, with progressives aiming to dismantle the canon on the grounds that it neglects many African-American, female, queer, and impoverished writers in favor of spotlighting “dead white males.” 

This friction between advocates and opponents of the canon is extremely important to the history and status quo of literary criticism, and understanding this battle will deeply enrich your understanding of literature and increase your chances of scoring a 5 on the exam.

3. Read Thomas Foster’s How To Read Literature Like a Professor .

This book is a lively and entertaining introduction to the tools frequently used in literary criticism, including symbolism, theme, context, irony, and more. It is an excellent way to begin thinking deeply about literature, and it offers clear examples of close-reading.

It also discusses a wide variety of works that will help familiarize you with the canon. It’s very accessible too. Buy it, read it, mark it up, and keep it by your side throughout class. It’s a great tool. 

4. Make flashcards.

You will need to have a strong understanding of different literary devices, authors, works, and rhetorical techniques, and you don’t want to waste time scrambling for definitions on the day of the exam. 

Make yourself some flashcards with the most common literary devices, authors, works, and rhetorical techniques, and carve out at least 30 minutes per day to review. If you’d prefer to use an online resource, make some flashcards over at Quizlet ! 

5. Form study groups!

The beauty of reading literature is that it often produces different and conflicting responses in people, so discussing literature with your friends is a good way to explore new and diverse perspectives. 

What you bring to a text, for instance, may be completely different from what your friend or peer brings. Discussion is a great way to comprehend and investigate difficult works. And it’s also pretty fun!

5 AP® English Literature and Composition Multiple Choice Study Tips

1. practice, practice..

Practice answering multiple choice questions as often as you can. AP® English Literature and Composition multiple choice questions will address either fiction, poetry, or drama, and they will ask you to identify and analyze various literary devices, techniques, and motifs. So study these very devices. If you find yourself totally stuck, consult our guide on how to tackle the multiple choice section . 

2. Sharpen your close-reading skills.

The true key to acing the multiple choice section of this exam is staying engaged with the passages provided to you and actively reading. That means staying alert through the passages, marking them up, and engaging with them directly, not passively skimming them.

Find a method of active reading that works best for you. Some like to mark up the passage extensively, while others prefer to just read the passage twice and take notes here and there. Select which method works for you and go with it. However, do not just choose the easy or lazy way out. You’ll regret it later when you receive your scores. 

3. Look over the questions before reading the passage.

This is often a semi-controversial piece of advice because it doesn’t work for all readers. But it can be helpful if you’re someone who gets easily distracted when reading old prose passages or difficult poetry! 

If you find your mind wandering when reading AP® Lit passages, glancing at the questions beforehand can give your brain a purpose to focus on and a point of entry into the passage. It’s always easiest to begin searching when you know what you’re looking for.

4. Use process of elimination.

Often, an AP® Lit multiple choice question will have one or two answer choices that can be crossed off pretty quickly. So try and narrow your choices down to two possible answers, and then choose the best one. 

If this strategy isn’t working on a particularly difficult question or it seems to hold you up longer than you’d like, it’s perfectly okay to circle it, skip it, and come back to it at the end. Do not get hung up on eliminating choices. Rather, use this strategy to make your reading more efficient and quicker. 

5. It doesn’t hurt to guess.

Obviously, while guessing on every single question isn’t a good strategy and will lead to a 1 on the exam, an educated guess on particularly difficult questions that you truly don’t know how to answer can help. You are scored only on the number of correct answers you give, not the number of questions you answer, so it makes sense to guess on questions that you seriously have no idea how to answer.  

5 AP® English Literature and Composition FRQ Study Tips

1. practice your writing skills by answering questions from collegeboard’s archive of past exam questions or explore our free response practice modules ..

Typically, the same skills are assessed from year to year, so practicing with released exams is a great way to brush up on your analysis skills, and our review practice allows you to pinpoint skills you may need help with.

2. Explore and use the rubric!

The best part about the updated AP® English Literature and Composition revised rubrics and scoring guidelines is that it’s very clear to discern which elements are needed to earn full credit for your essay. Granted, it can be tough to include each element—especially that tricky sophistication section—but the rubric’s outline offers a clear and concise portrait of the perfect essay .

Be sure to construct your thesis statement into a clear and definable interpretation. Provide specific evidence and compelling commentary that supports your thesis. If you check these boxes, then you will have a much greater chance of developing a clear and defensible interpretation. 

3. Pay attention to the task verbs employed in your free response prompts .

Task verbs are verbs that essentially indicate what it is you should do in your free response. The three common task verbs include: 

• Analyze: Examine methodically and in detail the structure of the topic of the question for purposes of interpretation and explanation.
• Choose: Select a literary work from among provided choices.
• Read: Look at or view printed directions and provided passages.

4. Have a solid understanding of literary devices.

Most of the FRQ’s require you to not only specifically identify a passage’s array of literary and rhetorical devices but also analyze and unpack how those devices construct mood, meaning, tone, and more. Study up, read the aforementioned Foster book , and take a look at our list of 15 Essential Rhetorical Terms to Know For AP® English Literature . 

5. Fine-tune your thesis statement.

Your thesis statement is arguably the most important sentence in your essay. It informs the reader of your central argument and summarizes your interpretation, and it sets the tone for the rest of your essay. It is imperative that you master the tricky art of the thesis statement before taking your exam. 

Many university writing centers offer online education on thesis statements that can prove extremely beneficial. Consult UNC Chapel Hill’s thesis statement handout for extra help!

The AP® English Literature and Composition Exam: 5 Test Day Tips to Remember

Be sure you put at least something in your stomach before taking the exam, even if it might be in knots from nerves. You don’t need to eat a deluxe breakfast of pancakes, eggs, bacon, biscuits, etc. (unless that’s your routine), but you do need to eat at least something . Your brain and your body need the energy. If you’re hungry during the exam, it might be harder for you to focus, leading to a lower score or an incomplete exam.

2. Make sure you know the location of your testing site before taking the test.

You do not want to be scrambling and running around the school trying to find your testing room on the day of the exam. Know your room number and know how to get there. There’s truly nothing worse than running around your school trying to find a room when a hugely-important test is underway. 

If you’re getting a ride from a parent or friend, be sure they know the address beforehand. If you’re taking public transit, check the schedule. If you are taking your exam at your own school, don’t get too comfortable. Be sure you know the room number! This is something small but impactful that you can do to reduce your stress the morning of your exam.

3. Prepare everything you need the night before.

Waking up and scrambling to choose an outfit, find pencils, or make breakfast will just stress you out and put you in a negative headspace. Plan your outfit the night before to reduce stress and have an easy breakfast ready to go.

Being prepared saves time and cuts back unnecessary stress. 

And wear something comfortable. You don’t want to be adjusting your outfit throughout the test. It’ll just be distracting. 

4. Bring mints or gum with you.

The rules say that you can’t have food or drink in the testing room, but mints and/or gum are usually allowed unless it’s against your testing site’s own rules. If you find yourself getting distracted, pop a mint or a stick of gum in your mouth! This can help to keep you more awake and focused.

5. Remember to breathe and just relax.

Seriously, just breathe. If you’ve followed the rest of the tips in this post, listened to your teacher, read up on your literary devices, and done your homework, then you’re well-prepared for this exam. Trust yourself. Know that you have done all you can do to prepare and don’t cram the morning of the exam. Last-minute studying helps no one, and it often just leads to stress!

AP® English Literature and Composition Review Notes and Practice Test Resources

Ap® collegeboard’s official youtube channel.

This YouTube channel provides tons of tips, advice, and strategies for tackling the AP® English Literature and Composition exam. It offers online seminars and classes on a diverse range of Lit-related topics such as plot structure, unpacking symbolism, and crafting strong commentary. The best thing about it is that real-life teachers lead the classes, so they feel very personalized.

If you’re a more visual learner who thrives on video content, then this channel is perfect for you!

How-to Guide for Literary Analysis Essays

While we 100% do not condone using Sparknotes textual summaries to get your way through AP® English Literature, we do recommend taking a look at some of their guides and workshops and using them as supplementary resources. This how-to guide offers a 7-step method of approaching literary analysis that might help you get the ball rolling if you’re totally stuck.

This guide is perfect for anyone needing to brush up on their writing skills or anyone needing to find a solid step-by-step approach to writing the free response questions.

AP® English Literature Jeopardy Game

This online Jeopardy game is not only tons of fun but also super helpful in developing your memory and strengthening your understanding of basic literary elements and devices. It contains categories involving poetry terms, general Lit, syntax, style, and figurative language. It’s a great way to review basic terms for the exam, and you can play with up to ten people through its make-your-team feature.  

This is a perfect review for anyone looking to quickly review literary terms in a fun way.

Ms. Effie’s Lifesavers

If you’re a seasoned AP® English teacher, Ms. Effie (Sandra Effinger) probably needs no introduction! Ms. Effie’s Lifesavers website has helped many AP® Lang and AP® Lit teachers plan effective and thoroughly aligned lessons and assignments. Sandra was an AP® Reader for many years, so she knows her stuff. She has tons of free content on her page, as well as a Dropbox full of AP® English goodies for anyone who makes a donation via her PayPal. You’ll find resources for both AP® Language and AP® Literature here. 

Ms. Effie’s webpage is perfect for all students. Really, it has material that would benefit those looking for quick reviews, deeper analysis of free response questions, or help with multiple choice questions.

Summary: The Best AP® English Literature and Composition Review Guide

Remember, the structure of the AP® Lang exam is as follows:

Because AP® English Literature and Composition is a skills-based course, there’s no way to know what specific passages, poems, authors, or concepts might make it onto the official exam. But, we do know exactly which skills will be assessed with which passages, so it’s best to center your studying around brushing up on those skills!

Use the provided charts to help you understand which skills you should focus on, and use Albert’s AP® English Literature and Composition Course Guide to brush up on your understanding of each skill and its corresponding essential knowledge.

Start with a diagnostic test, either on Albert or with a pencil and paper test via Princeton Review or Barron’s . Once you’ve completed and scored your diagnostic, follow our 7 steps on how to create an AP® English Literature and Composition study plan. 

And remember: start reading now! The more you read, the more equipped you will be to ace this exam. Review the Western Canon, study your literary terms, and begin critically engaging with writers!

Practice answering multiple choice questions on Albert and free-response questions from The College Board’s archive of past exam questions. 

If you’ve followed the rest of the tips in this post, listened to your teacher, and done your homework, you’re well-prepared for this exam. Trust that you have done all you can do to prepare and don’t cram the morning of. Last-minute studying helps no one!

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The Literature Review

• Publications: A World of Information
• Primary, Secondary and Tertiary Sources

Differences Among Reviews

Common types of reviews.

• Beginning Steps and Finishing a Review
• Information Sources: Where to Find Them
• Webinar Recording (20 Minutes, Slides and Quiz)
• Webinar Recording (50 Minutes, Slides and Quiz)

Image:  White puzzle.  Permission by Pixabay.com license .

There are many types of literature reviews.  The purposes of a literature review will vary, and the sources used in one will depend on the discipline and the review's topic.   

Literature reviews may have differences that include:

• Purpose:   The reason or objective of the review.  One review may be to see how much has been published on a topic (a scoping review) while another may to draw new conclusions by combining data from multiple yet similar studies (a meta-analysis).  A student may do a review for an assignment, while a researcher could include a literature review as support in their grant proposal.
• Rigor:   Some reviews may want to achieve a higher scholarly or objective standard, so they include pre-established or inclusion criteria for what publications can be included.  
• Discipline norms:  a literature review for one subject (e.g., history) would be different than another (e.g., medicine).
• Topical or narrative:  by subject or theme of documents included in the review.
• Chronological:  by when the included documents were published.
• Geographical:  by regions that study a concept.

See "Common Types of Reviews" for their definitions and characteristics.

The table below will provide summaries, definitions, and examples of common reviews.

• Types of Literature Reviews (PDF)
• << Previous: Primary, Secondary and Tertiary Sources
• Next: Beginning Steps and Finishing a Review >>
• Last Updated: May 29, 2024 11:22 AM
• URL: https://libguides.fau.edu/literature-review

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• Sports (Basel)
• PMC10302780

Exploring the Relationship between Micronutrients and Athletic Performance: A Comprehensive Scientific Systematic Review of the Literature in Sports Medicine

Hadeel ali ghazzawi.

1 Department Nutrition and Food Technology, School of Agriculture, The University of Jordan, Amman 11942, Jordan; moc.kooltuo@89tadaraj_ranam (M.J.); moc.liamg@idiabolasodnos (S.A.);

Mariam Ali Hussain

2 Department of Psychiatry, College of Medicine and Medical Sciences, Arabian Gulf University, Manama 323, Bahrain; hb.ude.uga@hhamairam (M.A.H.); hb.ude.uga@zmajidahk (K.M.R.); moc.liamg@849ydneslaalwahk (K.K.A.);

Khadija Majdy Raziq

Khawla khaled alsendi, reem osama alaamer, manar jaradat, sondos alobaidi, raghad al aqili, khaled trabelsi.

3 High Institute of Sport and Physical Education of Sfax, University of Sfax, Sfax 3000, Tunisia

4 Research Laboratory—Education, Motricity, Sport and Health, University of Sfax, Sfax 3000, Tunisia

Haitham Jahrami

5 Government Hospitals, Ministry of Health, Manama 323, Bahrain

Associated Data

All data are available in the manuscript.

The aim of this systematic review is twofold: (i) to examine the effects of micronutrient intake on athletic performance and (ii) to determine the specific micronutrients, such as vitamins, minerals, and antioxidants, that offer the most significant enhancements in terms of athletic performance, with the goal of providing guidance to athletes and coaches in optimizing their nutritional strategies. The study conducted a systematic search of electronic databases (i.e., PubMed, Web of Science, Scopus) using keywords pertaining to micronutrients, athletic performance, and exercise. The search involved particular criteria of studies published in English between 1950 and 2023. The findings suggest that vitamins and minerals are crucial for an athlete’s health and physical performance, and no single micronutrient is more important than others. Micronutrients are necessary for optimal metabolic body’s functions such as energy production, muscle growth, and recovery, which are all important for sport performance. Meeting the daily intake requirement of micronutrients is essential for athletes, and while a balanced diet that includes healthy lean protein sources, whole grains, fruits, and vegetables is generally sufficient, athletes who are unable to meet their micronutrient needs due to malabsorption or specific deficiencies may benefit from taking multivitamin supplements. However, athletes should only take micronutrient supplements with the consultation of a specialized physician or nutritionist and avoid taking them without confirming a deficiency.

1. Introduction

Optimal performance is a primary objective for many athletes, and this can be attained by following a suitable exercise protocol and ensuring proper nutrition [ 1 ]. Food is composed of nutrients that are essential for growth, repair, and energy generation depending on the amount that meets the body’s need [ 2 ]. Nutrients are typically categorized into two main groups: micronutrients and macronutrients [ 3 ]. When it comes to athletic performance, the importance of micronutrients should not be neglected [ 4 ]. Athletes are prone to consuming insufficient amounts of micronutrients due to inappropriate dietary habits, especially if they are not matching their physical activity requirements [ 5 ]. By making sure they are receiving adequate levels of micronutrients, athletes can give themselves a competitive edge and maximize the potential of their training [ 6 ]. Micronutrients may boost mental performance, help balance hormones, and keep cognitive performance at its peak [ 7 ].

It is noteworthy to emphasize that sports nutrition is not a one-size-fits-all solution, as each athlete has specific nutritional needs [ 7 ]. Therefore, athletes, nutritionists, and coaches must work together to customize nutritional plans for each athlete to ensure that their athletes/players’ needs are considered properly and they are receiving the sufficient level of nutrients they need to aid in the adaptation to their training and ultimately support optimal athletic performance. The evaluation of the evidence of the impact of micronutrients on the performance of athletes is the main purpose of this comprehensive systematic review paper.

2. Methods and Search Strategy

A comprehensive literature search was conducted using the Web of Science, Scopus, and PubMed databases. In order to retrieve relevant studies on the topic, our search strategy incorporated keywords including “micronutrients”, “vitamins”, “minerals”,” antioxidants”, “athletes”, “sport performance”, “training”, and “exercise”. Original research articles involving human subjects, English-language publications, human subjects, and a focus on micronutrients and athletic performance were the inclusion criteria. For the systematic review procedure, the Synthesis without meta-analysis (SWIM) recommendations were followed. The search was limited to articles published between January 1950 and 31 March 2023. The studies that made the cut for the review had to measure outcomes related to athletic performance, have a sample size of at least 10 participants, and use an intervention involving a micronutrient supplement. Studies that concentrated on macronutrients—such as carbohydrates and protein—were disregarded.

2.1. Data Extraction

Studies’ titles and abstracts located by the search were examined by two independent reviewers. After that, full-text articles were examined to see if they qualified for inclusion in the review. Data on the study design, sample size, intervention protocol, micronutrient supplements used, athletic performance outcomes assessed, and outcomes were extracted from the eligible studies.

2.2. Data Synthesis

To summarize the conclusions of the included studies, a narrative synthesis was carried out. The studies’ findings were categorized by micronutrient supplement and athletic performance outcome measures. A description of each study’s design, sample size, intervention strategy, and findings was included in the synthesis. It is important to ensure the accuracy and reliability of a systematic review by ensuring that all information is extracted in a standardized and consistent manner. In this study, two authors independently extracted all information from each paper to minimize the risk of bias and errors. This approach helps to ensure the validity of the review’s findings and strengthens the overall quality of the study. By having two authors independently extract information from each paper, the review can ensure data accuracy and increase confidence in the conclusions drawn from the analysis. It is a rigorous method that is commonly used in systematic reviews and emphasizes the importance of transparency and objectivity in research [ 8 ].

A total of 231 articles were obtained involving 18,683 athletes. Table 1 provides a summary of the main micronutrients researched in sports medicine. Table 2 provides a summary of all available 217 research articles about micronutrients and sports performance. Figure 1 simplified the model of micronutrients’ main functions in sports medicine.

Model of micronutrients’ main functions in sports medicine.

Dietary Difference Intake and Top Sources of Vitamins and Minerals.

Abbreviations: µg: microgram; DNA: deoxyribonucleic acid; IU: international unit; mg: milligram; ROS: reactive oxygen species.

Comprehensive overview of articles about micronutrients and sport performance.

4. Vitamins

Vitamins are organic essential compounds that cannot be synthesized by the human body [ 29 ]. They play a vital role in numerous functions that are relevant to the athlete’s performance [ 7 ]. Their functions are evident in co-enzymes, hormones, and autoxidation, as well as their contribution to energy production [ 242 ]. There are thirteen various kinds of vitamins currently divided into two major groups due to their chemical and biological functions, four of which are fat-soluble vitamins (FSV) including vitamins A, D, E, and K, and the rest are water-soluble vitamins (WSV) including B complex vitamins and vitamin C [ 243 ]. Table 1 summarizes the recommendation requirements of vitamins along with the rich sources and their roles in exercise performance.

5. Fat-Soluble Vitamins (FSV)

Vitamin A plays a significant role in promoting the overall wellbeing of athletes, as it aids in the formation of healthy tissues and improves oxygen access throughout the body, thereby supporting the maintenance of an adequate level of physical activity [ 3 ]. It also has a crucial influence on vision, skin health, and immune system functioning [ 29 ]. Moreover, vitamin A is a potent antioxidant that helps in neutralizing free radicals generated by oxidative stress during advanced physical training. The sufficient consumption of vitamin A may help alleviate the reactive oxygen species and avoid the onset of illnesses such as heart failure and muscle damage [ 244 ], as mentioned in many studies in Table 2 .

Vitamin A mainly exists in two forms: animal source (retinol) and plant-based provitamin A (carotenoids). The intake of sufficient amounts of beef liver, eggs, dairy products, and seafood as well as dark leafy green vegetables may ensure meeting the dietary requirements for athletes. It is noteworthy that athletes may benefit from supplementation with multivitamins that contain vitamin A, as a part rather than its own sole use [ 29 ].

Vitamin A has been proved to enhance and support various body functions, including reaction time, muscles recovery [ 245 , 246 ], and protein synthesis, which is essential for muscle growth and recovery and can be important for those competing in events requiring fast reflexes [ 247 ]. Furthermore, vitamin A can help protect athletes against injuries by increasing healing times and promoting the formation of healthy connective tissues [ 3 ]. Finally, vitamin A may help fight off colds, flu, and other illnesses, which can be particularly helpful for traveling athletes.

To evaluate the effect of crocetin on fatigue, a study test was conducted by athletes to measure stamina using a bicycle ergometer at a standard workload for 120 min twice. They also performed non-workload tests of 10 s at 30 min at a maximum velocity (MV) [ 242 ]. A difference in MV from 30 to the 210 min test was remarkably reported only in men who consumed crocetin when compared to their counterpart who used a placebo ( p < 0.05) [ 248 ]. No difference was observed with the consumption of ascorbic acid in all candidates with the same period [ 248 ]. The daily consumption of crocetin would reduce physical exhaustion in men, according to these results [ 179 ]. The attenuating effect of saffron carotenoids on muscle fatigue is due to their provitamin A activity [ 248 ]. Athletes should meet their daily recommended intake of vitamin A to guarantee a perfect peak physical condition [ 249 ].

The Recommended Dietary Allowance (RDA) of retinol activity equivalents (mcg RAE), as shown in Table 1 , is 900 micrograms for men aged 19 years old and older, equal to 3000 international units (IU), and 700 mcg RAE for women aged 19 years old and older, equivalent to 2333 (IU). However, the adherence to a maximum Tolerable Upper Limit (UL) of 10,000 IU (3000 mcg)/day for adults is important to avoid any dangerous effect. It is also important to emphasize that toxicity may occur when frequent doses of more than 25,000 IU are taken daily [ 3 ].

β-carotene is a member of the carotenoid family that is thought to provide numerous health benefits, including immunity system boosting, antioxidation properties, and performance enhancement [ 250 ]. β-carotene is an essential antioxidant, meaning that it helps prevent the harmful effect of free radicals on cells [ 251 ]. This is important for athletes, as free radicals are generated during strenuous exercise and can lead to fatigue and soreness [ 176 ]. Several studies have reported similar findings, highlighting the ability of vitamin A to potentially reduce recovery time from exercise [ 7 , 250 ]

Sumac juice drink was tested in a study to evaluate its impact on pain scores through post-exercise intervals. Forty healthy candidates involved in an aerobic training protocol for four weeks received a dose of placebo or sumac juice consumption two times/day for a month. The results revealed that participants of the sumac juice group had a lower pain score increment and even a better enhancement during pain relief. The potency of protecting muscles might be due to the sumac juice antioxidant potency of β-carotene-linoleic acid components. These results highlight the possibility of sumac juice consumption in improving muscle performance among athletes [ 252 ]. Nevertheless, future studies of athletes are warranted.

Athletes often push their bodies to the limit, therefore compromising their immune systems and making them more susceptible to infections and illness [ 176 ]. Taking a supplement with β-carotene may have potential benefits for the immune system, helping to prevent illness and potentially enabling athletes to train harder and longer [ 250 , 251 ]. Apparently healthy nonsmoker adult males were involved in consuming placebo or 15 mg/day of β-carotene for 26 days. After oral administration, significant increases in the monocytes percentage representing the major histocompatibility complex class II molecule human leukocyte antigen DR isotype (HLA-DR) and the adhesion molecules intercellular adhesion molecule-1 and leukocyte function-associated antigen-3 were observed. Furthermore, tumor necrosis factor-alpha (TNF-alpha) was notably elevated due to the dose intake, arguing that a slight increment in the consumption of dietary β-carotene can enhance the responses of immune cells within the short term, supporting the process of the carcinogenic potency [ 253 ].

Lastly, β-carotene has been found to improve physical performance [ 254 ]. Studies have shown that β-carotene supplementation may lead to endurance strength improvement and injury risk prevention [ 3 , 150 ]. Similarly, a meta-analysis of nine studies including participants from both genders, with a total 190,545 candidates, emphasized that β-carotene leads to a significant enhancement in overall performance [ 29 ]. There was a 95% possibility that β-carotene consumption attenuates the possibility of hip fracture and other different fracture types by over 20% [ 251 ]. According to research, despite the uncertain effect of the antioxidant’s supplementation, consuming β-carotene and combining antioxidants or not still has an effective impact in reducing exercise-induced peroxidation [ 33 ]. This may enhance athletes’ endurance in the long term [ 251 , 254 , 255 ].

6. Vitamin E

As research progresses, the potential advantages of vitamin E for athletes are becoming increasingly apparent. Vitamin E helps in protecting athletes’ bodies and may improve both performance and recovery [ 75 ]. Overtraining and intense exercise are associated with reactive oxygen species (ROSs) production, which aids in enhanced muscular and endurance adaptation to exercise through the upregulation of endogenous antioxidant enzymes [ 256 ]. However, excess accumulation of ROS accompanied by the inability of the body to scavenge these compounds is harmful to the body’s cell components which is associated with fatigue, delayed recovery, and reduced performance [ 257 ]. Accordingly, research suggests the possible protective effects of vitamin E supplements against chronic stress associated with exercise [ 257 , 258 ]. This vitamin possesses antioxidant properties by neutralizing free radicals, protecting cells and tissues [ 257 , 258 ].

Studies showed controversial results of vitamin E supplementation in athletes [ 44 ]. It was shown that vitamin E supplements neither inhibit exercise-induced oxidative stress nor impact endurance running performance [ 259 ]. Moreover, these results were supported by the randomized controlled trial on athletic students where vitamin E oral consumption was found to not influence exercise endurance [ 260 ]. On the other hand, among healthy individuals, vitamin E (alpha-tocopherol) consumption inhibits the exercise-induced reduction in blood paraoxonase 1/arylesterase activity [ 6 , 44 , 147 , 260 ]. Excess doses of supplements have been shown in studies to inhibit the signaling reactions required for adaptations to exercise, creating an interference effect [ 3 ].

A meta-analysis revealed that vitamin E supplements have a beneficial and protective effect, particularly at low doses (≤500 IU/day), in reducing biomarkers associated with exercise-induced muscle damage and oxidative stress. Beneficial effects of the antioxidant characteristics of vitamin E were observed among exercise-induced side-effects [ 257 ]; both animal and human studies have indicated that Vitamin E has the potential to enhance immune function and provide protection against various infectious diseases [ 6 ]. Vitamin E reduces PGE2 production and inhibits COX2 activity, likely by decreasing nitric oxide production [ 261 ]. Furthermore, it improves T cells immune synapse formation and activation signals, and lastly, it helps in modulating the T (Th1/Th2) balance [ 52 ]. This is particularly beneficial for athletes, who are often susceptible to illness and injury due to the intense physical demands of their sport. By supplementing with vitamin E, athletes can help increase the body’s natural immunity, thus reducing the risk of infection and promoting recovery [ 262 ].

Vitamin E may assist in improving blood flow, which is essential for athletes [ 242 ]. γ-tocopherol, which is one of the compounds that contain vitamin E, increases cardiovascular functions. γ-tocopherol expands the activity of nitric oxide synthase, which in turn produces nitric oxide, aiding in vessels relaxation and thus improving blood flow [ 29 ]. Adequate levels of nutrients and oxygen concentrations in muscles indicate a raised blood flow rate, which may help improve performance [ 263 ]. Additionally, vitamin E improves red blood cells’ flow and flexibility [ 264 ]. This is important for athletes, as improved blood flow means better performance in delivering nutrients and oxygen to the muscles, allowing them to perform at their best [ 176 ].

Free radicals such as superoxide, nitric oxide, and hydrogen peroxide are known to be of significant importance, as there must be a balance between antioxidants and free radicals in order to obtain physiological muscle adaptation in response to exercise [ 25 ]. Few studies suggested that antioxidants supplementation may be beneficial under specific circumstances, such as overtraining, high-altitude training, or hypoxic training, and claimed that antioxidant usage such as the intake of vitamin E or vitamin C may have no benefit at all or may even cause harm [ 6 , 7 , 29 , 176 , 256 ]. Misusing or consuming excessive amounts of vitamins can lead to muscle fatigue and impede the recovery process due to the inactivation of the gene expression regulator Nrf2 (Nuclear factor erythroid 2-related factor 2), which plays a role in the response to cellular stress and contributes to enhancing exercise performance [ 265 ]. It is worth noting that Vitamin E toxicity may cause increases in mortality risk factors, since there has been a positive relation accompanied by a high-sensitivity C reactive protein indicative of inflammation [ 266 ].

7. Vitamin D

Vitamin D plays a cooperative role in the synthesis of various hormones in the body [ 3 ]. Dairy products, egg yolk, and fatty fish are the rich dietary intake sources [ 2 ]. Moreover, it can be synthesized in vivo and be activated by sunlight within a duration of 15 to 20 min of exposure [ 44 ]. It also plays an important role in calcium homeostasis and constant healthy bone [ 30 ], functions of improving the immune system, musculoskeletal system, power, and force output [ 45 ].

Vitamin D supplementation has been increased among athletes [ 45 ]. Unfortunately, the widespread vitamin D insufficiency has been clearly stated in elite male athletes, with evidence of a deficit in women [ 46 ]. Percentages of insufficiency in elite athletes were above 50%, and the deficiency in other studies was 70–90%, as reported by Harju et al. [ 47 ]. Certain circumstances impact vitamin D status, such as indoor training, pigmented skin, and living in a high-altitude region [ 48 ]. Studies have reported that athletes with vitamin D deficiency may experience ergogenic benefits when taking vitamin D supplements [ 103 ].

There was a direct relation between the concentrations of vitamin D and athletes’ performance, such as speed, jumps’ height, power muscle tone, and strength of handgrip [ 50 ]. Moreover, the addition of calcium to vitamin D supplements exhibited a reduction in the stress fracture rate [ 106 , 138 ].

In a study conducted among 70 athletes randomly assigned for 8 weeks to either vitamin D oral supplements of 50,000 IU/week group or a control group, a significant improvement in the test of the strength leg press in both groups was reported [ 267 ]. However, the results emphasized that the enhancement in the supplemented group was obviously more noted than that in the control group ( p = 0.034). Moreover, when the sprint test was conducted, within-group enhancement had been noticed in the supplemented group only ( p = 0.030). The results showed that regular weekly vitamin D supplementation with a dose of 50,000 IU increased the levels of circulating calcidiol (major circulating form of vitamin D) by approximately 17 ng/mL. This increment was related to a notable enhancement in sprint and power leg examinations in the vitamin D group [ 138 ]

Additionally, vitamin D is also thought to improve the body’s utilization of carbohydrates during exercise, providing the body with increased energy, which can help to enhance performance [ 1 ]. Twenty-two male adult athletes were allocated into two groups for 8 days: a one-shot dose of 150,000 IU vitamin D group and a placebo group. The vitamin D group showed a significant elevation in muscle power in the period from day 1 up to day 8, suggesting that a single dose of 150 000 IU vitamin D had a beneficial impact on serum 25-hydroxy vitamin D (25(OH)D) levels and the muscle’s role [ 268 ].

To maintain sufficient vitamin D levels, the most appropriate way is to spend time in outdoor direct sunlight for several minutes each day, as obviously indicated by many studies’ conclusions (see Table 2 ). This prescription for sun exposure should also be combined with foods that are rich in vitamin D, such as dairy products, fatty fish, and fortified foods [ 101 ]. Additionally, athletes may also benefit from daily multivitamin supplements that contain vitamin D to ensure that their body receives the best possible nutrition. The recommended daily dose of vitamin D, as shown in Table 1 , varies depending on age; a daily dose of 600 IU (equivalent to 15 micrograms (mcg)) is considered sufficient for the age of 19 and above in both genders, and for adults over 70 years old, an 800 IU (20 mcg) daily dose would be sufficient [ 7 , 25 ]. Vitamin D-deficient athletes would require 50,000 IU of vitamin D per week for 8 weeks [ 138 , 258 ].

A previous study was conducted for 12 weeks among 53 youth athlete swimmers who suffered from insufficient levels of vitamin D to evaluate the influence of vitamin D oral supplementation on physical performance by taking 2000 IU/day of vitamin D or placebo. No notable difference was observed in performance between the supplemented and placebo groups [ 269 ]. The results concluded that there was no remarkable correlation found between Vitamin D levels and the evaluated criteria including strength or swimming performance and even the age-adjusted balance. Although the oral administration of vitamin D had raised the concentration of Vitamin D compared to the placebo group, no significant physical performance enhancement was reported [ 269 ].

8. Vitamin K

Vitamin K is essential for blood coagulation [ 163 ]. It may also impact bone metabolism in postmenopausal women, according to a few previous studies [ 3 , 7 , 270 ]. In elite female athletes, the oral intake of vitamin K at a dose of 10 mg/day has been shown to improve bone remodeling [ 254 ] by increasing the calcium-binding capacity of osteocalcin, promoting bone formation, and reducing bone resorption [ 176 ]. Moreover, the intake of vitamin K improved cardiovascular function [ 18 , 231 ]. Table 1 summarized the recommendation and the role of vitamin K in exercise performance.

9. Water-Soluble Vitamins (WSV)

B-complex vitamins are essential for athletes to maintain optimal health and performance [ 19 ]. B-complex vitamins help athletes manage stress and anxiety, aid in muscle recovery, and reduce fatigue, which may adversely affect performance if left unchecked [ 2 ]. B-complex vitamins help in blood pressure regulation [ 271 ]. Moreover, B-complex vitamins aid in maintaining a healthy sleep schedule by regulating levels of the sleep-regulating hormone melatonin, helping athletes fall in a deep continuous sleep [ 5 ]. This is essential for athletes, as the lack of sleep can affect an athlete’s performance [ 52 ]. B-complex vitamins also contribute to maintaining optimal health and performance in athletes, supporting improved brain functioning, concentration, sleep quality, and energy levels [ 19 ]. Thus, athletes need to ensure that they are receiving enough vitamin B through their diet or supplements [ 244 ].

Thiamine (B1) is a water-soluble vitamin that must be consumed regularly from the diet [ 6 ]. Although free thiamine is stable at acidic pH, it is destroyed by ultraviolet (UV) and gamma irradiation and is heat-sensitive [ 29 ]. Whole grains, bread, and nuts are the most common thiamine food sources, while milled wheat flour, polished rice, vegetables, and fruits contain less thiamin [ 272 ]. The large intestine’s bacteria in the human body are able to produce thiamine and thiamine pyrophosphate (TPP) [ 52 ]. Thiamine leaches into the water due to its solubility and is inevitably lost in any discarded soaking or cooking water, as well as destroyed by heating during culinary methods [ 7 ].

Thiamine, in its active state (TPP), is a cofactor of numerous important enzymes involved in the metabolism of carbohydrates and branched-chain amino acids [ 7 ]. Moreover, it is necessary for several other cellular functions, including the development of nucleic acid precursors, myelin, and neurotransmitters (such as acetylcholine), as well as antioxidant defense [ 272 ]. A deficiency of this vitamin leads to a decline in oxidative metabolism [ 265 ]. The biochemical outcomes include a failure to create adenosine triphosphate (ATP), lactic acidosis resulting in a greater lactic acid generation, and a reduction in neurotransmitter synthesis (e.g., acetylcholine, glutamate, aspartate, and gamma-aminobutyric acid (GABA)) [ 6 ]. The major causes of thiamin deficiency are either the insufficient intake, poor absorption or metabolism, or an increase the body demand [ 265 ]. Furthermore, diuretics and diarrhea lead to thiamine deficiency [ 272 ]. Regarding thiamin and exercise, research suggests that thiamin availability in the diet appears to influence exercise capacity when athletes consume the recommended amount [ 254 ].

Riboflavin (B2) is the second vitamin from the B-complex vitamins [ 270 ]. It appears as a yellow-orange chemical molecule that is water-soluble [ 273 ]. Riboflavin is relatively heat- and oxygen-stable, especially in an acidic environment [ 19 ]. It is very light-sensitive, destroyed by reducing agents, and unstable in alkaline solutions [ 4 ]. Riboflavin is essential and must be obtained from food sources [ 2 ]. Riboflavin is abundant in almonds, beef liver, sardines, mushrooms, cheddar cheese, and eggs [ 271 ]. When athletes consume a typical amount of riboflavin, their exercise capability would be optimum [ 254 ].

Niacin (B3) is the third water-soluble member of the B vitamins family [ 176 ]. Humans can partially convert the essential amino acid tryptophan to nicotinamide, which is a dietary supply of niacin [ 270 ]. However, the conversion cannot meet the demands for niacin, so dietary niacin supplies around 50% of the daily niacin requirement [ 256 ]. Meat, whole grains, milk, and dairy products are good sources of niacin [ 242 ]. Niacin is abundant in peanuts, seafood, mushrooms, and yeasts [ 29 ]. Food items high in tryptophan-containing proteins, such as milk, cheese, and eggs, are good sources of niacin [ 7 ]. Its roles include reduction and oxidation (redox) processes, as well as acting as a ligand for a range of purine receptors [ 243 ].

It is hypothesized that this vitamin lowers cholesterol, improves thermoregulation, and improves oxidative metabolism [ 274 ]. In hypercholesteremic individuals, a niacin intake of 100–500 mg/day may help lower blood lipid levels while increasing homocysteine levels [ 176 ]. Nevertheless, consuming 280 mg of niacin during exercise has been demonstrated to reduce exercise capacity by moderating fatty acid mobilization [ 275 ].

Pantothenic acid (B5) is a water-soluble vitamin that is widely available in the diet [ 3 ]. It is often provided as calcium pantothenate, which is more stable against light, heat, and oxygen, but is unstable in both alkaline and acidic circumstances [ 273 ]. Sodium pantothenate is also available, but its use is restricted due to its hygroscopicity [ 272 ]. Pantothenic acid functions as a coenzyme for acetyl coenzyme A (acetyl CoA), implying its importance in aerobic or oxygen-based energy systems [ 2 ]. Acetyl CoA supplementation has not been shown to increase aerobic performance in studies [ 25 , 52 , 202 , 276 ]. Yet, one study found a reduction in the lactic acid buildup, but no benefit in performance was concluded [ 277 ].

Pyridoxine (B6) is marketed as a supplement that increases muscular growth, strength, and aerobic capacity in the lactic acid and oxygen systems [ 141 ]. It might additionally have a relaxing effect, which has been related to increased mental power [ 24 ]. Surprisingly, research showed that pyridoxine did not increase the capacity of aerobic exercise or the accumulation of lactic acid in well-nourished athletes [ 23 ]. However, when paired with vitamins B1 and B12, it has been shown to raise serotonin levels and enhance motor abilities, which are required in sports such as pistol shooting and archery [ 24 ]. Moreover, vitamin B6, thiamin, and pantothenic acid showed inverse relationships with stress risk and anxiety [ 25 ]. Another study revealed that after a month of vitamin B6 intake, young adult athletes reported feeling less anxiety [ 25 ]. Table 2 presents studies that investigated the effect of vitamin B6 intake either as part of a multivitamin supplement or as a sole intake on exercise performance. Most of the studies reported a positive impact on exercise performance, particularly in cases of vitamin B6 deficiency.

Cyano-cobalamin (B1 2) is a coenzyme required for the synthesis of deoxyribonucleic acid (DNA) and serotonin [ 176 ]. In theory, it would enhance muscular mass and blood oxygen-carrying capacity and lessen anxiety [ 273 ]. However, no ergogenic impact has been documented in well-nourished athletes [ 242 ]. Interestingly, it may enhance pistol shooting performance due to the stimulation of serotonin production, which reduces anxiety [ 2 ]. A cross-sectional research work studied 100 amnestic mild cognitive impairment (MCI) patients characterized by low-normal and high-normal vitamin B12 levels, who were then enrolled in an Auditory Verbal Learning test to evaluate their memory’s function. The results showed that those with low-normal B12 concentrations had notable defects in learning and recognition abilities and even in memory performance due to the low microstructure integrity of the hippocampus [ 23 ]. It is important to acknowledge that vitamin B12 is crucial for proper brain functioning, as it aids in faster information processing and enhances concentration levels [ 21 ]. This has been demonstrated in patients with mild cognitive impairment (MCI) who had low-normal levels of vitamin B12 [ 262 ]. This is especially important for athletes, as improved brain functioning may help improve performance in many ways, from learning new techniques to continuous focus maintenance during long competitions [ 24 ].

Folic acid (folate) is a coenzyme that aids in the synthesis of DNA and red blood cells [ 278 ]. An increased red blood cell count enhances oxygen supply to muscles during exercise [ 21 , 79 ]. It is thought to be crucial in preventing birth abnormalities and may lower homocysteine levels, which is a risk factor for heart disease [ 22 ]. Folic acid supplements did not increase exercise performance among malnourished athletes with folate deficiency [ 254 ].

10. Vitamin C

Vitamin C (also known as ascorbic acid) can be found in many types of food, including oranges, strawberries, broccoli, and sweet potatoes [ 15 ]. Athletes require more vitamin C than the average person since their bodies are working harder and being pushed to the limits [ 15 , 279 ]. Therefore, they need to receive enough of this vital nutrient to perform at their best. Researchers have reported that the intake of vitamin C supplements does not boost physical performance in well-nourished athletes [ 52 ]. Nevertheless, athletes are recommended to receive an adequate amount of vitamin C from their balanced diet.

The crucial role of vitamin C in neutralizing free radicals has been raised from its antioxidative potency [ 69 ], thereby improving the immune system [ 15 ] and reducing the risk of illnesses such as colds and other viruses [ 280 ]. It plays an important role in immunity by enhancing the differentiation and proliferation of B and T lymphocytes and increasing antibodies levels [ 25 ]. Furthermore, vitamin C has been reported to modulate cytokine production and decrease histamine levels [ 169 , 281 ]. Studies have also shown that vitamin C can eliminate fatigue, improve coordination, and increase endurance [ 15 ].

Vitamin C has a crucial role to play in wound healing and collagen production [ 3 ]. It helps boost energy levels and protects the body from illnesses and injuries [ 242 ]. Vitamin C works as a co-factor to produce collagen for the propyl and lysol hydroxyls enzymes, which stabilize the structure of collagen [ 29 ]. Furthermore, vitamin C also enhances collagen gene expression in fibroblasts [ 7 ], contributing to the strength and integrity of joints and muscles, which is essential for the success of any athlete. This is supported by the fact that vitamin C is crucial in protecting against ROS damage, enhancing keratinocyte differentiation, lipid synthesis, fibroblast proliferation, and migration, which has been seen to shorten the time of wound healing [ 28 , 282 ].

However, high levels of vitamin C can, in turn, act as a pro-oxidant rather than an antioxidant [ 29 ]. The overconsumption of vitamin C supplement decreases exercise-induced adaptation, delays post-exercise recovery, increases lipid peroxidation, and diminishes mitochondrial biogenesis [ 127 ]. These effects can hinder skeletal muscle adaptation to exercise [ 3 ].

11. Minerals

Numerous physiological and metabolic processes in the human body involve minerals [ 283 ]. Minerals have physiological effects on the body during exercise, including maintaining a normal heartbeat, oxygen transportation, antioxidation activity, healthy bone, and immune system enhancement [ 283 ]. Sufficient levels of minerals are required for optimal performance because many of these processes are enhanced during sports activity [ 284 ]. For athletes to perform at their best, maintaining a healthy body necessitates the intake of a variety of nutrients. Some minerals make weightlifting more effective by enhancing athletic performance; these are the minerals that degrade faster when used in sports endeavors [ 285 ] and thus need to be replaced routinely among athletes to sustain their performance. Table 1 summarized the recommendation requirements of minerals along with the rich sources and their roles in exercise performance.

Iron (Fe) is a crucial mineral for physical performance, and its importance cannot be overstated [ 286 ]. When it comes to peak performance, an adequate intake of iron can make all the difference [ 149 ]. It helps the body produce red blood cells, which are necessary for transporting oxygen to the muscles [ 71 ]. Without enough iron, athletes and other physically active individuals may suffer from fatigue and lethargy as the body struggles to meet the increased demands [ 71 ]. A huge part of the pool of plasma iron (almost 80%) is utilized by the bone marrow; this is equivalent to a 20–30 mg/day dose to ensure the efficient production of erythrocyte [ 31 ].

In addition to red blood cells production, iron is also important for energy metabolism [ 31 ]. It is necessary for converting food into energy, and it helps to ensure that the body can use energy efficiently for physical activities [ 280 ]. Iron also helps the body in regulating its temperature, making it an essential nutrient for athletes competing in warm climates or hot weather [ 149 ]. Finally, it is important for other bodily functions, such as the immune system, growth, and hormone production [ 284 ]. When considering physical performance, it is important to ensure that iron intake is adequate and balanced. The human physiological mechanism preserves the maximum iron [ 29 ]. Based on the total compulsory iron depletion that occurs daily and the average of 10% absorption and bioavailability, the World Health Organization (WHO) and other national institutes have estimated iron-recommended doses depending on several characteristics including gender, age, and race. The recommended dietary intake for females is 18 mg, and for males, it is 8 mg [ 31 ]. Poorly planned diets, coupled with inadequate levels of exercise, can lead to anemia and other problems associated with low iron levels [ 286 ]. This may cause fatigue, poor performance, and a decreased ability to perform physical activities [ 285 ]. Therefore, it is necessary to consume a high-quality variant diet that involves iron-rich sources [ 284 ].

It is also important to make sure that athletes have enough time to rest and recover between workouts. Iron helps to replenish energy stores and reduce fatigue, so it is important to give the body time to absorb the nutrient [ 287 ]. Additionally, certain supplements may also help in providing additional iron to meet the demands of physical performance [ 205 ]. Athletic training can result in alterations including higher vascularization (creation of new blood vessels), elevated hematocrit, and higher erythrocyte awareness in the blood, which may lead to an increase in iron needs [ 122 ]. A shortage of iron may result from hemorrhages, gastric blood loss, and/or urinary tract bleeding, especially among high-intensity sports [ 121 ]. Professionals are predicted to have 70% higher iron needs than non-professionals [ 287 ]. Iron deficiency anemia can impede progress in an athlete’s training by reducing oxygen delivery [ 283 ]. Lastly, most research concluded that iron supplements do not enhance aerobic performance, unless there is a specific depletion and/or anemia reported [ 149 ].

13. Calcium

Athletes must be in peak physical condition to perform at their best and make sure their diets are balanced, which is an important part of their training regimen [ 288 ]. Calcium (Ca) is among the many nutrients that athletes need to remain healthy [ 289 ]. It not only helps to keep bones and muscles strong, but it has also been linked to improved performance in athletes [ 32 ]. However, insufficient Ca consumption and elevated Ca depletion may expose a person to osteoporosis [ 194 ]. Athletes should make sure to consume an adequate amount of Ca each day as part of their balanced diet, which would achieve around 1500 mg/d [ 32 , 188 ]. The optimal Ca requirement is 1200 mg/day for adolescents and youth, 1000 mg/day for females aged 25 to 50 years old, and 1500 mg/day for postmenopausal females who are not treated with estrogen replacement therapy [ 33 ]. With the right diet and exercise routine, they may capitalize on the benefits that Ca has to offer and maximize their performance [ 32 , 188 ].

Numerous studies have indicated that the adequate and consistent consumption of Ca can potentially enhance physical performance in athletes [ 289 ], as it plays a crucial role in maintaining muscle strength, which is a key element for exercise performance [ 35 , 289 ]. Additionally, it may help reduce injuries and improve recovery time [ 32 ]. It is also known that Ca may protect the bones and joints from stress caused by continuous physical activity [ 32 ]. Conversely, improving Ca status with 2000 mg of Ca supplementation has been shown to reduce the risk of developing a stress fracture [ 289 ]. Calcium also helps to convert carbohydrates and fat into energy, which can contribute to performance improvement [ 78 , 288 ]. It also helps in reducing fatigue and delaying the onset of muscle soreness [ 290 ].

Calcium can be found in many common foods including milk, yogurt, cheese, and dark leafy greens. Other sources include tofu, nuts, fish, and fortified cereals [ 289 ]. Additionally, athletes may consider Ca supplements if they are unable to receive the recommended daily intake from their diet. It is important to note that the amount of Ca an athlete needs daily may vary depending on their weight and activity level [ 289 ]. Skeletal muscles’ ability to contract and relax depends in part on Ca [ 291 ]. The importance of it binding to troponin C for the contraction of muscles has the potential to influence performance [ 33 ]. While it is true that training leads to higher Ca loss, primarily through perspiration, the foundations of bone mineralization are Ca, vitamin D, and physical activity [ 292 ]. However, in rare circumstances, especially if the diet is low in its nutrient density, physical activity might endanger bones [ 65 ]. Every athlete should place a high priority on developing and maintaining optimal bone health, since vigorous physical activity increases the stress fractures risk [ 85 , 188 ].

14. Potassium

When it comes to athletes’ health and performance, one mineral that is essential to success is potassium (K) [ 293 ]. It is a required nutrient for human health and is necessary for many physiological processes [ 293 ]. Adults should not exceed the consumption of 2000 mg sodium/day (Na) or 5 g of salt and have a minimum dose of 3510 mg potassium/day, according to new guidelines established by the WHO [ 14 , 281 ]. It has a crucial role in muscle contractions and helps the body regulate fluid balance, blood pressure, and the heart rate [ 281 ]. In addition to its role in muscle contractions, it is also involved in nerve functions and proper electrolyte balance [ 59 ], which may be beneficial to athletes who may be sweating during a long practice or game [ 29 ]. Furthermore, proper potassium levels can help prevent injuries and help athletes maintain their energy levels [ 177 , 230 ].

Potassium is a great source of energy for athletes [ 293 ]. It helps to reduce the amount of lactic acid stored in the muscles [ 59 ], which may lead to fatigue as well as maintain a healthy metabolism [ 35 ]. It is also involved in the breakdown of carbohydrates, which helps keep energy levels high during intense physical activity [ 177 ]. It is unknown if potassium supplementation reduces the occurrence of muscular cramping in athletes. It should be acknowledged that there have been no reports of ergogenic effects [ 58 ].

15. Magnesium

Magnesium (Mg) is an essential mineral that is recognized for its critical role in athletic performance and overall health [ 294 ]. Magnesium helps to improve energy levels, reduce fatigue, and even increase muscle performance, making it a vital nutrient for athletes [ 36 ]. With its numerous benefits, magnesium is being increasingly taken by athletes to help them reach peak performance and maintain their physical health [ 294 ]. Magnesium helps to improve energy levels by raising the ATP availability, which is best defined as the gold energy stores of cells [ 283 ]. Deficiency may cause ATP levels to be depleted, resulting in fatigue and overall reduced performance [ 34 ]. The regular consumption of Mg can improve ATP production, providing athletes with increased energy and improved endurance [ 295 ]. The mineral is also important for maintaining muscle performance and reducing fatigue [ 296 ]. It is known to support muscle contraction and relaxation, allowing for better muscle control and improved performance [ 142 ]. It also works to reduce lactic acid buildup in muscles, which may help reduce pain during exercise and improve recovery time [ 297 ].

Moreover, Mg has numerous other benefits that support physical wellbeing. It helps to improve sleep quality, regulate blood sugar, reduce stress, and even support the cardiovascular system [ 294 , 297 ]. By regularly taking Mg, athletes may benefit from improved energy production, reduced fatigue, and improved physical health, allowing them to reach their maximum performance potential [ 36 ]. The Recommended Dietary Allowance (RDA) is 400 to 420 and 310 to 320 mg/day for 14 to over 70 years of age among males and females, respectively [ 294 ].

Magnesium is a versatile mineral that is important for recovery and is found in over 300 enzymes that are involved in energy metabolism [ 297 ]. It is linked to strength training and cardiorespiratory processes, showing a reciprocal relationship between exercise and Mg in the human body [ 142 ]. Exercise controls Mg distribution and usage [ 296 ]. Training triggers Mg to be transferred to areas where energy is produced [ 37 ]. For instance, during prolonged activity, serum Mg may be transferred from serum blood to red blood cells (RBCs) or muscle to support exercise. On the other hand, short-term exercise may result in a reduction in the plasma/serum volume and a rise in serum Mg levels [ 297 ].

Magnesium contributes to the metabolism of energy and supports typical muscular contraction and relaxation [ 283 ]. In male athletes, serum Mg levels are favorably correlated with muscular performance [ 36 ]. Additionally, research suggests a possible connection between Mg deficit and muscle cramps by demonstrating how it might alter neuromuscular function [ 297 ]. Physically active people might need more magnesium to sustain their peak exercise performance than inactive people do [ 283 ]. Low Mg levels may cause ineffective energy metabolism and decreased endurance in individuals who are engaged in a weight training program [ 294 ]. Higher Mg consumption is linked to enhanced cardiorespiratory function and lower oxygen demand during aerobic exercise [ 34 ]. Most studies reported little impact of 500 mg/day Mg on exercise performance in athletes, unless there is a deficit [ 37 , 142 , 296 ]. A study of 16 physically active men who were assigned to 300 mg/day for 14 days of Mg supplementation or a control group concluded no direct impact on exercise performance while using Mg supplementation [ 296 ].

Athletes of all ages and skill levels rely on zinc (Zn) to keep their bodies performing at their peak [ 298 ]. It is an essential mineral that our bodies need for metabolic functions such as cell repair, immune system functioning, hormone production, and healthy skin [ 38 ]. Unfortunately, not all athletes receive enough zinc from food intake, which may leave athletes at a disadvantage [ 38 ]. According to the UK National Diet and Nutrition Survey (NDNS), current daily intakes are 9.5 mg and 7.6 mg for men and women, respectively [ 299 ]. The survey has also shown that 6% of men and 7% of women do not receive enough zinc in their diet, putting them at a greater risk of deficiency [ 300 ]. Fortunately, there are many benefits athletes may reap from adding zinc supplements to their routines [ 300 ].

One notable benefit of zinc supplementation is the improvement in athletic performance [ 281 ], as it reduces blood viscosity and enhances oxygen delivery, thereby boosting aerobic endurance [ 38 , 281 ]. Zinc helps to increase strength and endurance, so athletes may push their bodies to the limit while still receiving the nutrients they need [ 298 ]. A double-blinded cross-over study featuring 16 female athletes was conducted to estimate muscle strength and endurance [ 38 ]. The participants consumed 135 mg/day of Zn for 14 days and showed remarkably higher dynamic isokinetic strength and angular speed [ 29 ]. Additionally, Zn may help to reduce inflammation and soreness, which can accelerate recovery time and reduce the risk of injury [ 59 ]. Zinc may also help in improving attention and focus [ 60 ]. This can assist athletes in staying focused on their tasks and performing at their best. Zinc is a vital mineral for athletes of all ages and abilities [ 273 ]. Including it as a supplement to their regimen may help enhance strength, endurance, and focus while also reducing inflammation and supporting the immune system [ 92 ].

In addition, Zn may help to boost the immune system, making it easier for athletes to fight off colds and other illnesses that can stall their progress by increasing neutrophils’ ability to produce ROS after exercise [ 7 ]. It has been indicated that Zn oral consumption of 25 mg/day while exercising can reduce exercise-induced changes in immune function to the minimum [ 298 ]. Moreover, Zn may help support healthy vision and keep skin healthy, both of which are important for optimal performance [ 258 ]. Zn impacts the formation and efficient functioning of the skin and mucous membranes [ 298 ]. It helps maintain skin cell membranes, and it plays a part in cell mitosis and differentiation; moreover, it has an essential role in the survival of keratinocytes [ 215 ] and even in protecting skin against induced UV radiation damage [ 301 ]. Lastly, taking Zn supplements may help athletes meet their nutritional goals without having to increase their caloric intake, making it an ideal supplement for those who are trying to stay lean [ 6 ]. Despite Zn supplements being popular among athletes, there is limited proof regarding athletic performance improvement in a period of 1–6 weeks, as shown in the study of Polat, 2011 [ 302 ].

To detect the actual impact of zinc oral consumption on the hematological parameters, a study included 24 male kickboxing athletes, who were separated to form the three following groups: the EZ group, meaning they were exercising and consuming 2.5 mg/kg Zn supplement daily; the SZ group, who were supplemented without exercising; and the E group, who were exercising without being supplemented. After the period of 8 weeks, the results showed a significant increase in the erythrocyte count of the EZ group compared to the two other groups ( p < 0.001). The hemoglobin and hematocrit levels increased in the EZ group ( p < 0.05). These results revealed that the combination of exercise and Zn supplementation has a beneficial impact on the hematological parameters of athletes, which may result in enhanced performance and increased stamina [ 303 ]. Low levels of Zn in the muscles may diminish exercise endurance because it is necessary for the activity of energy metabolism enzymes [ 304 ]. Due to the influence of this enzyme on skeletal muscular exercise, lactic dehydrogenase (a Zn-containing enzyme) may facilitate the conversion of lactic acid to pyruvate [ 38 ]. This finding contradicts the commonly misinterpreted results of previous studies [ 59 , 303 ], which demonstrated that lactate accumulation does not directly cause fatigue [ 305 ].

17. Selenium

One possible approach for athletes to achieve their goals is by including selenium (Se) in their diet, as this mineral can be found in a variety of foods [ 40 ]. Selenium, when consumed in proper amounts, will help to boost an athlete’s performance, improve mental focus, and reduce inflammation, thereby contributing to overall health and fitness [ 40 , 41 , 257 ].

Selenium can be found in certain plant and animal products, and it may also be artificially added to processed foods [ 42 ]. It is advantageous for athletes due to its powerful antioxidant characteristics that boost the body’s defenses against cell damage, hence increasing endurance, strength, and overall performance [ 40 ]. Additionally, Se may increase mental focus, which improves an athlete’s ability to concentrate on tasks and stay motivated, even if the competition gets tougher [ 41 ]. It can also help to reduce levels of inflammation and support anti-inflammatory mechanisms, which may boost recovery times and minimize the risk of injuries [ 95 ]. Low levels of serum Se are associated with high serum levels of C-reactive protein (CRP), the inflammation biomarker [ 306 ] It is well addressed that Se increases glutathione peroxidase production, which prevents the effect of oxidative stress in response to exercise [ 303 ]. On the other hand, Se deficiency reduces glutathione peroxidase activity indirectly through controlling the Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) [ 257 , 307 ]. In the CHIANTI cohort study that assessed coordination performances among 1012 candidates aged 65 years or older, the authors found a reduction in neurological performance that was significantly associated with the low levels of Se [ 308 ].

Incorporating Se into an athlete’s diet may be as simple as consuming more foods that are naturally rich in Se or taking it in supplemental form. When consuming the recommended amounts, it may increase the overall health and performance of athletes [ 306 , 307 , 309 ]. Induced excessive mitochondrial oxidative stress could be caused by Se supplements overdose and may lead to serious health problems [ 273 ] marked by organelle damage and dysfunction [ 310 ]. Hence, it is important to integrate it into a balanced diet in appropriate doses rather than consuming mega doses [ 311 ]. A systematic review of oral Se supplementation of 180 µg/day or 240 µg/day ( selenium methionine ) and 200 µg/day ( Sodium Selenite ) reported a significant drop in lipid hydroperoxide levels and an increase in glutathione peroxidase (GPx) in plasma, erythrocyte, and muscle [ 306 ]. The authors concluded that the consumption of Se supplements has no impact on aerobic or anaerobic performance [ 306 ]. In addition, the study revealed that Se supplementation may inhibit Se deficiencies induced by high-volume and -intensity exercise, but it has no impact on anaerobic and aerobic athletic performance as well as creatine kinase activity, exercise training-induced adaptations, and testosterone hormone levels [ 303 , 306 ].

18. Manganese

As athletes struggle to achieve their best performance, they often look to improve their health and performance. One mineral that has been gaining recognition for its potential benefits is manganese (Mn) [ 312 ]. Mn is essential for several bodily functions, including energy production, bone formation, and enzyme activity [ 264 ]. Early studies have shown that it may help improve various aspects of athlete health and performance, but little is known about the exact benefits of Mn for athletes [ 205 , 303 ].

Manganese plays an important role in energy production, as it is involved in the breaking-down of carbohydrates, proteins, and fats needed for energy production [ 205 ]. It also helps the body to utilize energy more efficiently, which may result in improved endurance during long-term workouts and competitions [ 304 ]. Additionally, it aids in the production of important neurotransmitters, which may improve mental focus and coordination during physical activities [ 304 ]. Due to its crucial role in bone formation, several studies reported the relationship between Mn and bone health [ 43 ] It helps in the development of strong and healthy bones [ 43 ], which is crucial for athletes to prevent injury and speed up recovery time. Low serum Mn levels have been reported among osteoporotic women compared to healthy subjects [ 312 ]. Studies have also suggested that Mn helps to protect cells from damage caused by ROS, which is important during periods of strenuous exercise [ 95 , 304 ]. It is crucial for scavenging ROS in mitochondrial oxidative stress, as it involves the Mn superoxide dismutase (MnSOD) component [ 95 ].

In a clinical trial, it was found that athletes had significantly higher concentrations of basal Mn levels vs. sedentary individuals, as observed through blood and urine measurements [ 7 ]. Conversely, sedentary participants exhibited higher urine levels of Mn, which could be attributed to the possibility of iron deficiency in athletes, leading to increased Mn absorption [ 313 ]. There is limited evidence regarding Mn and athletic performance; however, athletes should be evaluated periodically for micronutrients deficiencies. Although more research needs to be conducted, the current evidence suggested that Mn may be beneficial for athletes who are looking to optimize their performance and health [ 205 , 304 ]. Adding Mn to an athlete’s diet could be useful for maximizing their performance [ 95 ].

19. Micronutrients Deficiency and Energy Deficiency’s Impact on an Athlete’s Performance

Pathways for utilizing energy are significantly influenced by vitamins and minerals [ 93 ]. A variety of physiological systems depend on micronutrients, which also have an impact on general health and athletic performance [ 23 ]. According to the widespread opinion on dietary guidelines for sports, a healthy athlete does not need to exceed RDA values if they consume an adequate number of nutrient-dense foods [ 267 ]. Unfortunately, many athletes do not meet the RDA requirements for most micronutrients [ 6 , 267 ]. Micronutrients would logically be impacted by poor macronutrient consumption [ 25 ]. It is common among many athletes who are not aware about their exercise energy demands and, on the contrary, suffer from being on a negative energy balance [ 2 ]. Negative energy balance due to increased or decreased calorie intake or a combination of both is a powerful disruptor of the endocrine milieu [ 123 ]. Additionally, it was associated with increased fatigue and mental disorders [ 14 ], reduced fertility, poor bone quality, a higher likelihood of sports injuries, endothelial dysfunction, a poor lipid profile, gastrointestinal disturbances, inflammatory processes, psychiatric conditions (such as emotional state changes/irritability), and poor athletic performance [ 93 , 108 , 154 , 314 ].

One common energy deficiency condition among athletes is the female athlete triad, characterized by disordered eating, negative energy balance, and irregular or absent menstrual cycles [ 315 ]. This condition predisposes women to menstrual dysfunction (amenorrhea) [ 316 ], diminished bone mineral density, and premature osteoporosis [ 45 ]. Each defect of the triad represents a significant medical concern, and if occurring together, the possibility of health concerns becomes even more serious and can often cause potential threats to life [ 317 ]. Medical adverse consequences associated with disordered eating involve decreased levels of glycogen in its stores, reduced lean body mass, long-term fatigue, dehydration, micronutrient deficiencies, electrolyte and acid-base imbalances, anemia, gastrointestinal diseases, parotid gland enlargement, reduced bone density, and tooth enamel erosion [ 300 ]. Osteoporosis can make adolescent female athletes prone to early bone loss and the improper formation of bone, resulting in low bone mineral density [ 318 ] and an elevated risk of stress fractures [ 319 ]. Bone mineral density lost because of amenorrhea may be totally or, at least partially, irreversible, even with the resumption of menses, calcium supplementation, and estrogen replacement therapy [ 256 , 320 ]. The dispensable role of supplementary vitamins and minerals is a concern of the Dietitians of Canada and the American College of Sports Medicine (ACSM) for ensuring adequate energy requirements are met from a varied and balanced diet with supplementations enrichment. Equally importantly, sports medicine experts may recommend the use of vitamin and mineral supplements in specific conditions such as energy intake restriction, the adoption of a plant-based diet, the presence of illness, or recovery from injuries [ 242 , 263 , 301 , 321 , 322 ]. It is worth noting that individual needs vary, and a personalized approach is crucial when making supplement recommendations.

20. Conclusions

Vitamins and minerals are crucial for an athlete’s health and performance, none more so than others. Micronutrients are essential to achieving optimal health and performance. They participate in many metabolic processes in the body, including energy production, muscle growth, and recovery. Athletes need to ensure they consume sufficient quantities of micronutrients to improve their physical activity and performance. A balanced diet that includes a variety of fruits, vegetables, whole grains, and lean proteins may help them meet their micronutrient needs. Additionally, they may benefit from taking a multivitamin supplement if they are not meeting their micronutrient requirements or suffer from malabsorption or specific deficiencies in certain vitamins. However, athletes must avoid taking micronutrient supplements without first ensuring there is a deficiency. It is important to consult with a physician or a dietitian to determine if supplementation is necessary and to obtain a proper prescription.

Abbreviations

Funding statement.

This research received no external funding.

Author Contributions

Conceptualization, H.J. and H.A.G.; Methodology, H.J.; Software, H.J.; Formal Analysis, H.J.; Writing—Original Draft Preparation, M.A.H., K.M.R., K.K.A., R.O.A., M.J., S.A. and R.A.A.; Writing—Review & Editing, H.A.G., K.T. and H.J.; Funding Acquisition, not applicable. All authors have read and agreed to the published version of the manuscript.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not Applicable.

Data Availability Statement

Conflicts of interest.

No conflict of interest.

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• Open access
• Published: 29 May 2024

High-standard predictive equations for estimating body composition using bioelectrical impedance analysis: a systematic review

• Francesco Campa   ORCID: orcid.org/0000-0002-3028-7802 1   na1 ,
• Giuseppe Coratella 2   na1 ,
• Giuseppe Cerullo 1 ,
• Zeasseska Noriega 3 ,
• Rubén Francisco 4 ,
• Davide Charrier 1 ,
• Alfredo Irurtia 3 ,
• Henry Lukaski 5 ,
• Analiza Mónica Silva 4 &
• Antonio Paoli 1  

Journal of Translational Medicine volume  22 , Article number:  515 ( 2024 ) Cite this article

Metrics details

The appropriate use of predictive equations in estimating body composition through bioelectrical impedance analysis (BIA) depends on the device used and the subject’s age, geographical ancestry, healthy status, physical activity level and sex. However, the presence of many isolated predictive equations in the literature makes the correct choice challenging, since the user may not distinguish its appropriateness. Therefore, the present systematic review aimed to classify each predictive equation in accordance with the independent parameters used. Sixty-four studies published between 1988 and 2023 were identified through a systematic search of international electronic databases. We included studies providing predictive equations derived from criterion methods, such as multi-compartment models for fat, fat-free and lean soft mass, dilution techniques for total-body water and extracellular water, total-body potassium for body cell mass, and magnetic resonance imaging or computerized tomography for skeletal muscle mass. The studies were excluded if non-criterion methods were employed or if the developed predictive equations involved mixed populations without specific codes or variables in the regression model. A total of 106 predictive equations were retrieved; 86 predictive equations were based on foot-to-hand and 20 on segmental technology, with no equations used the hand-to-hand and leg-to-leg. Classifying the subject’s characteristics, 19 were for underaged, 26 for adults, 19 for athletes, 26 for elderly and 16 for individuals with diseases, encompassing both sexes. Practitioners now have an updated list of predictive equations for assessing body composition using BIA. Researchers are encouraged to generate novel predictive equations for scenarios not covered by the current literature.

Registration code in PROSPERO : CRD42023467894.

Introduction

The determination of body composition is a common practice for evaluating health and nutritional status, as well as monitoring the effects of training or diet strategies [ 1 , 2 ]. While a simplistic approach involves assessing body composition based on body mass and its changes over time, breaking it down into different components enables a more meticulous and in-depth evaluation [ 3 , 4 ]. At the molecular level of body composition analysis [ 4 ] initial attempts to break down body mass were based on a two-component model, categorizing it into fat (FM) and fat-free mass (FFM), also known as lean mass [ 5 ]. It is worth noting that FFM is often also referred to by synonyms such as lean mass or lean body mass [ 6 ]. However, monitoring FFM alone can obscure meaningful changes in body composition since its composition comprises several components (e.g., water, protein, and minerals) not considered in the assessment [ 5 , 6 ].

To overcome the limitations of the two-component model and enhance the accuracy of body composition analysis, various multi-component models have been developed over time [ 2 ]. These models necessitate the use of one or more methods, including dual-energy X-ray absorptiometry (DXA) for bone mineral assessment, dilution techniques for total-body water, hydrostatic weighing or air displacement plethysmography for body volume, total-body potassium for body cell mass, and magnetic resonance imaging (MRI) and computed tomography for skeletal muscle or other tissues and organs [ 5 ]. For example, Wang et al. [ 3 ] presented a procedure based on a four-component model that is currently considered the state-of-art method for determining FFM and FM. Additionally, the use of multi-components models allows for the breakdown of FFM into different parts such as total body water (TBW), intra (ICW) and extracellular water (ECW), body cell mass (BCM), lean soft mass (LSM), skeletal muscle mass (SMM), and bone mass [ 7 , 8 ]. With these procedures available to researchers, predicting body mass components by assuming constant hydration of FFM (i.e., TBW/FFM = 0.73) or neglecting the potential variation in FFM and FM density [ 6 ] cannot be considered as a valid approach for assessing body composition. Indeed, several dated studies have employed coefficients such as this to derive FFM and subsequently FM based on TBW predictions, or they have relied on density assumptions to derive FFM and FM using only densitometry techniques (i.e., hydrostatic weighing or air displacement plethysmography) [ 9 , 10 , 11 ]. In particular, the practice of deriving FFM by assuming that TBW represents a constant fraction of it has led to BIA being incorrectly identified as a hydration-dependent method. Therefore, a comprehensive determination of body mass components using multi-components models enables a valid assessment of body composition in different populations, especially those with non-conventional hydration or density properties (e.g., children, athletes, or older individuals) [ 6 , 12 ].

Considering the limitations of densitometric, hydrometric, or imaging techniques for quantifying body composition due to high costs, lengthy procedures, and non-user-friendly processes, alternative methods such as bioelectrical impedance analysis (BIA) or surface anthropometry are often employed for routine assessments [ 13 , 14 , 15 , 16 ]. The theoretical basis of BIA revolves around the conductivity properties of biological tissues, quantified as bioelectrical resistance and reactance, deriving by conductor volumes (i.e., lean soft components) [ 17 ]. Bioelectrical resistance represents the opposition offered by the body to the flow of an alternating electrical current and is inversely related to the water and electrolyte content of tissues [ 17 ]. Bioelectrical reactance is related to the capacitance properties of the cell membrane and variations that can occur depending on its integrity, function, and composition [ 17 ]. Notably, these properties can be attributed to theoretical models, according to which biological tissues are traditionally conceived as electrical circuits arranged in series with each other [ 18 ]. Starting from the relationships between resistance and reactance with TBW [ 19 ], numerous BIA-based predictive equations have been developed over the years [ 20 ]. Previous studies have demonstrated that the use of different BIA technologies (i.e., hand to hand, leg to leg, foot to hand, and segmental) and sampling frequencies results in different outputs, so that these equations cannot be interchangeable between different devices [ 21 , 22 , 23 , 24 ]. Additionally, the choice of the equation should be made considering the subjects' characteristics, such as chronological and biological age, geographical provenance, sex, health status, and level of physical activity [ 25 , 26 , 27 ]. Therefore, the choice of the appropriate predictive equation is crucial to ensure the validity of the body composition estimation. A further question is that various studies including those providing reference data based on BIA do not disclose the procedures used [ 24 , 28 ]. Many of these studies merely mention the type of software employed, making it impossible to discern which formulas were used to convert raw bioelectrical parameters into components of body mass. Furthermore, such data may no longer be representative over time because companies producing such software can alter the equations without notifying users [ 29 ]. While this approach is undoubtedly quicker than a systematic and accurate selection of the most appropriate equation among those available in the literature, does not guarantee a high-standard validity.

The literature is now replete with predictive equations developed for estimating body composition using BIA. However, several limitations may question the validity of some equations. First, the use of the two-component model instead of a multi-component model approach. Second, predicting FFM and FM starting from hydration or density assumptions. Third, the development of predictive models without using criterion methods. Fourth, mixing different populations without including specific factors (e.g., age, maturity status, sex, physical activity level) as independent variables in the predictive models [ 30 ]. Therefore, the present review aimed to examine the relevant literature to extract all the predictive equations currently available, and list only those free of the aforementioned limitations. In addition, we provided a clear organization of the predictive equations based on the BIA technology, sampling frequency, and population characteristics. Such a list will help scientists and practitioners select the most appropriate predictive equations in accordance with the BIA devices and population peculiarities. Summarizing the state-of-the-art of BIA-based prediction of body composition will also be helpful to optimize the development of new predictive equations considering what is currently lacking in the literature. Obtaining accurate results would also allow for utilizing the data to evaluate other health-related parameters through estimating basal metabolism or the quantity of macronutrients based on body composition data [ 31 ]. Figure  1 depicts the premise and the problem at the basis of the present study, presenting the aims and future perspectives.

A schematization of the background and objectives set for the current study

Search strategy and eligibility criteria

The present study was carried out following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines [ 32 ]. The two independent researchers (F.C. and Z.N.) conducted systematic searches in Scopus, and PubMed on December 22th, 2023, identifying potential eligible studies without any restriction related to year of publication. A search query included combinations of at least one of the terms identifying BIA, with at least one of the terms regarding the study design, a term regarding reference techniques, and a term referring to body composition. We composed different query strings depending on the variability of the databases functioning, using the following terms: (bioelectrical impedance analysis) OR (bioimpedance) OR (BIA) AND (development) OR (new predictive equation) OR (prediction) OR (estimation) OR (Dual Energy X-ray absorptiometry) OR (dilution techniques) OR (deuterium dilution) OR (tritium dilution) OR (bromide dilution) OR (magnetic resonance imaging) OR (computerized tomography) OR (total-body potassium) OR (DXA) OR (MRI) AND (fat mass) OR (fat-free mass) OR (total body water) OR (body fluids) OR (extracellular water) OR (intracellular water) OR (body cell mass) OR (skeletal muscle mass) OR (lean soft mass) OR (lean soft tissue) OR (FM) OR (FFM) OR (TBW) OR (ECW) OR (ICW) OR (BCM) OR (SMM) OR (LSM) OR (LST) AND (three-compartment model) OR (four-compartment model) OR (3C model) OR (4C model).

The inclusion criteria were as follows:

Peer-reviewed articles that developed at least one predictive equation for estimating body mass components (i.e., FM, FFM, TBW, BCM, LSM, and SMM) using BIA.

Accessible in English in full text.

The exclusion criteria were as follows:

Research protocols, theses/dissertations, abstracts, letters to the editor, case reports, book chapters, guidelines, position papers, and unpublished works.

Articles aimed at developing predictive equations without recognized reference techniques or considering a body composition assessment based on a two-component model for FM and FFM.

Articles aimed at validating predictive equations.

Articles where the characteristics of the BIA devices (e.g., technology and sampling frequency) were not available.

Articles where predictive equations were developed by mixing different populations without including variables such as sex, maturity status, or age in the development of regression models. For example, if an equation included participants of both sexes and a sex code was included among the independent variables, the equation can be considered eligible. On the contrary, an equation including participants of both sexes without including a sex code in the predictive model cannot be considered eligible. Similarly, an equation including participants aged from 15 to 90 years old that does not require the age as independent variable was excluded from the review. Moreover, studies developing predictive equations where participants of different health status were mixed were not considered eligible.

Study selection and data processing

Based on the initial titles retrieved, duplicates were removed. After concluding the search, all records were compiled into the Endnote for Windows version X9, 2018 (Clarivate, Philadelphia, USA) software to delete all duplicates showing the same: (a) title, authors and year of publication and (b) title, authors, and journal title. The records remaining after the deletion of duplicates were exported to an Excel file for Windows version 16.75.2 (Microsoft, Washinton, EUA) organized based on essential information for screening, such as authors’ names, publication year, journal title, digital object identification (DOI), article title and abstract. Abstracts identified from the literature searches were screened for potential inclusion by two authors (F.C. and Z.N.) and a third author (G.C.) when there was a disagreement between the first two. Data extraction included information about each article, such as: authors, year, reference methods, participants’ information (gender, age, sports, diseases, geographical ancestry), bioelectrical impedance techniques and devices, predictive equations, and their characteristics. The selected studies were grouped in five categories, such as under 18 years old subjects, adults, athletes, elderly, and people with disease.

Quality assessment

Two reviewers independently assessed the quality of the included studies with the Quality Assessment of Diagnostic Accuracy Studies (Quadas-2) [ 33 ]. This scale has two dimensions (risk of bias and applicability concerns) and four domains (patient selection, index test, reference standard and flow and timing) that are scored with unclear risk, low risk, or high risk. Differences were resolved through discussions and consultations with a third researcher.

Study selection

A total of 106 BIA-based predictive equations resulted from the 64 studies included in the review. The PRISMA flow chart is shown in Fig.  2 .

PRISMA Flow chart of the studies’ selection

Risk of bias

A detailed view of the quality assessment is presented in Supplementary Table 1. Overall, the quality of studies was good. Risk of bias was high in two [ 34 , 35 ] and unclear in six [ 36 , 37 , 38 , 39 , 40 , 41 ] studies due to the low to moderate (R 2  < 80%) coefficient of determination (R 2 ) resulted from the multiple regression models. Concerns with applicability were high in 19 studies [ 37 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ] and unclear [ 41 , 50 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ] in 12 studies due to the restricted sample size.

Participants

A total of 40,626 individuals were involved in the present systematic review. Out of the total number, 18,417 participants were males and 21,414 females. Three studies involving 186 [ 70 ], 72 [ 52 ], 462 [ 71 ], and 75 [ 65 ] subjects did not specify the sex of the participants. A total of 793 males, 908 females, and 186 subjects without sex info were included in 14 studies [ 37 , 43 , 44 , 45 , 47 , 55 , 57 , 58 , 59 , 72 , 73 , 74 , 75 , 76 ] aimed to develop predictive equations for subjects aged < 18 years. A total of 14,912 males, 17,362 females, and 534 subjects without any sex designated were included in 14 studies [ 34 , 42 , 47 , 50 , 52 , 54 , 61 , 66 , 71 , 77 , 78 , 79 , 80 , 81 , 82 ] aimed to develop predictive equations for adults (from 18 to 65 years old) from the general population. A total of 885 males and 396 females were included in 11 studies [ 31 , 39 , 48 , 51 , 62 , 69 , 83 , 84 , 85 , 86 , 87 , 88 ] aimed to develop predictive equations for athletes. A total of 1469 males and N = 2111 females were included in 17 studies [ 36 , 38 , 46 , 53 , 60 , 63 , 67 , 68 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 ] aimed to develop predictive equations for elderly people. A total of 358 males, 637 females, and 75 subjects without sex designated were included in 8 studies [ 35 , 40 , 41 , 56 , 64 , 65 , 98 , 99 ] aimed to develop predictive equations for people with diseases. The number of the studies for each geographical area us depicted in Fig.  2 for each of the considered populations (Fig.  3 ).

World map with number of included studies for under 18 years old subjects ( A ), adults ( B ), athletes ( C ), elderly ( D ), and people with disease ( E )

Bioelectrical impedance-based predictive models according to gender, populations, and technologies

Figure  4 schematizes the number of equations available for each BIA technology (e.g., hand to hand, leg to leg, foot to hand, and segmental) according to sex and population.

Number of predictive equations available for each BIA technology (e.g., hand to hand, leg to leg, foot to hand, and segmental) according to sex and population

The number of the predictive equations for each estimable body mass component, according to sex and population are shown in Figs.  5 and 6 , for the foot to hand and segmental technologies, respectively.

Number of the predictive equations for each estimable body mass component, according to sex and population for the foot to hand technology. FM fat mass, FFM fat-free mass, TBW total body water, ECW extracellular water, ECW extracellular water, BCM body cell mass, LST lean soft mass, SMM skeletal muscle mass

Number of the predictive equations for each estimable body mass component, according to sex and population for the segmental technology. FM fat mass, FFM fat-free mass, TBW total body water, LST lean soft mass, SMM skeletal muscle mass

Bioelectrical impedance-based equations for under 18 years old people

Table 1 reports the characteristics of the 19 predictive equations developed in 14 studies on subjects < 18 years old from the general populations. Fifteen predictive equations from 11 studies were developed with a SF-BIA, while four predictive equations from three studies were developed with MF-BIA using bioelectrical parameters measured at 50 kHz.

Bioelectrical impedance-based equations for adults from the general population

Table 2 reports the characteristics of the 26 predictive equations developed in 14 studies on subjects from the general populations. Twenty-two predictive equations from 12 studies were developed with a SF-BIA, while four predictive equations from two studies were developed with MF-BIA using bioelectrical parameters measured at 5, 50, and 250 kHz. Only one study provided a predictive equation using BIS at a frequency of 50 kHz.

Bioelectrical impedance-based equations for athletes

Table 3 reports the characteristics of the 19 predictive equations developed in 11 studies on athletes. Fifteen predictive equations from 10 studies were developed with a SF-BIA, while four predictive equations from one study were developed with MF-BIA using bioelectrical parameters measured at 50 kHz.

Bioelectrical impedance-based equations for elderly

Table 4 reports the characteristics of the 26 predictive equations developed in 17 studies on elderly subjects. Seventeen predictive equations from 11 studies were developed with a SF-BIA, while eight predictive equations from seven studies were developed with MF-BIA using bioelectrical parameters measured at 2, 50, and 250 kHz. One study provided a predictive equations using bioelectrical parameters measured with BIS using at a frequency of 5 kHz.

Bioelectrical impedance-based equations for people with diseases

Table 5 reports the characteristics of the 16 predictive equations developed in 8 studies on subjects with diseases. Three studies presented seven predictive equations using SF-BIA, while six predictive equations from two studies were developed with MF-BIA using bioelectrical parameters measured at 50 and 100 kHz. Three studies developed three predictive equation using BIS at a frequency of 50 kHz.

The present systematic review was designed to compile a list of BIA-based predictive equations for estimating body mass components in target populations. Specifically, we included only articles that developed new predictive models and excluded experimental designs that validated existing equations, mixed different populations, or used the two-component model as a reference for developing predictive equations. This resulted in 106 predictive equations that met high-standard procedures, organized based on the four BIA technologies (i.e., hand-to-hand, leg-to-leg, foot-to-hand, and segmental), the sampling frequency (i.e., single and multi-frequency) and five population categories (i.e., under 18 years old, adults, athletes, elderly, and people with diseases). Additionally, the geographical areas of the participants were identified. The present findings provide an updated starting point for researchers to identify potential gaps in the literature and develop further predictive equations. Moreover, this updated list facilitates the easy identification of the most accurate equations for specific populations and technologies, aiding practitioners in implementing best practices.

Nineteen predictive equations developed in 14 studies on subjects under 18 years old from general populations were included. Two of these studies were conducted in the USA, where no female participants were involved [ 55 , 76 ], while the remaining 12 studies were performed in different countries around the world with both sexes included [ 37 , 43 , 44 , 45 , 57 , 58 , 59 , 72 , 73 , 74 , 75 , 100 ]. Out of the 19 equations, 12 were developed using foot to hand technology [ 37 , 55 , 58 , 59 , 72 , 73 , 75 , 76 , 100 ] and seven equations were developed using segmental technology [ 43 , 44 , 45 , 57 , 74 ]. Concerning foot-to-hand technology, four equations are suitable only for females [ 55 , 76 ], while eight are suitable for both sexes [ 37 , 58 , 59 , 72 , 73 , 75 , 100 ]. Regarding segmental technology, five are suitable for both sexes [ 43 , 44 , 45 , 57 , 74 ]. Concerning foot-to-hand technology, four equations were found for estimating FFM in females only [ 55 , 76 ] and two for both sexes [ 59 , 73 ]. As for TBW, five equations are suitable for both sexes [ 37 , 58 , 72 , 75 , 100 ]. Considering segmental technology, five equations are available for estimating FFM in both sexes [ 43 , 44 , 45 , 57 , 74 ]. All 19 equations were developed at a single frequency of 50 kHz, although four predictive equations were developed with multifrequency devices but at the frequency of 50 kHz [ 43 , 44 , 57 ].

Bioelectrical impedance-based equations for adults

Twenty-six predictive equations developed in 14 studies on adults were reviewed. Although most of the studies (n = 4) were conducted in the USA [ 34 , 42 , 54 , 82 ], the largest participant number occurred in one Chinese study [ 81 ]. The remaining studies involved European [ 50 , 52 , 71 , 77 , 101 ], Eastern Asian [ 47 , 78 ], and Australian [ 66 ] populations with a balanced number of male and female participants. Out of the 26 available equations, 22 were developed with foot to hand technology [ 34 , 42 , 47 , 50 , 52 , 54 , 61 , 66 , 71 , 77 , 78 , 102 ], and four with segmental technology Concerning foot to hand technology, 17 equations are available for both sexes [ 42 , 47 , 52 , 54 , 61 , 66 , 71 , 77 , 102 ], while one is suitable for males [ 78 ] and two are suitable for females only [ 34 , 50 ]. As for segmental technology, four equations are suitable for both sexes [ 80 , 81 ]. Regarding foot-to-hand technology, five equations are suitable for estimating FFM in males [ 47 , 52 , 66 , 71 , 78 ] and six in females [ 34 , 47 , 50 , 52 , 66 , 71 ]. Two equations are suitable for estimating TBW [ 42 , 54 ], ten for estimating LSM [ 61 , 77 ], and one for estimating SMM [ 82 ] in both sexes. Particularly, the equations predicting LSM were developed for the appendicular [ 61 , 77 ] and trunk [ 61 ] body segments. Considering segmental technology, two equations for estimating FFM [ 81 ], one equation for estimating SMM [ 80 ], and one equation for estimating LSM [ 81 ] are available for males and females. Out of the equations for predicting FFM or LSM, both estimate the appendicular mass only [ 81 ]. All these equations were developed at a single frequency of 50 kHz, with the exception of four equations [ 66 , 81 ] developed with a multifrequency devices that used bioelectrical parameters measured only at 50 kHz [ 66 ], as well as mixing frequencies sampled at 50 and 250 kHz [ 81 ].

Nineteen predictive equations developed in 11 studies on athletes were included. Four studies involved Portuguese male and female participants from different sport disciplines [ 39 , 69 , 84 , 87 ], while two studies recruited male Brazilian army cadets [ 85 ] considered as very active individuals [ 103 ] and adolescents from various sport disciplines [ 104 ]. One study was conducted on USA collegiate female athletes from different sports [ 62 ], one on Greek elite female dancers [ 51 ], and two studies on elite male soccer players in Taiwan [ 88 ] and Italy [ 31 ]. One study con considered Italian paddle players [ 48 ]. Out of the 19 available equations, 15 were developed with foot to hand technology [ 31 , 39 , 48 , 51 , 62 , 69 , 84 , 85 , 87 , 104 ], while four equations were developed using segmental technology [ 88 ]. Considering the foot to hand technology, 12 equations are suitable for male [ 31 , 39 , 48 , 69 , 84 , 85 , 87 , 104 ] and eight for female people only [ 39 , 51 , 62 , 69 , 87 , 104 ]. As for segmental technology, four equations are specific for males [ 88 ], and no equation is available for females. Regarding foot to hand technology, we found an equation for estimating FM in males [ 48 ], five equations for estimating FFM in males [ 31 , 69 , 84 , 85 , 104 ], and four in females only [ 51 , 62 , 69 , 104 ]. Moreover, we retrieved one equation for estimating TBW [ 39 ], one for estimating ECW [ 39 ] and five for estimating LSM [ 31 , 87 ], where three of them are suitable for both sexes [ 39 , 87 ], and two in male only [ 31 ]. As for segmental technology, four equations for estimating whole-body, upper-limb, lower-limb, and trunk FFM are available for males only [ 88 ]. All these equations were developed at a single frequency of 50 kHz, even those developed using a multifrequency device [ 88 ].

Twenty-six predictive equations developed in 17 studies on the elderly were included. The selected studies encompassed Central[ 36 , 38 , 49 ] and Southern American [ 46 , 67 ], European [ 53 , 63 , 89 , 90 , 91 , 93 , 95 , 97 ], and Asian [ 68 , 94 ] male and female participants. Out of the 26 available equations, 23 were developed with foot to hand technology [ 36 , 38 , 46 , 49 , 53 , 63 , 67 , 89 , 90 , 91 , 92 , 93 , 95 , 97 ], while three equations were developed using segmental technology [ 68 , 94 ]. Concerning foot-to-hand technology, three predictive equations were suitable for males [ 36 , 49 , 53 ] and four for females only [ 36 , 49 , 53 , 97 ], while thirteen equations suitable for both sexes [ 38 , 46 , 63 , 67 , 89 , 90 , 91 , 92 , 93 , 95 ]. Two different equations are available to determine FM in males and females [ 53 ], while there are two equations for assessing FFM in males [ 36 , 49 ], three in females only [ 36 , 49 , 97 ], and five suitable for both sexes [ 89 , 91 ]. There is one equation for estimating BCM [ 63 ], four equations for assessing appendicular LSM [ 46 , 67 , 92 , 93 ], and one equation for assessing SMM [ 95 ] suitable for males and females. As for the segmental technology, only the appendicular LSM is currently possible to be determined using two equations suitable for both sexes [ 68 , 94 ]. Sixteen equations were developed using single frequency devices at 50 kHz [ 36 , 38 , 46 , 49 , 53 , 63 , 67 , 89 , 90 , 91 , 97 ], while the equations developed with multifrequency devices were obtained measuring the bioelectrical parameters at 5 kHz [ 95 ], 50 kHz [ 93 , 94 ], 250 kHz [ 92 ], or 50 and 250 kHz [ 68 ].

Sixteen predictive equations developed in eight studies on people with diseases were included. The selected studies included European [ 35 , 40 , 56 , 64 , 65 , 98 ] and Asian [ 41 , 99 ] male and female participants. Out of the 16 available equations, 14 were developed with foot to hand technology [ 40 , 64 , 98 ] and eight using segmental technology [ 40 , 41 , 56 , 64 , 65 , 98 , 99 ]. Regarding the foot to hand technology, there is one equation suitable for assessing FFM in overweight and obese postmenopausal females [ 98 ], four for appendicular FM and FFM in functionally limited male and female individuals [ 40 ], four for assessing FFM in amputee males [ 41 ], one for predicting TBW in anorexic females [ 56 ], and three for appendicular LSM in frail [ 64 ], chronic kidney [ 65 ], or hemodialysis male and female subjects [ 99 ]. Seven equations were developed using single frequency devices at 50 kHz [ 35 , 40 , 98 ], while 9 equations were made with multifrequency devices involving measures obtained at 50 [ 41 , 64 , 65 , 99 ] and 100 kHz [ 56 ]. However, the use of BIA in individuals with underlying medical conditions necessitates a thorough consideration of the reliability features inherent in the measurements. This is imperative due to the heightened likelihood of fluctuations in water content, which may manifest more frequently in this cohort compared to other populations [ 105 ].

Limitations of the review and future perspectives

One limitation of the current manuscript may concern the grouping of predictive equations based on the BIA technology, since different devices using the same technology may yield different outcomes due to potential between-device inconsistencies [ 106 ], even though agreement has been observed [ 21 ]. Therefore, new comparisons between different devices of the same technology should be conducted. Other considerations could be made, not merely as limitations of the present manuscript but intrinsic to BIA. First, considering the lack of agreement between bioelectrical values obtained at different frequencies [ 21 , 107 ], the sampling frequency information has been reported for each of the included studies. In this regard, future studies should clarify the advantages of using multi-frequency devices given that most predictive equations predominantly include measures obtained at a single frequency of 50 kHz. Second, the procedures for BIA were updated in 2004 [ 15 ] and further in 2020 for athletes [ 2 ]. Therefore, inconsistencies in methodological procedures (e.g., the standardization of food and beverage intake before the assessment, electrode placement, skin cleansing) may have impacted the final outcomes for each study [ 108 ]. Third, the standard error is often reported as absolute values of body mass, and this does not take into account how much each error is related to the total body mass. For example, a standard error of 1.5 kg in a female population with a mean FFM equal to 50 kg is less precise than in men with a mean FFM equal to 80 kg. Fourth, even though some variables are not directly estimated by the BIA (e.g., FM and ICW), these can be easily derived as the difference between the body mass and the FFM (for FM) or the total water and the ECW (for ICW). Lastly, the utilization of multicomponent models to estimate body composition may be susceptible to error propagation, stemming from the use of multiple methods for reference body composition values. A procedure for identifying the most valid equation for predicting body composition is illustrated in Fig.  7 . There is reason to believe that such procedures will be considered in the development of AI-based software systems in the future.

Procedures for accurately selecting predictive equations for assessing body composition using the bioelectrical impedance analysis

Conclusions

Numerous predictive equations for quantifying body composition with BIA have been developed using high-standard procedures. However, upon categorizing these equations based on BIA technology, target population, and estimable body mass components, the overall availability of predictive equations seems limited. Notably, no predictive equations for hand to hand and leg to leg technology are included here, implying that these BIA devices predominantly employ procedures of low quality, often unknown, and lacking scrutiny, with equations typically owned by manufacturers. In contrast, there are several predictive equations available for foot to hand and segmental technology. However, the accuracy of estimating certain body components is compromised due to the absence of population-specific predictive equations. Given the necessity for reference values and BIA-based predictive equations to be population- and technology-specific, the current findings underscore the urgency of developing new predictive equations tailored to specific BIA technology, population characteristics, and body mass components. Nevertheless, the foot to hand technology stands out with the highest number of predictive equations, offering the most accurate estimation of body composition. That said, the predictive equations available so far do not cover all possible combinations of technology, population and body mass component. Hence, the present manuscript may be helpful to pinpoint what has been done so far and what is currently lacking, so to generate novel predictive equations in cases not covered by the present literature. This may help to increase the trust of the practitioners in the BIA, often doubtful about the goodness of the results provided by inaccurate equations included in the device. Practitioners now possess an updated list of predictive equations for assessing body composition.

Availability of data and materials

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

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Acknowledgements

We thank the corresponding authors of the studies included in the systematic review for providing the data where not directly available.

Open access funding provided by Università degli Studi di Padova. No funding was received to assist with the preparation of this manuscript.

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F. Campa and G. Coratella contributed equally to this work.

Authors and Affiliations

Department of Biomedical Sciences, University of Padua, Padua, Italy

Francesco Campa, Giuseppe Cerullo, Davide Charrier & Antonio Paoli

Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy

Giuseppe Coratella

NEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya (INEFC), Universitat de Barcelona (UB), 08038, Barcelona, Spain

Zeasseska Noriega & Alfredo Irurtia

Exercise and Health Laboratory, CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz-Quebrada, Portugal

Rubén Francisco & Analiza Mónica Silva

Department of Kinesiology and Public Health Education, Hyslop Sports Center, University of North Dakota, Grand Forks, USA

Henry Lukaski

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FC, GC, ZN, GC, DC, and AP: Conceptualization and Methodology; FC, GC, ZN, RF, AI, AMS, GC, and AP: Writing—Original draft preparation; HL and AP: Supervision. All authors: Writing—Reviewing and Editing.

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Campa, F., Coratella, G., Cerullo, G. et al. High-standard predictive equations for estimating body composition using bioelectrical impedance analysis: a systematic review. J Transl Med 22 , 515 (2024). https://doi.org/10.1186/s12967-024-05272-x

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Received : 23 January 2024

Accepted : 04 May 2024

Published : 29 May 2024

DOI : https://doi.org/10.1186/s12967-024-05272-x

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