case study analysis rubric

15.7 Evaluation: Presentation and Analysis of Case Study

Learning outcomes.

By the end of this section, you will be able to:

• Revise writing to follow the genre conventions of case studies.
• Evaluate the effectiveness and quality of a case study report.

Case studies follow a structure of background and context , methods , findings , and analysis . Body paragraphs should have main points and concrete details. In addition, case studies are written in formal language with precise wording and with a specific purpose and audience (generally other professionals in the field) in mind. Case studies also adhere to the conventions of the discipline’s formatting guide ( APA Documentation and Format in this study). Compare your case study with the following rubric as a final check.

Score	Critical Language Awareness	Clarity and Coherence	Rhetorical Choices
	The text always adheres to the “Editing Focus” of this chapter: words often confused, as discussed in Section 15.6. The text also shows ample evidence of the writer’s intent to consciously meet or challenge conventional expectations in rhetorically effective ways.	Paragraphs are unified under a single, clear topic. Abundant background and supporting details provide a sense of completeness. Evidence of qualitative and quantitative data collection is clear. Transitions and subheads connect ideas and sections, thus establishing coherence throughout. Applicable visuals clarify abstract ideas.	The writer clearly and consistently recognizes and works within the limits and purpose of the case study. The writer engages the audience by inviting them to contribute to the research and suggests ways for doing so. The implications, relevance, and consequences of the research are explained. The study shows mature command of language and consistent objectivity. Quotations from participant(s) are accurate and relevant.
	The text usually adheres to the “Editing Focus” of this chapter: words often confused, as discussed in Section 15.6. The text also shows some evidence of the writer’s intent to consciously meet or challenge conventional expectations in rhetorically effective ways.	Paragraphs usually are unified under a single, clear topic. Background and supporting details provide a sense of completeness. Evidence of qualitative and quantitative data collection is clear. Transitions and subheads connect ideas and sections, thus establishing coherence. Applicable visuals clarify abstract ideas.	The writer usually recognizes and works within the limits and purpose of the case study. The writer engages the audience by inviting them to contribute to the research and usually suggests ways for doing so. The implications, relevance, and consequences of the research are explained. The study shows command of language and objectivity. Quotations from participant(s) are usually accurate and relevant.
	The text generally adheres to the “Editing Focus” of this chapter: words often confused, as discussed in Section 15.6. The text also shows limited evidence of the writer’s intent to consciously meet or challenge conventional expectations in rhetorically effective ways.	Paragraphs generally are unified under a single, clear topic. Background and supporting details provide a sense of completeness. Some evidence of qualitative and quantitative data collection is clear. Some transitions and subheads connect ideas and sections, generally establishing coherence. Visuals may clarify abstract ideas or may seem irrelevant.	The writer generally recognizes and works within the limits and purpose of the case study. The writer sometimes engages the audience by inviting them to contribute to the research but may not suggest ways for doing so. The implications, relevance, and consequences of the research are explained, if not fully. The study shows some command of language and objectivity. Quotations from participant(s) are generally accurate, if not always relevant.
	The text occasionally adheres to the “Editing Focus” of this chapter: words often confused, as discussed in Section 15.6. The text also shows emerging evidence of the writer’s intent to consciously meet or challenge conventional expectations in rhetorically effective ways.	Paragraphs sometimes are unified under a single, clear topic. Background and supporting details are insufficient to provide a sense of completeness. There is little evidence of qualitative or quantitative data collection. Some transitions and subheads connect ideas and sections, but coherence may be lacking. Visuals are either missing or irrelevant.	The writer occasionally recognizes and works within the limits and purpose of the case study. The writer rarely engages the audience by inviting them to contribute to the research or suggests ways for doing so. The implications, relevance, and consequences of the research are haphazardly explained, if at all. The study shows little command of language or objectivity. Quotations from participant(s) are questionable and often irrelevant.
	The text does not adhere to the “Editing Focus” of this chapter: words often confused, as discussed in Section 15.6. The text also shows little to no evidence of the writer’s intent to consciously meet or challenge conventional expectations in rhetorically effective ways.	Paragraphs are not unified under a single, clear topic. Background and supporting details are insufficient to provide a sense of completeness. There is little evidence of qualitative or quantitative data collection. Transitions and subheads are missing or inappropriate to provide coherence. Visuals are either missing or irrelevant.	The writer does not recognize or work within the limits and purpose of the case study. The writer does not engage the audience by inviting them to contribute to the research. The implications, relevance, and consequences of the research are haphazardly explained, if at all. The study shows little command of language or objectivity. Quotations, if any, from participant(s) are questionable and often irrelevant.

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Case Study - Rubric

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Rubric example: a case study

Rubric example

	The learning plan and work plan were well-developed and supported.	The learning plan and work plan were adequately developed and supported.	The learning plan and work plan were poorly developed and supported.	The learning plan and work plan were insufficiently developed, or no posting.
	Analysis and critique of the plans were thorough and fair.	Analysis and critique of the plans were adequate.	Analysis and critique of the plans were weak.	Effort in analysis and critique was insufficient, or no comment was posted.

• Investigation and Research Discussions
• Case Study - Description
• Case Study - Example
• Steps for Building an Online Asynchronous Discussion
• Using Online Discussions to Increase Student Engagement

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Case Study rubric

• case analysis

Case Studies

Case studies (also called "case histories") are descriptions of real situations that provide a context for engineers and others to explore decision-making in the face of socio-technical issues, such as environmental, political, and ethical issues. case studies typically involve complex issues where there is no single correct answer--a student analyzing a case study may be asked to select the "best" answer given the situation 1 . a case study is not a demonstration of a valid or "best" decision or solution. on the contrary, unsuccessful or incomplete attempts at a solution are often included in the written account. 2.

The process of analyzing a case study encourages several learning tasks:

Exploring the nature of a problem and circumstances that affect a decision or solution

Learning about others' viewpoints and how they may be taken into account

Learning about one's own viewpoint

Defining one's own priorities

Making one's own decisions to solve a problem

Predicting outcomes and consequences 1

Student Learning Outcomes in Ethics

Most engineering case studies available pertain to engineering ethics. After a two year study of education in ethics sponsored by the Hastings Center, an interdisciplinary group agreed on five main outcomes for student learning in ethics:

Sensitivity to ethical issues, sometimes called "developing a moral imagination," or the awareness of the needs of others and that there is an ethical point of view;

Recognition of ethical issues or the ability to see the ethical implications of specific situations and choices;

Ability to analyze and critically evaluate ethical dilemmas, including an understanding of competing values, and the ability to scrutinize options for resolution;

Ethical responsibility, or the ability to make a decision and take action;

Tolerance for ambiguity, or the recognition that there may be no single ideal solution to ethically problematic situations 2 .

These outcomes would make an excellent list of attributes for designing a rubric for a case analysis.

Ideas for Case Study Assignments

To assign a case analysis, an instructor needs

skill in analyzing a case (and the ability to model that process for students)

skill in managing classroom discussion of a case

a case study

a specific assignment that will guide students' case analyses, and

a rubric for scoring students' case analyses.

Below are ideas for each of these five aspects of teaching with case studies. Another viewpoint is to consider how not to teach a case study .

1. Skill in analyzing a case

For many engineering instructors, analyzing cases is unfamiliar. Examining completed case analyses could help develop case analysis skills. As an exercise for building skill in analyzing cases, use the generic guidelines for case analysis assignments (#4 below) to carefully review some completed case analyses. A few completed case analyses are available:

Five example analyses of an engineering case study

Case study part 1 [Unger, S. The BART case: ethics and the employed engineer. IEEE CSIT Newsletter. September 1973 Issue 4, p 6.]

Case study part 2 [Friedlander, G. The case of the three engineers vs. BART. IEEE Spectrum. October 1974, p. 69-76.]

Case study part 3 [Friedlander, G. Bigger Bugs in BART? IEEE Spectrum . March 1973. p32,35,37.]

Case study with an example analysis

2. Skill in managing classroom discussion of a case

Managing classroom discussion of a case study requires planning.

Suggestions for using engineering cases in the classroom

Guidelines for leading classroom discussion of case studies

3. Case studies

Case studies should be complex enough and realistic enough to be challenging, yet be manageable within the time frame. It is time-consuming to create case studies, but there are a large number of engineering case studies online.

Online Case Libraries

Case Studies in Technology, Ethics, Environment, and Public Policy

Teaching Engineering Ethics: A Case Study Approach

The Online Ethics Center for Engineering and Science

Ethics Cases

The Engineering Case Library

Cases and Teaching Tips

4. A specific assignment that will guide students' case analyses

There are several types of case study assignment:

Nine approaches to using case studies for teaching

Written Case Analysis

Case Discussions

Case analyses typically include answering questions such as:

What kinds of problems are inherent in the situation?

Describe the socio-technical situation sufficiently to enable listeners (or readers) to understand the situation faced by the central character in the case.

Identify and characterize the issue or conflict central to the situation. Identify the parties involved in the situation. Describe the origins, structure, and trajectory of the conflict.

Evaluate the strengths and weaknesses of the arguments made by each party.

How would these problems affect the outcomes of the situation?

Describe the possible actions that could have been taken by the central character in the case.

Describe, for each possible action, what the potential outcomes might be for each party involved.

Describe what action was actually taken and the outcomes for each party involved.

How would you solve these problems? Why?

Describe the action you would take if you were the central character in the case. Explain why.

What should the central character in the situation do? Why?

Describe the action you think that the central character in the case should take. Explain why.

What can be learned from this case?

Delineate the lessons about ethical (or other) issues in engineering that are illuminated by this case.

This list is adapted from two online case analysis assignments by McGinn from 3 & 4 ):

5. A rubric for scoring students' case analyses

Case studies help students explore decision-making in the face of issues. Thus, for an engineering ethics case study, the outcomes that can be assessed by scoring case analyses are a) sensitivity to ethical issues, b) recognition of ethical issues, c) the ability to analyze and critically evaluate ethical dilemmas, d) the ability to make an ethical decision and take action, and e) tolerance for ambiguity. Scoring rubrics for ethics case analyses should address these outcomes, not basic knowledge of the ethical standards of the profession. Professional standards can best be assessed by a traditional graded exam in which students must demonstrate, for example, which practices are ethically acceptable versus which are in violation of ethical standards given a hypothetical scenario 5 .

Making Scoring/Grading Useful for Assessment

General principles for making scoring/grading useful for assessment ( rubrics )

Example rubrics

For a written analysis of a case study in engineering

For a written analysis of a case study in general #1

For a written analysis of a case study in general #2

For a written and oral analysis of a case study by a group

For an oral analysis of a case study by a group

For a written analysis of a case study on ethics

For a self-assessment of learning from a case study

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Graduate Case Analysis Rubric

A grading rubric for case analysis by graduate students, part of the " Genomics, Ethics and Society " course.

Your case analysis will be evaluated based on the rubric below.

Levels of Achievement
Criteria	Completely Inadequate	Slightly Inadequate	Competent	Excellent	Total Points
Identifying the Problem	Fails to identify the main conflicts and positions one could take on the issue; Does not present views fairly or treat them charitably	Some difficulties in identifying the main conflicts and positions one could take on the issue; Frequently presents different views unfairly or treats them uncharitably	Some success identifying the main conflicts and the positions one could take on the issue; Occasionally presents different views unfairly or treats them uncharitably	Accurately identifies the main conflicts and the positions one could take on the issue; Different views are presented fairly and treated charitably
Evaluate Consequences	Fails to identify what is gained or lost by all those affected by the decision	Some difficulties in identifying what is gained or lost by all those affected by the decision		Accurately identifies what is gained or lost by all those affected by the decision
Empirical Research	Fails to read, understand, and apply relevant empirical publications	Some difficulties in reading, understanding, and applying relevant empirical publications	Some success in reading, understanding, and appropriately and rigorously applying relevant empirical publications	Has read, understood, and appropriately and rigorously applied relevant empirical publications
Ethical Research	Fails to read, understand, and apply relevant ethical publications	Some difficulties in reading, understanding, and applying relevant ethical publications	Some success in reading, understanding, and appropriately and rigorously applying relevant ethical publications	Has read, understood, and appropriately and rigorously applied relevant ethical publications
Ethical Discussion	Total lack of clarity in evaluating the ethical reasoning behind and acceptability of different courses of action; Does not identify, use, or show understanding of relevant values and ethical theories to justify claims	Some lack of clarity in evaluating the ethical reasoning behind and acceptability of different courses of action; Some difficulties in identifying, using, and showing understanding of relevant values and ethical theories to justify claims	Some success in clearly evaluating the ethical reasoning behind and acceptability of different courses of action; Some success in identifying, using, and showing understanding of relevant values and ethical theories to justify claims	Clearly evaluates the ethical reasoning behind and acceptability of different courses of action; Accurately identifies, uses, and shows understanding of relevant values and ethical theories to justify claims
Creative ethical solutions	Total lack of independence and creativity in thinking about the problem and exploring alternative courses of action and possible compromises	Some lack of independence and creativity in thinking about the problem and exploring alternative courses of action and possible compromises	Mostly independent and creative in thinking about the problem and exploring alternative courses of action and possible compromises	Thinks independently about the problem, creatively exploring alternative courses of action and possible compromises
Writing Quality	Poor spelling and grammar throughout. Writing is barely coherent. No indication as to what the argument will be and how the case study analysis will be structured at the beginning of the analysis.	Some spelling and grammar errors. Does not express opinions or ideas clearly.Only vague guidance as to what the argument will be and how the case study analysis will be structured at the beginning of the analysis	Few grammatical or spelling errors. Ideas are expressed reasonably clearly. Some guidance as to what the argument will be and  how the case study analysis will be structured at the beginning of the analysis	Consistently uses correct grammar and spelling. Discussion is well organized. Expresses ideas in a clear and concise manner. Clear guidance given as to what the argument will be and how the case study analysis will be structured at the beginning of the analysis

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This material is based upon work supported by the National Science Foundation under Award No. 2055332. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

A Rubric for Evaluating Student Analyses of Business Cases

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Chiu DT , Hamlat EJ , Zhang J , Epel ES , Laraia BA. Essential Nutrients, Added Sugar Intake, and Epigenetic Age in Midlife Black and White Women : NIMHD Social Epigenomics Program . JAMA Netw Open. 2024;7(7):e2422749. doi:10.1001/jamanetworkopen.2024.22749

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Essential Nutrients, Added Sugar Intake, and Epigenetic Age in Midlife Black and White Women : NIMHD Social Epigenomics Program

• 1 Community Health Sciences Division, School of Public Health, University of California, Berkeley
• 2 Osher Center for Integrative Health, University of California, San Francisco
• 3 Department of Psychiatry and Behavioral Sciences, University of California, San Francisco
• 4 Department of Human Genetics, University of California, Los Angeles
• Original Investigation Sociodemographic and Lifestyle Factors and Epigenetic Aging in US Young Adults Kathleen Mullan Harris, PhD; Brandt Levitt, PhD; Lauren Gaydosh, PhD; Chantel Martin, PhD; Jess M. Meyer, PhD; Aura Ankita Mishra, PhD; Audrey L. Kelly, PhD; Allison E. Aiello, PhD JAMA Network Open
• Original Investigation Telehealth Parenting Program and Epigenetic Biomarkers in Children With Developmental Delay Sarah M. Merrill, PhD; Christina Hogan, MS; Anne K. Bozack, PhD; Andres Cardenas, PhD; Jonathan S. Comer, PhD; Daniel M. Bagner, PhD; April Highlander, PhD; Justin Parent, PhD JAMA Network Open
• Original Investigation Socioeconomic Status, Lifestyle, and DNA Methylation Age Alika K. Maunakea, PhD; Krit Phankitnirundorn, PhD; Rafael Peres, PhD; Christian Dye, PhD; Ruben Juarez, PhD; Catherine Walsh, PhD; Connor Slavens, BSc; S. Lani Park, PhD; Lynne R. Wilkens, DrPH; Loïc Le Marchand, MD, PhD JAMA Network Open
• Original Investigation Epigenetic Age Acceleration and Disparities in Posttraumatic Stress in Women Alicia K. Smith, PhD; Seyma Katrinli, PhD; Dawayland O. Cobb, MS; Evan G. Goff, BS; Michael Simmond, BS; Grace M. Christensen, PhD, MPH; Tyler Prusisz, BS; Sierra N. Garth, MPH; Meghan Brashear, MPH; Anke Hüls, PhD, MSc; Erika J. Wolf, PhD; Edward J. Trapido, ScD; Ariane L. Rung, PhD, MPH; Nicole R. Nugent, PhD; Edward S. Peters, DMD, SM, ScD JAMA Network Open
• Original Investigation Childhood Maltreatment and Longitudinal Epigenetic Aging Olivia D. Chang, MSW; Helen C. S. Meier, PhD; Kathryn Maguire-Jack, PhD; Pamela Davis-Kean, PhD; Colter Mitchell, PhD JAMA Network Open
• Original Investigation Familial Loss of a Loved One and Biological Aging Allison E. Aiello, PhD, MS; Aura Ankita Mishra, PhD; Chantel L. Martin, PhD; Brandt Levitt, PhD; Lauren Gaydosh, PhD; Daniel W. Belsky, PhD; Robert A. Hummer, PhD; Debra J. Umberson, PhD; Kathleen Mullan Harris, PhD JAMA Network Open
• Original Investigation Obesity and Early-Onset Breast Cancer in Black and White Women Sarabjeet Kour Sudan, PhD; Amod Sharma, PhD; Kunwar Somesh Vikramdeo, PhD; Wade Davis, BS; Sachin K. Deshmukh, PhD; Teja Poosarla, MD; Nicolette P. Holliday, MD; Pranitha Prodduturvar, MD; Cindy Nelson, BS; Karan P. Singh, PhD; Ajay P. Singh, PhD; Seema Singh, PhD JAMA Network Open
• Original Investigation Psychosocial Disadvantage During Childhood and Midlife Health Ryan L. Brown, PhD; Katie E. Alegria, PhD; Elissa Hamlat, PhD; A. Janet Tomiyama, PhD; Barbara Laraia, PhD; Eileen M. Crimmins, PhD; Terrie E. Moffitt, PhD; Elissa S. Epel, PhD JAMA Network Open
• Original Investigation Epigenetic Aging and Racialized, Economic, and Environmental Injustice Nancy Krieger, PhD; Christian Testa, BS; Jarvis T. Chen, ScD; Nykesha Johnson, MPH; Sarah Holmes Watkins, PhD; Matthew Suderman, PhD; Andrew J. Simpkin, PhD; Kate Tilling, BSc, MSc, PhD; Pamela D. Waterman, MPH; Brent A. Coull, PhD; Immaculata De Vivo, PhD; George Davey Smith, MA(Oxon), MD, BChir(Cantab), MSc(Lond); Ana V. Diez Roux, MD, PhD, MPH; Caroline Relton, PhD JAMA Network Open
• Original Investigation Prenatal Maternal Occupation and Child Epigenetic Age Acceleration Saher Daredia, MPH; Anne K. Bozack, PhD; Corinne A. Riddell, PhD; Robert Gunier, PhD; Kim G. Harley, PhD; Asa Bradman, PhD; Brenda Eskenazi, PhD; Nina Holland, PhD; Julianna Deardorff, PhD; Andres Cardenas, PhD JAMA Network Open
• Special Communication Advancing Health Disparities Science Through Social Epigenomics Research Arielle S. Gillman, PhD, MPH; Eliseo J. Pérez-Stable, MD; Rina Das, PhD JAMA Network Open

Question   Are dietary patterns, including essential nutrients and added sugar intakes, and scores of nutrient indices associated with epigenetic aging?

Findings   In this cross-sectional study of 342 Black and White women at midlife, higher added sugar intake was associated with older epigenetic age, whereas higher essential, pro-epigenetic nutrient intake and higher Alternate Mediterranean Diet (aMED) and Alternate Healthy Eating Index (AHEI)–2010 scores (reflecting dietary alignment with Mediterranean diet and chronic disease prevention guidelines, respectively) were associated with younger epigenetic age.

Meaning   The findings of this study suggest a tandem importance in both optimizing nutrient intake and reducing added sugar intake for epigenetic health.

Importance   Nutritive compounds play critical roles in DNA replication, maintenance, and repair, and also serve as antioxidant and anti-inflammatory agents. Sufficient dietary intakes support genomic stability and preserve health.

Objective   To investigate the associations of dietary patterns, including intakes of essential nutrients and added sugar, and diet quality scores of established and new nutrient indices with epigenetic age in a diverse cohort of Black and White women at midlife.

Design, Setting, and Participants   This cross-sectional study included analyses (2021-2023) of past women participants of the 1987-1997 National Heart, Lung, and Blood Institute Growth and Health Study (NGHS), which examined cardiovascular health in a community cohort of Black and White females aged between 9 and 19 years. Of these participants who were recruited between 2015 and 2019 from NGHS’s California site, 342 females had valid completed diet and epigenetic assessments. The data were analyzed from October 2021 to November 2023.

Exposure   Diet quality scores of established nutrient indices (Alternate Mediterranean Diet [aMED], Alternate Healthy Eating Index [AHEI]–2010); scores for a novel, a priori–developed Epigenetic Nutrient Index [ENI]; and mean added sugar intake amounts were derived from 3-day food records.

Main Outcomes and Measures   GrimAge2, a second-generation epigenetic clock marker, was calculated from salivary DNA. Hypotheses were formulated after data collection. Healthier diet indicators were hypothesized to be associated with younger epigenetic age.

Results   A total of 342 women composed the analytic sample (mean [SD] age, 39.2 [1.1] years; 171 [50.0%] Black and 171 [50.0%] White participants). In fully adjusted models, aMED (β, −0.41; 95% CI, −0.69 to −0.13), AHEI-2010 (β, −0.05; 95% CI, −0.08 to −0.01), and ENI (β, −0.17; 95% CI, −0.29 to −0.06) scores, and added sugar intake (β, 0.02; 95% CI, 0.01-0.04) were each significantly associated with GrimAge2 in expected directions. In combined analyses, the aforementioned results with GrimAge2 were preserved with the association estimates for aMED and added sugar intake retaining their statistical significance.

Conclusions and Relevance   In this cross-sectional study, independent associations were observed for both healthy diet and added sugar intake with epigenetic age. To our knowledge, these are among the first findings to demonstrate associations between added sugar intake and epigenetic aging using second-generation epigenetic clocks and one of the first to extend analyses to a diverse population of Black and White women at midlife. Promoting diets aligned with chronic disease prevention recommendations and replete with antioxidant or anti-inflammatory and pro-epigenetic health nutrients while emphasizing low added sugar consumption may support slower cellular aging relative to chronological age, although longitudinal analyses are needed.

Epigenetic clocks powerfully predict biological age independent of chronological age. These clocks reflect altered gene and protein expression patterns, particularly those resulting from differential DNA methylation (DNAm) at CpG (5′-C-phosphate-G-3′) sites. DNAm that accumulates over time is a testament to the toll social, behavioral, and environmental forces can have on the body. 1 - 3 These alterations often result in pathogenic processes (eg, genomic instability, systemic inflammation, and oxidative stress) characteristic of aging and chronic disease. 1 , 4 , 5 As such, myriad clocks reflecting epigenetic age have been developed for a range of age- or disease-related targets. 4 , 6 The GrimAge series contains second-generation markers of epigenetic aging that account for clinical and functional biomarkers, and is most notable for its robust associations with human mortality and morbidity risk, including time to death and comorbidity counts. 6 , 7 The recently developed version 2 of the GrimAge clock (hereafter, GrimAge2) improved on the first’s predictive abilities and confirmed its applicability for people at midlife and of different racial and ethnic backgrounds. 1 , 6

Epigenetic changes are modifiable and efforts to counter epigenetic alteration in humans have centered on lifestyle factors including diet, inspiring concepts of an “epigenetic diet” and “nutriepigenetics.” 8 , 9 So far, 2 epidemiological studies have found inverse associations between higher diet quality and slower epigenetic aging using clock measures related to mortality, including the first version of GrimAge. 7 , 10 In those studies, diet measures were reflective of healthy dietary patterns (eg, the Dietary Approaches to Stop Hypertension [DASH] diet, the Alternate Mediterranean Diet [aMED] score) emphasizing consumption of fruits, vegetables, whole grains, nuts and seeds, and legumes. 8 , 11 For example, the Mediterranean-style diet is largely plant-based with emphasis on extra virgin olive oil and seafood. This makes it replete with bioactive nutrients and phytotherapeutic compounds and low in highly processed, high fat, and nutrient-poor foods, a mixture hypothesized to be protective against low-grade chronic inflammation (“inflammaging”), oxidative stress, intracellular and extracellular waste accumulation, and disrupted intracellular signaling and protein-protein interactions. Thus, such a pattern is likely effective in preventing and reversing the epigenetic changes and pathogenic processes associated with aging, disease, and decline. 4 , 8 , 12 - 14

Dietary Reference Intakes (DRIs) are an established set of nutrient-specific reference values determined by experts that guide population intakes for adequacy and toxic effects. 15 Recent thinking, however, suggests that diets may not always adequately supply nutrients and other bioactives, particularly relative to the amounts necessary to fully condition gene expression or counteract epigenetic alterations to ensure optimal physiological metabolism. 8 Macronutrients and micronutrients play crucial roles in DNA replication, damage prevention, and repair, whereas nutrient deficiencies (and excesses) can cause genomic damage to the same degree as physical or chemical exposures. 16 Given that (1) progenome effects of some micronutrients have been observed at different and higher levels than the established DRIs and (2) determination of DRIs does not solely consider genomic stability (ie, lesser susceptibility to genomic alterations), experts have called for refining the DRIs to be better aligned for genomic health maintenance. 14 , 16 - 18 Diet quality inventories, such as those for Mediterranean-style diets, have not generally incorporated DRIs, although such considerations could clarify how food-based indices compare against requirements for related nutrients (eg, those with epigenetic properties) and refine epidemiological and intervention efforts. Accordingly, for this study, a novel nutrient index theoretically associated with epigenetic health was created and its associations with epigenetic aging were tested alongside established diet quality indices.

To date, nutriepigenetic work has mostly involved older White populations and focused on healthy dietary aspects. It is therefore important to examine the associations between nutrition and epigenetic aging in more diverse samples and to better understand what specific dietary aspects could be underlying the observed associations. Nutrients with established epigenetic action should be examined, especially considering intakes relative to amounts set forth in the DRIs and nutritional recommendations. Similarly, sugar is an established pro-inflammatory and oxidative agent that has been implicated in cancer as well as cardiometabolic diseases. 19 - 21 However, in diet quality indices often studied in the epigenetic context (eg, the aMED), sugar is noticeably unaccounted for, and it has also yet to be examined alone. Given the high consumption of sugar globally and the demographic variations within, 22 - 24 elucidating this association could motivate future dietary interventions and guidelines as well as health disparities research. This study sought to examine associations of diet with GrimAge2 in a midlife cohort comprising Black and White US women. The central hypothesis was that indicators of a healthier diet may be associated with decelerated epigenetic aging, and added sugar intake with accelerated aging.

This cross-sectional study used data from the original National Heart, Lung, and Blood Institute (NHLBI) Growth and Health Study (NGHS) (1987-1999) and its follow-up (2015-2019), which studied a cohort of Black and White females aged from 9 or 10 years into midlife (age 36-43 years), examining cardiometabolic health and related determinants. The participants were recruited based on biological female sex at age 9 or 10 years. The follow-up study re-recruited women from the California site. 25 , 26 Participants (and/or their parent[s] or guardian[s]) provided demographic data and completed online or paper surveys and new assessments. Participants received remuneration and provided informed consent. The institutional review board of the University of California, Berkeley, approved all study protocols. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology ( STROBE ) reporting guideline.

For inclusion in current analyses, the participants needed valid diet records and epigenetic data at midlife along with age and race and ethnicity information (participant self-reported); after excluding 5 women with epigenetic data quality issues, 342 individuals were included in the analytic sample. Complete case analyses were done. Among the 624 women who were followed up, the women composing the analytic sample were younger (39.2 years vs 39.9 years; P  < .001) and had greater body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) compared with women without complete diet and epigenetic data (32.5 vs 30.7; P  = .02) ( Table 1 ). No differences were otherwise observed.

Participants provided saliva samples used for DNAm analyses performed by the University of California, Los Angeles Neuroscience Genomics Core (UNGC) of the Semel Institute for Neuroscience and Human Behavior using the Infinium HumanMethylation450 BeadChip platform (Illumina, Inc). DNAm profiles were generated by Horvath’s online calculator, 27 which provided (1) estimates of epigenetic age based on GrimAge2 estimation methods; and (2) assessments of data quality (again, 5 observations did not pass quality checks). GrimAge2 uses Cox proportional hazards regression models that regress time to death (due to all-cause mortality) on DNAm-based surrogates of plasma proteins, a DNAm-based estimator of smoking pack-years, age, and female sex. It was updated from GrimAge, version 1 6 by including 2 new DNAm-based estimators of plasma proteins—high-sensitivity C-reactive protein (logCRP) and hemoglobin A 1c (log A 1c )—beyond the original 7. Linear transformation of results from these models allows GrimAge2 to be taken as an epigenetic age estimate (in years). Further information can be accessed from studies on DNA treatment and isolation and advanced analysis options for generating output files 28 or GrimAge2. 1

The participants were instructed by the NGHS study staff to self-complete a 3-day food record at follow-up for 3 nonconsecutive days. 29 Data were entered into and analyzed by the Nutrition Data System for Research (NDSR) software, version 2018 (University of Minnesota Nutrition Coordinating Center).

Mean nutrient and food intakes were calculated across valid food records for each woman based on the NDSR 2018 output. These values were used to calculate the scores of 2 overall diet quality nutrient indices (aMED and the Alternate Healthy Eating Index [AHEI]–2010) and a novel index (Epigenetic Nutrient Index [ENI]) score as described below. The aMED (Mediterranean-style diet) followed published scoring methodology 30 reflecting the degree of adherence to 9 components of an anti-inflammatory, antioxidant-rich diet. The AHEI-2010 was assessed following published scoring instructions 31 and reflects the degree of adherence to 11 dietary components associated with decreased risk for chronic disease.

This study developed a novel nutrient index (ENI) after the Mediterranean-style diet, but via a nutrient-based approach rather than a food-based one. Nutrient selection was done a priori based on antioxidant and/or anti-inflammatory capacities as well as roles in DNA maintenance and repair documented in the literature. 16 , 32 , 33 Scores can range from 0 to 24, with higher scores reflecting higher DRI adherence ( Table 2 ). 34 The internal consistency of the ENI was acceptable (Cronbach α = 0.79). The ENI also demonstrated convergent validity with r  = 0.51 ENI-aMED correlation as well as higher ENI scores in women from childhood households with higher annual incomes (13.9 vs 11.7, for ≥$40 000/y vs <$10 000/y, respectively) and parental educational attainment (14.7 vs 12.3, for ≥college graduate vs < high school graduate, respectively), corresponding to the literature. 36 Pearson correlations between the ENI and diet scores and added sugar intake were also calculated. The ENI score was moderately correlated with the AHEI-2010 score ( r  = 0.44) but not correlated with added sugar intake. The aMED and AHEI-2010 scores were highly correlated at r  = 0.73. Added sugar intake had moderate correlation with the AHEI-2010 score ( r  = −0.44) and low correlation with the aMED score ( r  = −0.28).

Added sugar intake was calculated as the mean across valid food records using NDSR output. The NDSR defines added sugar intake as the total sugar added to foods (eg, as syrups and sugars) during food preparation and commercial food processing. Monosaccharides and disaccharides naturally occurring in foods are not included. 35

To maximize internal validity and minimize confounding, several covariates were included. Age and sample batch were controlled for as well as naive CD8 and CD8pCD28nCD45Ran memory and effector T-cell counts, thus accounting for normal cell count variation. To control for baseline factors and their potential influence on diet and epigenetic age over time, the following parameters assessed at age 9 or 10 years (mostly parent or caregiver reported) were further adjusted for annual household income, highest parental educational attainment, number of parents in household, and number of siblings. Additionally, self-reported race (Black or White) as well as the current health and lifestyle factors of self-reported chronic conditions (yes to any of the following ever: cancer, diabetes [including gestational, prediabetes], hypertension, or hypercholesterolemia) or medication use (currently yes for any of the following conditions: diabetes, hypertension, hypercholesterolemia, or thyroid), BMI (measured), having ever smoked (yes or no), and mean daily total energy intake (as higher diet quality scores might result from higher energy intake) 37 were also included.

Descriptive analyses provided summary statistics. Linear regression models estimated unadjusted and adjusted cross-sectional associations between each of the 4 dietary exposures with GrimAge2. Per expert recommendations, unadjusted models controlled for women’s current age, sample batch, and both naive CD8 and CD8pCD28nCD45Ran memory and effector T-cell counts. Adjusted models controlled for those variables in addition to relevant sociodemographic and health behavior–related covariates already listed. To examine the association between healthy diet measures together with added sugar intake and GrimAge2, aMED, AHEI-2010, and ENI scores were each separately put into the same fully adjusted multivariable linear regression model. The threshold for statistical significance was 2-tailed (α = .05) and all statistical analyses were conducted from October 2021 to November 2023 with Stata15 SE, version 15.1 (StataCorp LLC).

The analytic sample of this study comprised 342 women (mean [SD] age at follow-up, 39.2 [1.1] years; 171 [50.0%] Black and 171 [50.0%] White participants; mean [SD] BMI, 32.5 [10.0]; 150 [43.9%] ever smokers; 164 [48.0%] ever diagnosed with a chronic condition; and 58 [17.0%] currently taking medication) ( Table 1 ). The participants were well distributed across socioeconomic status categories at baseline (9-10 years old). The participants presented with low to moderate levels of diet quality; the mean (SD) scores were 3.9 (1.9) (possible range, 0-9) on the anti-inflammatory, antioxidant Mediterranean-style pattern (aMED); 55.4 (14.7) (possible range, 0-110) on the AHEI-2010 for chronic disease risk; and 13.5 (5.0) (possible range, 0-24) on the ENI for intakes of epigenetic-relevant nutrients relative to DRIs. The participants also reported mean (SD) daily added sugar intake of 61.5 (44.6) g, although the score range was large (2.7-316.5 g).

Table 3 provides the overall unadjusted and adjusted associations between each dietary exposure of interest and GrimAge2 resulting from multivariable linear regression models. In both unadjusted and adjusted models, all dietary exposures were statistically and significantly associated with GrimAge2 in the hypothesized, anticipated direction. In adjusted models, the associations observed for each dietary exposure were slightly attenuated. Each unit increase in the scores was associated with year changes in GrimAge2, as follows: aMED (β, −0.41; 95% CI, −0.69 to −0.13), AHEI-2010 (β, −0.05; 95% CI, −0.08 to −0.01), and ENI (β, −0.17; 95% CI, −0.29 to −0.06), indicating that healthier diets were associated with decelerated epigenetic aging. Each gram increase in added sugar intake was associated with a 0.02 (95% CI, 0.01 to 0.04) increase in GrimAge2, reflecting accelerated epigenetic aging.

Table 4 illustrates the associations of healthy diet measures (aMED, AHEI-2010, and ENI scores) and added sugar intake with epigenetic aging and gives the adjusted results for each healthy diet measure and added sugar intake with GrimAge2 in the context of each other. In all instances, healthier diet measures and added sugar intake appeared to maintain their independent associations with GrimAge2 in the expected directions. Associations were statistically significant for added sugar intake in all models as well as for aMED scores; 95% CIs were more imprecise for AHEI-2010 and ENI scores.

The findings of this cross-sectional study are among the first, to our knowledge, to demonstrate the association of added sugar intake with an epigenetic clock. Further, to our knowledge, it is the first study to examine the associations of diet with GrimAge2 and extend the applicability of such results to a cohort of Black and White women at midlife. As hypothesized, measures of healthy dietary patterns (aMED, AHEI-2010 scores), and high intakes of nutrients theoretically related to epigenetics (ENI) were associated with younger epigenetic age, while a higher intake of added sugar was associated with older epigenetic age. Additionally, this study examined indicators of healthy and less healthy diets in the same model, allowing simultaneous evaluation of each in the presence of the other. Although the magnitudes of associations were diminished and some 95% CIs became wider, their statistical significance generally persisted, supporting the existence of independent epigenetic associations of both healthy and less healthy diet measures. This approach is informative, as dietary components are often examined singularly or in indices, which can lead to erroneous conclusions if key contextual dietary components are not accounted for or are obscured. From these findings, even in healthy dietary contexts, added sugar still has detrimental associations with epigenetic age. Similarly, despite higher added sugar intake, healthier dietary intakes appear to remain generally associated with younger epigenetic age.

The number of published nutriepigenetic studies, particularly on examining second-generation epigenetic clock markers, is still relatively small. However, the results of the present study are consistent with the literature. Two other studies 7 , 10 have examined GrimAge1-associated outcomes and found higher diet quality scores, including the DASH and aMED, were associated with slower epigenetic aging. However, those studies were limited to older (>50 years) and White populations, limiting their demographic generalizability. Analyses of epigenetic aging and added sugar intake are new, but findings are consistent with the larger body of epidemiological work that has drawn connections between added sugar intake and cardiometabolic disease, 19 , 20 perhaps suggesting a potential mechanism underlying such observations. Granted, point and 95% CI estimates for the added sugar–GrimAge2 associations were close to zero, suggesting a smaller role for added sugar compared with healthy dietary measures; however, more studies are needed. Nevertheless, their statistical significance was persistent.

Nutrient-based inventories can provide epidemiological contributions for genomic health studies. The idea of epigenetically critical nutrients is important for 2 reasons. First, it supports the notion that epigenetic nutrient intakes above DRI levels could boost epigenetic preservation and potentially motivate updates to nutritional guidelines, an outcome advocated for by nutriepigenetic experts. 16 - 18 In the novel ENI constructed for the present study, points were awarded based on comparisons of average daily intakes with: (1) estimated average requirements, or the requirement considered adequate for half of the healthy individuals in a population, and (2) recommended dietary allowances or adequate intakes, or where 97% to 98% or essentially all of a population’s healthy individuals’ requirements for a nutrient are met. 15 Future iterations could test varying ENI scoring parameters relative to DRIs for epigenetic benefit. Second, taking a nutrient approach suggests that any dietary pattern rich in vitamins, minerals, and other bioactives could be useful for preserving epigenetic health. This is helpful because dietary patterns are socioculturally influenced, but a nutrient focus rather than a focus on foods could help bridge cultures, class, and geography. 9 The Okinawan diet, for example, is nutritionally similar to the Mediterranean-style diet but more aligned to Asian tastes. 38 In general, the sociodemographic determinants of diet should not be discounted. Across the US population, for instance, it is known that overall diet quality is mediocre and relatively low while added sugar intake is considerably high, as also observed in the sample of the present study. However, specific nutrient intakes will vary based on the particulars of dietary patterns. 22 , 36 As dietetics and medicine progresses into the era of personalized nutrition and personalized medicine, the role of social factors including diet will be important to consider in epigenetic studies and could figure prominently in work on health disparities.

Strengths of this study are its inclusion of a diverse group of women as well as use of robust measures of diet and DNAm. It was also possible to control for several potential sociodemographic confounders.

This study also has limitations. As a cross-sectional study, it is not possible to infer causality without temporality, and therefore longitudinal studies are needed. Additionally, diet was self-reported via 3-day food records, which may lead to underestimates and overestimates of intakes depending on the nutrient. Therefore, augmenting dietary assessment with food frequency questionnaires and/or biomarkers could be helpful. 39 Also, other nutrients with pro-epigenetic properties were not included in the current ENI. Still, the Cronbach α for this first ENI version was acceptable at 0.79 and it demonstrated good convergent validity with customary socioeconomic and demographic characteristics. The tolerable upper intake levels of the DRIs were not considered in constructing the ENI. Future work should assess the prevalence of intakes beyond upper limits to assess whether toxicity could be a concern.

To our knowledge, the findings of this cross-sectional study are among the first to find associations between indicators of healthy diet as well as added sugar intake and second-generation epigenetic aging markers and one of the first to include a cohort of Black women. Higher diet quality and higher consumption of antioxidants or anti-inflammatory nutrients were associated with younger epigenetic age, whereas higher consumption of added sugar was associated with older epigenetic age. Promotion of healthy diets aligned with chronic disease prevention and decreased added sugar consumption may support slower cellular aging relative to chronological age, although longitudinal analyses are needed.

Accepted for Publication: April 29, 2024.

Published: July 29, 2024. doi:10.1001/jamanetworkopen.2024.22749

Open Access: This is an open access article distributed under the terms of the CC-BY License . © 2024 Chiu DT et al. JAMA Network Open .

Corresponding Author: Dorothy T. Chiu, PhD, Osher Center for Integrative Health, University of California, San Francisco, 1545 Divisadero St, #301D, San Francisco, CA 94115 ( [email protected] ); Barbara A. Laraia, PhD, MPH, RD, Community Health Sciences Division, School of Public Health, University of California, Berkeley, 2121 Berkeley Way, Berkeley, CA 94720 ( [email protected] ).

Author Contributions: Drs Chiu and Laraia had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Drs Epel and Laraia share co–senior authorship on this article.

Concept and design: Chiu, Hamlat, Epel, Laraia.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Chiu, Hamlat, Laraia.

Critical review of the manuscript for important intellectual content: Hamlat, Zhang, Epel, Laraia.

Statistical analysis: Chiu, Hamlat, Zhang.

Obtained funding: Epel, Laraia.

Administrative, technical, or material support: Chiu, Laraia.

Supervision: Epel, Laraia.

Conflict of Interest Disclosures: Dr Chiu reported receiving support from grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD); the National Heart, Lung, and Blood Institute (NHLBI); the National Institute on Aging (NIA); and the National Center for Complementary and Integrative Health (NCCIH) during the conduct of the study. Dr Hamlat reported receiving grants from the National Institutes of Health (NIH) during the conduct of the study. Dr Laraia reported receiving grants from NIH NICHD during the conduct of the study. No other disclosures were reported.

Funding/Support: The research reported in this publication was supported by grant R01HD073568 from the Eunice Kennedy Shriver NICHD (Drs Laraia and Epel, principal investigators [PIs]); grant R56HL141878 from the NHLBI; and grants R56AG059677 and R01AG059677 from the NIA (both for Drs Epel and Laraia, PIs). The participation of Dr Chiu was supported by the University of California, San Francisco Osher Center research training fellowship program under grant T32AT003997 from NCCIH.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Data Sharing Statement: See the Supplement .

Additional Contributions: We recognize the past and present NHLBI Growth and Health Study (NGHS) staff for their talents and dedication, without which the study and these analyses would not have been possible. We also thank the Nutrition Policy Institute for providing consultation and support with historical study data. Additionally, we express immense gratitude to Ake T. Lu, PhD, and Steve Horvath, PhD, now of Altos Labs, for their epigenetic clock expertise and consultation. Neither was financially compensated for their contributions beyond their usual salary. Of note, we thank the NGHS participants for their time and efforts over the years.

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