Our Study at a Glance

Essential elements of our study include:

  • Isolating and examining the effects of DHA and EPA on human health and exercise performance
  • 16-week study duration
  • Supplementing with 4 grams per day of either DHA, EPA, or placebo
    • To learn more about DHA and EPA, please visit About Omega-3s or the sections below
  • Three lab visits for each participant (week 1, week 8, week 16), each lasting ≈ 3 hours:
    • Measuring body composition
    • Measuring resting metabolic rate (RMR) and heart rate variability (HRV)
    • Collecting blood and urine for analysis
    • Completing a treadmill exercise procedure
    • Measuring VO2 peak and respiratory exchange ratio (RER)
  • Dietary and exercise tracking (daily)
  • Maintaining current exercise activities (average ≈ 3-4 hours per week)

Detailed descriptions of our focus, innovations, and the significance and broader impact of our study are included in the sections below.

Study focus

Omega-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFA) have been a subject of research inquiry since the early 1970s thanks to the seminal work of Bang et al. who observed a correlation between high levels of ω-3 fatty acids and low incidence of cardiovascular disease (CVD) in a population of Greenlandic Eskimos [1,2]. ω-3 LCPUFA are commonly obtained via the diet by consuming oily fish such as salmon and may also be obtained via oral supplementation (soft gels). Discovery of their pleiotropic effects on human health (e.g., cardioprotective [3-5], triglyceride-lowering [6-8], and anti-inflammatory [9-11]) have driven significant medical and public interest in ω-3 LCPUFA. Studies over the past several decades have identified docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) as the ω-3 LCPUFA that are primarily responsible for these effects [12-16]. The majority of research to date has examined the effects of DHA and EPA in combination rather than isolating their singular impact (this is due to the fact that purified, isolated DHA was not available until 1990 [17] and because primary food sources supplying these ω-3 fatty acids are comprised of blends of EPA and DHA). The importance of DHA to human physiology would be difficult to overstate: DHA is an element of every cell in the human body, modifies cell membrane properties, is found in higher concentrations than EPA in areas such as the brain and cardiac tissue, and is differentially conserved relative to EPA [18-21]. Due to the undisputed positive effects of DHA on the body, its unique role in human biology, and a relative dearth of research exploring the independent impacts of DHA and EPA, further investigation of this ω-3 LCPUFA is needed. Our study is designed to leverage and add to the existing body of knowledge by comprehensively investigating the independent effects of DHA and EPA on inflammation; oxidative stress; metabolic health; resting, exercising, and post-exercise metabolic and subjective responses; body composition; and resting and exercising heart rate activity.


Our study design is exceptionally comprehensive and contains a combination of unique and additive elements relative to prior studies in this area. These elements include: [i] subject population, [ii] study duration (16 weeks), [iii] the isolation of DHA relative to EPA, [iv] supplement dose (4 g/d), [v] supplement formulation, [vi] dietary intake tracking, [vii] use of a highly-validated, rapid, and cost-effective technique to measure blood lipid levels, and [viii] the breadth of data collected for significant cellular biomarkers.

  • Subject population. The focus of our study is adults ages 25-50 who are healthy and physically active. Based on our literature review to date, this is an understudied population.
  • Subject duration. Owing to DHA’s location on the inner phospholipid bilayer and its membrane altering qualities, it is critical for a study to be of sufficient duration for incorporation into the cell membrane to occur. Based on numerous studies, the validation of erythrocytes as a biomarker for cellular incorporation of DHA, and the life span of an erythrocyte, prior studies in this area (many < 12 weeks) may not have been of sufficient duration leading to erroneous conclusions and misinterpretation of study findings [22-26].
  • Isolation of DHA relative to EPA. Based on our literature review, there are fewer than 90 human studies since 2000 that have attempted to isolate the effects of DHA relative to EPA [27]. Of particular note is that [i] these studies have comprised a wide variety of populations (ranging from toddlers to older adults) and focal points (e.g., heart, exercise, brain, visual system, and other medical aspects) [27] and [ii] the vast majority were completed before the publication of best practices covering ω-3 studies [26].
  • Supplement dose. A growing body of evidence is leading to the conclusion that long-term supplementation (measured in months) in conjunction with daily threshold dosages are required to elicit positive physiological effects [28]. The dosages used to study the effects of ω-3 LCPUFA have varied significantly, with the majority using <1.5 g/d (blended EPA-DHA, with EPA > DHA). We note that dosages in DHA-specific studies have often been < 1.0 g/d [27].
  • Supplement formulation. ω-3 LCPUFA may be ingested in three primary forms: as free acids, triacylglycerols, or ethyl esters. Each form is absorbed in the human body at a different rate, and the relative bioavailability of each may have a profound effect on dose-response and physiological effect [29-31]. The most common and cost-effective formulation of EPA and DHA supplementation is ethyl ester. We intend to perform our study using superior formulations of EPA and DHA (high bioavailability).
  • Dietary intake tracking. Our study will be the first in this area to use a superior platform (Cronometer) for dietary intake tracking. Prior studies have relied on the sporadic use of food frequency questionnaires. Given the inherent inaccuracy associated with periodic food recall [32], as well as the presence of ω-3 LCPUFA in the food supply, it is imperative to control for dietary intake. We note that the Cronometer platform is curated for accuracy and reliability and has been used previously in a peer-reviewed, published study [33].
  • Measuring blood lipid levels. We are the beneficiary of technological advances over the past two decades relating to the reliable, rapid, and cost-effective measurement of human blood lipid profiles. The process of using a capillary draw to place blood drops on a piece of treated cardstock that is subsequently analyzed has been highly validated [34-46].
  • Breadth of data collected. We are collecting a broad range of basic and applied data that will leverage and extend the work of previous studies. Specifically, we seek to investigate the effects of DHA and EPA, independently, on [i] cardiometabolic health markers (e.g., metabolic panel, lipid panel, body composition, resting energy expenditure); [ii] inflammation and oxidative metabolism (e.g., oxidative stress); [iii] mitochondrial function; [iv] heart rate activity (e.g., heart rate variability (HRV), resting heart rate, and heart rate recovery); [v] exercise economy (e.g., oxygen consumption, lactate production and clearance, and exercise energy expenditure); and [vi] rating of perceived exertion (RPE).

Significance and Broader Impact

Societal changes and technological advances over the past 150 years has resulted in a Western diet that is now both deficient in ω-3 and excessive in omega-6 (ω-6) fatty acids [47,48]. Excessive amounts of ω-6 fatty acids and a high ω-6 to ω-3 ratio promote the pathogenesis of several diseases, including cardiovascular disease (CVD), cancer, and inflammatory and autoimmune diseases [49]. For comparison, humans evolved on a diet with a ratio of ω-6 to ω-3 ratio of ≈ 1:1, whereas today, that ratio often exceeds 20:1 [15,49]. Virtually all diseases, including diabetes, obesity, CVD, and neurodegenerative diseases manifest symptoms of inflammation [15]. Collectively these diseases account for the vast majority of major human pathologies and death. DHA is a component of all mammalian cell membranes [50] and possesses unique cellular properties [18], and the consumption of DHA reduces inflammation. Based on the preceding facts, it would, therefore, be difficult to overstate the implications of ongoing research into the benefits of ω-3 LCPUFA.

The broader impact of this study, and of ω-3 fatty acids in general, is to leverage the efficacy, cost-effectiveness, safety, and availability of EPA and DHA. Further exploration into the effects of EPA and DHA (e.g., mitochondrial function, oxidative stress, inflammation, body composition, metabolism at rest and during exercise) that may improve health profiles of the general adult population are likely to yield significant quality of life improvements and economic value to society by lowering the costs associated with significant morbidities, such as CVD, type 2 diabetes, and inflammatory disorders and diseases.

This study is a reflection of our efforts to leverage connections between disciplines, develop and research novel hypotheses, and–ultimately–add to the body of knowledge in this critical area. Our study, as designed, will position the research team to author and submit multiple articles for publication in high-impact, peer-reviewed journals and collect data that can be leveraged into several external grant opportunities. Benefits from the study will accrue to KSU (both institutionally and for the student body, via extensive research assistant involvement at both the undergraduate and graduate levels) and society at large (e.g., further elucidation of the physiological benefits of ω-3 LCPUFA supplementation).


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