Association of reported fish intake and supplementation status with the omega-3 index

Prostaglandins Leukot Essent Fatty Acids. 2019 Mar;142:4-10. doi: 10.1016/j.plefa.2019.01.002. Epub 2019 Jan 11.


Background: An Omega-3 Index (O3I; EPA+DHA as a % of erythrocyte total fatty acids) in the desirable range (8%-12%) has been associated with improved heart and brain health.

Objective: To determine the combination of fish intake and supplement use that is associated with an O3I of >8%.

Design: Two cross-sectional studies comparing the O3I to EPA+DHA/fish intake.

Participants/setting: The first study included 28 individuals and assessed their fish and EPA+DHA intake using both a validated triple-pass 24-hr recall dietary survey and a single fish-intake question. The second study used de-identified data from 3,458 adults (84% from US) who self-tested their O3I and answered questions about their fish intake and supplement use.

Statistical analyses performed: Study 1, chi-squared, one-way ANOVA, and Pearson correlations were computed. In Study 2, multi-variable regression models were used to predict O3I levels from reported fish/supplement intakes.

Results: The mean ± SD O3I was 4.87 ± 1.32%, and 5.99 ± 2.29% in the first and second studies, respectively. Both studies showed that for every increase in fish intake category the O3I increased by 0.50-0.65% (p < 0.0001). In the second study, about half of the population was taking omega-3 supplements, 32% reported no fish intake and 17% reported eating fish >2 times per week. Taking an EPA+DHA supplement increased the O3I by 2.2% (p < 0.0001). The odds of having an O3I of ≥8% were 44% in the highest intake group (≥3 servings/week and supplementation) and 2% in the lowest intake group (no fish intake or supplementation); and in those consuming 2 fish meals per week but not taking supplements (as per recommendations), 10%.

Conclusions: Current AHA recommendations are unlikely to produce a desirable O3I. Consuming at least 3 fish servings per week plus taking an EPA+DHA supplement markedly increases the likelihood of achieving this target level.

Keywords: Dietary records; Dietary supplements; Docosahexaenoic acid; Eicosapentaenoic acid; Fish; Food frequency questionnaire; Omega-3 fatty acids; Omega-3 index.

MeSH terms

  • Adult
  • Aged
  • Biomarkers / blood
  • Cohort Studies
  • Cross-Sectional Studies
  • Dietary Supplements*
  • Docosahexaenoic Acids / blood*
  • Dried Blood Spot Testing
  • Eating / physiology*
  • Eicosapentaenoic Acid / blood*
  • Erythrocytes / chemistry
  • Female
  • Fish Products*
  • Humans
  • Male
  • Middle Aged
  • Self Report
  • Young Adult


  • Biomarkers
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid