Cross-sectional study of the combined associations of dietary and supplemental eicosapentaenoic acid + docosahexaenoic acid on Omega-3 Index

Studies have linked an Omega-3 Index (O3I), which measures eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) in red blood cell membranes, of ≥8% with improved health. Previous studies found that the American Heart Association (AHA) recommendation of 1-2 seafood meals per week does not achieve an O3I ≥8% even with an EPA + DHA supplement; however, these studies did not assess the frequency or amount of supplemental intake. Among participants in a predominantly US and Canadian cohort with high nutrient supplement use, we hypothesized that those adhering to the AHA guidelines would not have an average O3I ≥8% but that those taking a daily supplement would. Fish consumption and EPA + DHA supplement use were reported by 1795 participants; 985 also completed a blood spot test for O3I. A majority (71%) consumed <2 servings per week of fatty fish, and 61% took an EPA + DHA supplement. The amount of EPA + DHA for 1 serving (based on the product label) significantly differed among the >400 supplement products (50-3570 mg). O3I was ≥8.0% in 19% of participants. Among non-supplement takers, 3% of those consuming 1 fish serving per week and 17% consuming ≥2 achieved an O3I ≥8.0%. Among those consuming ≥2 fish servings per week, only those also taking an average of 1100 mg/d of supplemental EPA + DHA had a median O3I ≥8.0%. Based on the relationship between supplemental EPA + DHA intake and O3I for non-fish eaters (R² = 0.40, P < .0001), an average of ~1300 mg/d of EPA + DHA achieved an O3I of 8.0%. This study suggests that following the AHA guidelines does not produce an O3I ≥8% nor does taking 1 serving per day of most omega-3 supplements.