Joint effects of one year of marine omega-3 fatty acid supplementation and participant dietary fish intake upon circulating lipid mediators of inflammation resolution in a randomized controlled trial.

Objectives: We assessed the joint effects of omega (n)-3 fatty acid supplementation and dietary fish intake on systemic lipid mediators of inflammation among adults.

Methods: Within VITAL, a double-blind randomized controlled trial, adults were randomized to ω-3 fatty acids (460 mg EPA + 380 mg DHA/d) or placebo. We selected participants who reported low (<1 serving/mo) baseline dietary fish intake and matched them by age, sex, race, and trial arm to participants with self-reported highest fish intake (≥3.9 servings/wk). Baseline and 1-y plasma samples were tested for 9 ω-3 fatty acid-derived lipid mediators. Multivariable linear models assessed lipid mediator changes and joint effects of ω-3 fatty acid supplementation and dietary fish intake.

Results: Forty-eight participants with low baseline fish intake were matched to 48 with high fish intake. Mean age was 64.6 (±7.26), 50% were female, and 85% non-Hispanic white. One-year lipid mediator changes in expected directions were observed in those receiving ω-3 fatty acids versus placebo: reductions in proinflammatory mediators, PGD2, 5-HETE, and 12-HETE; increases in proresolving mediators, EPA and DHA. Larger 1-y lipid biomarker changes were seen in those with low baseline fish intake randomized to active ω-3 fatty acids for DHA, EPA, PGD2, Resolvin D1, and Resolvin D4 were observed, although no significant multiplicative interactions were detected.

Discussion: Beneficial changes in circulating proresolving and proinflammatory mediators were found with 1-y of ω-3 fatty acid supplementation versus placebo for all participants, with a trend toward larger effects among those with low baseline fish intake, although interactions were not significant.