Fish oil supplementation does not lower C‐reactive protein or interleukin‐6 levels in healthy adults

Randomized, double-blind, placebo-controlled, single-site trial in healthy adults aged 30–54 years (n=261). Participants were free of inflammatory conditions and had dietary EPA+DHA intake ≤300 mg/day at baseline.

Two 1000 mg fish oil capsules daily, providing 1000 mg EPA and 400 mg DHA, for 18 weeks.

1400 mg/day EPA+DHA did not reduce serum CRP or IL-6 in healthy adults over 18 weeks, nor did it affect ex vivo stimulated production of four pro-inflammatory cytokines. RBC EPA+DHA increased by 64%, confirming tissue incorporation and adherence. Conclusion: 1400 mg/day EPA+DHA does not reduce common systemic inflammation markers in healthy adults; higher-dose supplementation might affect other inflammatory measures, but feasibility for widespread primary prevention is limited.

Cytokine substudy had incomplete data with varying sample sizes; most participants had baseline CRP <2 mg/L, limiting detection of small changes; baseline CRP differed between groups; single-site study in healthy mid-life adults; findings may not generalize to high-risk or older populations; some data were imputed to handle missing values.