Fish Oil, Clearly Explained: Proven Benefits, Risks, and What the Evidence Really Says

Abstract Summary

Objective

To evaluate clinical benefits and adverse effects of fish oil in adults and summarize where supplementation is clearly indicated versus optional.

Context

EPA/DHA from marine sources influence triglyceride metabolism, platelet function, and eicosanoid signaling; these mechanisms underpin effects on cardiovascular risk, inflammation, and bleeding time. Prescription-strength products are used for hypertriglyceridemia; OTC supplements vary in purity and dose.

Methods Used

Approach

Prioritized outcomes with clinical endpoints (MI, stroke, cardiovascular death) over surrogate markers; summarized safety signals (AF, bleeding) and common nonserious adverse effects.

Data Collection

Information was drawn from large clinical trials, professional guidelines, national health databases, and peer-reviewed meta-analyses.

Researchers’ Summary of Findings

Impact on Health

For average-risk adults, routine fish oil use for prevention is not supported. For patients with elevated triglycerides on statins, prescription EPA can meaningfully reduce cardiovascular events.

Health Implications

Target supplementation to people with hypertriglyceridemia and cardiovascular risk; screen for atrial fibrillation history and anticoagulant use before prescribing high doses.

Sustainability

Whole-fish intake (especially low-mercury, sustainably sourced) is preferable to supplements. When supplementing, choose third-party-tested products with transparent sourcing.

DOI

10.1056/NEJMoa1812792; 10.1056/NEJMoa1809944; 10.1161/CIR.0000000000000482; 10.1093/ehjcvp/pvab008