Omega-3s

What the evidence says

VITAL randomized 25,871 generally healthy older adults to 1 g per day of marine omega-3s or placebo for a median of 5.3 years. Supplementation did not significantly reduce major cardiovascular events, cancer, or all-cause mortality, although total myocardial infarction was lower as a secondary outcome.^[1]

A Cochrane review of 86 trials with 162,796 participants concluded that increasing long-chain omega-3 intake has little or no effect on all-cause mortality, overall cardiovascular events, or stroke, with at most small reductions in some coronary outcomes.^[2]

A separate 38-trial meta-analysis found modest reductions in cardiovascular mortality, nonfatal heart attack, and major cardiovascular events, with larger estimates in EPA-only trials. It also found more atrial fibrillation, illustrating that a small average benefit is not risk free.^[3]

Prescription results are not interchangeable with ordinary fish oil. REDUCE-IT found fewer cardiovascular events with 4 g per day of purified EPA in statin-treated high-risk patients with elevated triglycerides, whereas STRENGTH found no benefit from 4 g per day of an EPA-DHA formulation and observed more new atrial fibrillation.^[4][5]

NIH distinguishes seafood, dietary supplements, and prescription omega-3 drugs. Prescription products reliably lower very high triglycerides; that does not establish routine over-the-counter fish oil as a general heart-health, cognition, or longevity intervention.^[6]