Omega-3 and Aging: What the Best Trials Actually Show

EPA! DHA! The most-studied supplement habit in aging — and the trial record will not sit still. In 777 older adults, omega-3 slowed three of four DNA-methylation aging clocks. In 25,871 healthy adults, it did nothing for major cardiovascular events. Zip.

The honest summary: real but uneven — encouraging signals on biological-aging measures, a cardiovascular record swinging from positive at high-dose purified EPA to flatly null, depending on the trial.

A small signal on biological aging

The most relevant longevity finding comes from a 2025 analysis of the DO-HEALTH trial, published in Nature Aging. In 777 older adults, researchers tested vitamin D (2,000 IU/day), omega-3 (1 g/day), and a home exercise program against four next-generation DNA-methylation "clocks" of biological aging over three years. Omega-3 alone slowed three of the clocks (PhenoAge, GrimAge2, and DunedinPACE), and all three interventions together had an additive benefit on PhenoAge. The effects were small: roughly 0.16 to 0.32 standardized units, equivalent to about 2.9 to 3.8 months of slower aging. Importantly, this was a post-hoc analysis of methylation markers, not a test of whether people actually lived longer or healthier, so it is best read as a promising mechanistic hint rather than proof.

The cardiovascular picture is genuinely mixed

Here the trials disagree, and that disagreement is the real story. In the VITAL trial (New England Journal of Medicine, 2018), 25,871 generally healthy adults took 1 g/day of marine omega-3 or placebo for a median of 5.3 years. The main result was null: major cardiovascular events occurred in 386 omega-3 participants versus 419 on placebo (hazard ratio 0.92, 95% CI 0.80 to 1.06), and there was no reduction in cancer. A secondary endpoint, total heart attacks, was lower (HR 0.72), but a single positive secondary outcome in an otherwise null trial should be treated cautiously.

REDUCE-IT (NEJM, 2018) looked very different. Using a high dose (4 g/day) of purified EPA as icosapent ethyl in 8,179 statin-treated patients with elevated triglycerides, it found a clear benefit: the primary composite endpoint dropped from 22.0% to 17.2% (HR 0.75). But the comparison was not clean, and STRENGTH (a secondary analysis in JAMA Cardiology, 2021, of 13,078 high-risk patients) used a different omega-3 formulation against a corn-oil comparator and found neither benefit nor harm, even at the highest achieved blood levels of EPA and DHA (HRs around 0.98 to 1.02). One ongoing debate is whether REDUCE-IT's mineral-oil placebo made the drug look better by comparison.

Side effects and the honest bottom line

High-dose EPA is not free: REDUCE-IT found more hospitalizations for atrial fibrillation (3.1% vs 2.1%). For most people eating little fish, modest omega-3 intake is reasonable and low-risk, but it is not a proven longevity drug. The biological-aging data are early and preliminary, and the hard-outcome cardiovascular data are inconsistent. Educational, not medical advice.