Omega-3 Slowed Biological Aging in the DO-HEALTH Trial

By Longevity Lab · Published: August 11, 2026

Based on peer-reviewed research — full source list at the end of this article. This is educational information, not medical advice.

In the DO-HEALTH trial, 1 gram of omega-3 a day slowed biological aging measured by epigenetic clocks in 777 older adults followed for 3 years. The results, published in Nature Aging, make DO-HEALTH one of the first randomized controlled trials (RCTs) to show a supplement changing the measured pace of aging in people, rather than only improving a lab value.

What the epigenetic clocks measure

Biological age is not the number on your passport. It is an estimate of how worn down the body actually is. One way to measure it is with epigenetic clocks, which read chemical tags on DNA (DNA methylation) and use them to estimate how fast a person is aging. We go deeper in our guides to biological age and epigenetic clocks. Methylation is only one of several ways to put a number on biological age, and the trade-offs between the methods are compared in Biological age tests: what to measure and how to choose a method.

DO-HEALTH enrolled 777 older adults. Participants were randomly assigned to vitamin D (2000 IU/day), omega-3 (1 g/day) and/or a home exercise program, then followed for 3 years across several aging clocks at once: PhenoAge, GrimAge, GrimAge2 and DunedinPACE — the clock of the pace of aging. Of those four, PhenoAge is the one an ordinary blood panel can approximate, which is exactly what the PhenoAge Calculator — biological age from a blood test does.

What omega-3, vitamin D and exercise actually did

The main results:

• omega-3 on its own slowed several epigenetic clocks (PhenoAge, GrimAge2, DunedinPACE);
• the combination of omega-3 plus vitamin D plus exercise produced an additive effect on PhenoAge;
• taken separately, vitamin D and exercise had no significant effect on most of the clocks.

In other words, the biggest benefit did not come from one magic supplement but from a combination of factors, which fits the idea that longevity is built from several levers at once.

Why did omega-3 end up at the center of attention? These fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from oily fish, are a structural component of cell membranes and a major player in anti-inflammatory processes. Chronic inflammation is considered one of the key drivers of aging, and the ability of omega-3 to dampen it is a plausible biological explanation for why the supplement moved several independent aging clocks rather than one stray marker.

How big is the effect, really

Honesty matters here: the effect is modest. Translated into time, it amounts to slowing biological aging by a few months over 3 years. That is not rejuvenation and not a breakthrough headline, but for a cheap and safe intervention it is a visible and, more importantly, measurable result. The value of the work is that it is a randomized trial rather than an observation, which puts it closer to evidence of causation.

The small size of the effect is a sign of the study’s integrity, not its weakness. The supplement industry routinely promises years of rejuvenation with no evidence at all. Here, researchers honestly measured a small but real shift using a strict method. The right way to read that result is not as a reason to pin huge hopes on omega-3, but as confirmation that basic, affordable measures really do move the pace of aging a little, and do it reliably.

What this means for you

The practical conclusion matches what we already recommend: it is sensible to avoid a shortfall of omega-3 (from oily fish or a supplement) and vitamin D, and to stay physically active. We break it down in detail in our article on omega-3 and longevity. Do not expect a miracle from a capsule, but as part of an overall strategy omega-3 looks justified.

The additivity is the most telling part: omega-3, vitamin D and exercise stacked instead of competing. That reflects an important principle in aging science, which is that no single lever solves everything. Longevity is the sum of small contributions: nutrition, movement, sleep, sensible supplements. Each one alone does a little, together they add up to something noticeable, and this trial illustrates that logic inside a strict experiment. That stacking logic is the thread running through Longevity — the science of aging more slowly, which treats the pace of aging as something several ordinary habits nudge together rather than one decisive intervention.

In practice, that means you should stop looking for a single anti-aging pill. It is far more sensible to build a few basic habits and hold them for years. In that system omega-3 is not the star but a reliable everyday contributor: inexpensive, safe at reasonable doses, and backed by a growing evidence base. That is exactly how to think about it, as part of a whole rather than a stand-alone miracle.

Important caveats

The trial ran in relatively healthy older adults and lasted 3 years, so it did not measure long-term effects on actual lifespan, only surrogate markers (epigenetic clocks). How far a slower clock translates into extra years of healthy life — Healthspan (healthy life expectancy) — is still an open question. The direction, though, is encouraging.

Dose safety is worth remembering too. The trial used 1 g of omega-3 and 2000 IU of vitamin D per day, which are moderate, well-tolerated amounts. This is not a call for megadoses: an excess of fat-soluble vitamins and very high doses of fish oil are not harmless. As always, the sensible strategy is to cover the requirement rather than chase the idea that more is better, and if you take medication (especially anticoagulants), clear any supplement with your doctor.

Source: Bischoff-Ferrari HA, et al. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging (DO-HEALTH). Nat Aging. 2025. PubMed →

Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.