Does omega-3 slow your biological age?
Omega-3 modestly slows biological ageing on epigenetic clocks. The effect is small, and telomere length does not respond.
Omega-3 has a measurable but small effect on how quickly you age biologically, as measured by so-called biological age clocks. These clocks look at chemical tags on your DNA and produce an estimate of your biological age. In a large trial, older adults took 1 gram of omega-3 (EPA+DHA) daily for three years. On three of the four clocks measured, biological ageing was slightly slower: roughly 3 months over three years. That has been shown statistically, but it is a small difference, and it is not yet clear whether a clock reading like that actually means you will live longer or stay healthier.
People who also combined vitamin D and a home exercise programme gained an extra benefit on one of those clocks (PhenoAge). The idea that combining several approaches adds up to more is biologically easy to explain. However, not every clock showed an effect, which tells us the picture is not entirely straightforward.
For telomere length, another measure of how cells age, the story is different. Telomeres are the protective caps at the ends of your chromosomes, and shorter telomeres are linked to older cells. In a large four-year study with 1 gram of omega-3 per day, no effect on telomere length was found at all. An earlier overview of smaller studies reached the same conclusion: three out of three studies saw no meaningful effect. A mini-analysis of five very small studies (337 participants combined) did find a positive signal, but the researchers themselves called it preliminary. The large independent study is more conclusive here than the small ones.
If you want to try omega-3 with the goal of keeping tabs on your biological ageing, the only dose with a demonstrated effect is 1 gram of EPA+DHA per day, kept up for at least three years. This comes from a post-hoc analysis of one trial, meaning that outcomes on epigenetic clocks were not the primary aim of that study. Whether this translates into a real-world benefit remains an open question. Adding vitamin D and exercise does appear to contribute extra benefit on the PhenoAge clock.
This answer draws on one study in older adults looking at biological age clocks and one large study on telomere length. Two overviews of the existing evidence and a small pooled analysis of five very small studies were also taken into account. The biological age clock effect was found in one study that was not primarily designed to look for it; the researchers describe its real-world importance as uncertain. For telomere length, the large study found no effect and the smaller analyses point in different directions. The researchers behind the mini-analysis themselves cautioned that the evidence is preliminary and that larger studies are needed.