Omega-3 Slowed Biological Ageing in a 3-Year Trial
The finding: One gram of omega-3 a day slowed measures of biological ageing by roughly three months over three years. Combining it with vitamin D and exercise added further benefit again.
What they did
The DO-HEALTH trial randomly allocated 777 adults aged 70 and over to vitamin D (2,000 IU a day), omega-3 (1 g a day), a home exercise programme, or combinations of the three, and followed them for three years. Nobody knew who was taking the real supplement and who was taking the placebo.
The researchers then measured biological ageing using four DNA methylation clocks: PhenoAge, GrimAge, GrimAge2 and DunedinPACE. These read chemical marks on DNA that shift predictably with age, and they are currently the best tools we have for estimating how fast a body is ageing rather than how many birthdays it has had. The results were published in Nature Aging.
What they found
- Omega-3 on its own slowed three of the four clocks: PhenoAge, GrimAge2 and DunedinPACE.
- On the PhenoAge clock, all three treatments together produced an additive benefit, meaning the combination did more than omega-3 alone.
- Across the clocks, effect sizes ranged from 0.16 to 0.32 standardised units, which the authors translate to 2.9 to 3.8 months of biological ageing over the three years.
- The clocks were analysed after the trial had finished rather than being its original endpoint. The authors summarise the result as an indication of a small protective effect of omega-3 on slowing biological ageing.
What this means for you
The dose used here was modest: 1 g a day of marine omega-3. That is not a heroic amount, and it is in the range most good omega-3 supplements and a couple of oily fish meals a week will give you.
The additive result is the most useful part. Omega-3, vitamin D and movement together did more on the PhenoAge clock than any of them on its own, which fits the unglamorous truth of this whole field: the basics stack, and they stack better together than separately.
Three years is the timeframe to hold in mind. The clocks measure something that shifts slowly by nature, so this is a long game rather than a quick one.
The study
Bischoff-Ferrari HA, Gangler S, Wieczorek M, et al. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging in older adults from the DO-HEALTH trial. Nature Aging. 2025 Mar;5(3):376-385.
General information only. This is a summary of published research, not a therapeutic claim and not medical advice. A result found in a trial population is not the same as a product doing that for you. Always read the label and follow the directions for use. If you have a health condition or take medication, check with your health practitioner before use.
