Omega-3 Slowed Biological Aging in a 3-Year Trial

Medically reviewed by Lauren Orta, FNP-C

In a 3-year randomized trial, 1 gram of omega-3 a day slowed DNA-based aging clocks by roughly 3 to 4 months. Adding vitamin D and home exercise stacked the benefit on one clock.

TL;DR

• 777 healthy, active adults aged 70+ in Switzerland were randomized to omega-3, vitamin D, home exercise, or combinations.
• Omega-3 alone slowed three of four DNA aging clocks (PhenoAge, GrimAge2 and DunedinPACE).
• The effect was small: about 2.9 to 3.8 months less biological aging over 3 years.
• All three together had an additive effect on PhenoAge.

What the study did

DO-HEALTH is a large European trial of 2,157 generally healthy adults aged 70 and older. It used a 2×2×2 design: participants were randomized to vitamin D3 (2,000 IU/day) or placebo, omega-3 (1 g/day, 330 mg EPA plus 660 mg DHA from algae) or placebo, and a simple home strength-training program (30 minutes, 3 times a week) or a flexibility control program, for 3 years.

This analysis, published in Nature Aging in 2025 (PubMed 39900648; full text on PMC; DOI 10.1038/s43587-024-00793-y), measured "epigenetic clocks" in 777 Swiss participants. These clocks read chemical tags on DNA to estimate how fast the body is aging, separate from birthday age. Average age was 75.5.

What it found

• Omega-3 alone slowed three clocks: PhenoAge, GrimAge2 and DunedinPACE.
• Size of the effect: standardized effects of 0.16 to 0.32, equal to about 2.9 to 3.8 months less biological aging over 3 years.
• Stacking: omega-3, vitamin D and exercise together had additive benefits on PhenoAge.
• Context from the full trial: in all 2,157 participants, omega-3 alone cut infections by 13% and falls by 10%, and all three together cut pre-frailty by 39%.

What it means for you

Basic, cheap habits can move markers of aging, and the effects add up. A gram of omega-3, a moderate vitamin D dose and three short strength sessions a week are about as low-cost as health interventions get.

Keep the size in perspective. A few months over 3 years is real but modest. It's a nudge, not a time machine. The big levers for men are still lifting, sleep, body fat and treating real medical problems like low T. See exercise and testosterone, does vitamin D boost testosterone?, testosterone and aging and the best supplements to take on TRT. For omega-3 and the heart specifically, read our REDUCE-IT breakdown.

The fine print

• This was a post hoc analysis: the aging clocks weren't the trial's original main outcomes.
• Participants were healthy, active Swiss adults 70+, and about 60% were women. Results may differ for younger men.
• Epigenetic clocks are research tools. Slowing a clock isn't proven to mean living longer.
• Omega-3 didn't move every clock (GrimAge didn't change significantly).
• One author founded a nonprofit that licenses epigenetic clock patents, including GrimAge.

FAQ

Does omega-3 slow aging?

In the DO-HEALTH trial, 1 g/day of omega-3 slowed three DNA-based aging clocks over 3 years, by about 3 to 4 months. The effect was small and measured in adults aged 70 and older.

How much omega-3 was used?

1 gram per day of algae-based omega-3 (330 mg EPA plus 660 mg DHA), taken for 3 years. Fish oil supplies the same two fats, though the trial did not test fish oil itself.

Do vitamin D and exercise add to the effect?

Yes, on one clock. Omega-3, vitamin D (2,000 IU/day) and a home strength program together had an additive benefit on PhenoAge.

Does this mean omega-3 helps you live longer?

Not proven. Epigenetic clocks estimate biological age, but slowing them hasn't been shown to extend lifespan.

Next step

Omega-3 is the easy part. If energy, drive or recovery have slipped, check your hormones. Book a free consult or learn about TRT at AZTRT. AZTRT serves men in Arizona through licensed telehealth providers.

Sources

1. Bischoff-Ferrari HA 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. Nat Aging. 2025;5(3):376-385. PubMed · DOI

This article is for education, not medical advice. Treatment decisions are made with a licensed provider after an evaluation and labs. Results vary.