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In this article
The key points at a glance
- The ‘omega-3 study from Zurich’ that people search for is most likely DO-HEALTH: for three years, 2,157 people aged 70 and over received omega-3, vitamin D, a home exercise programme, a combination of these, or a placebo1.
- For the six primary outcomes, the study found no statistically significant benefit, and that includes omega-32.
- A later (post hoc) analysis of 777 participants found that three of four measures of biological ageing progressed somewhat more slowly with omega-3. The authors themselves describe it as a small effect3.
- One example of an authorised health claim: ‘DHA contributes to maintenance of normal brain function’, based on a daily intake of 250 mg DHA4.
Which study from Zurich is meant?
DO-HEALTH is a large study of 2,157 women and men aged 70 and over from several European countries1. The first author and much of the team came from the University of Zurich and University Hospital Zurich, working with partners at other centres1. The participants lived at home, were mobile enough and mentally fit, and had had no major health events in the previous five years1,2.
Three things were tested: 1 g of omega-3 from marine algae a day (330 mg EPA and 660 mg DHA), 2,000 IU of vitamin D a day, and 30 minutes of strength training at home three times a week1,3. The study was randomised, so chance decided which of eight groups each participant joined: each measure on its own, all the combinations, or placebo, with stretching exercises as the comparison training1,2.
The study was double-blind, ran for three years, and 88% of participants stayed to the end2. It was funded by the EU, the University of Zurich and several companies, which, according to the study, had no influence on its design or analysis2.
What did the main study find?
The study had six primary outcomes, among them physical and cognitive performance and bone fractures2. After three years, none of them showed a statistically significant benefit, whether for omega-3, vitamin D or training, on their own or combined2.
That result matters precisely because the study was so large and so carefully designed. It does, however, apply only to these six outcomes and to a group of healthy, mobile people aged 70 and over2. How to read results like these is explained in our article on understanding the evidence. Our article on vitamin D3 and K2 studies explains what studies of vitamin D combined with K2 measure.
2,157
People aged 70 and over took part in DO-HEALTH for three years1.
2.9 to 3.8 months
The difference in measured biological age over three years3.
What did the analysis of biological age show?
A further analysis was published in 2025: in 777 participants, the researchers looked at four so-called epigenetic clocks3. These measures use chemical marks on the genome (DNA methylation) to estimate how fast a person is ageing biologically3.
With omega-3 alone, three of the four clocks progressed more slowly than without it. For one of the clocks, omega-3, vitamin D and training together showed an additional effect3. Overall, the differences came to about 2.9 to 3.8 months over three years, and the authors themselves call this a small effect3.
One point to bear in mind when interpreting this: the analysis was carried out afterwards (post hoc) and wasn't one of the study's original main questions3. Epigenetic clocks are markers. And the study doesn't answer what a difference of a few months means for everyday health.
Good to know Only people aged 70 and over who were healthy and mobile enough at the start took part in DO-HEALTH2. That's why the results can't simply be applied to younger people or other groups, nor to other amounts or products.
What health claims are authorised for omega-3?
The omega-3 fatty acids EPA and DHA have authorised health claims. For DHA, these include ‘DHA contributes to maintenance of normal brain function’ and ‘DHA contributes to the maintenance of normal vision’, each based on a daily intake of 250 mg DHA. For both fatty acids together, there is ‘EPA and DHA contribute to the normal function of the heart’, based on a daily intake of 250 mg EPA and DHA4.
On safety, EFSA concluded that supplemental intakes of up to 5 g of EPA and DHA combined per day are safe for adults5. Dietary recommendations for adults in Europe range from 250 to 500 mg of EPA and DHA a day5. Do not exceed the recommended daily amount. Melinava offers Omega 3, manufactured to European pharmaceutical quality.
Frequently asked questions about the omega-3 study from Zurich
What did the omega-3 study from Zurich find?
For six primary outcomes, such as physical and cognitive performance, DO-HEALTH found no statistically significant benefit2. In a later analysis, three of four measures of biological ageing progressed somewhat more slowly with omega-33.
How much omega-3 was given in the Zurich study?
Participants took 1 g of omega-3 from marine algae a day, of which 330 mg was EPA and 660 mg DHA, for three years1,3. That's well below the amount EFSA considers safe for adults5.
What does the evidence on omega-3 show overall?
No single study can stand for the whole body of evidence, not even one as large as DO-HEALTH. But it does show how mixed results can be: no benefit for the primary outcomes, and a small difference in biological age2,3. For EPA and DHA, certain health claims are authorised, for example on the normal function of the heart4.
Sources
- Bischoff-Ferrari HA, de Godoi Rezende Costa Molino C, Rival S, et al. (2021). DO-HEALTH: Vitamin D3, Omega-3, Home exercise, Healthy aging and longevity trial. Design of a multinational clinical trial on healthy aging among European seniors. Contemporary Clinical Trials 100:106124. DOI
- Bischoff-Ferrari HA, Vellas B, Rizzoli R, et al. (2020). Effect of Vitamin D Supplementation, Omega-3 Fatty Acid Supplementation, or a Strength-Training Exercise Program on Clinical Outcomes in Older Adults: The DO-HEALTH Randomized Clinical Trial. JAMA 324(18):1855-1868. DOI
- Bischoff-Ferrari HA, Gängler S, Wieczorek M, et al. (2025). 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 5(3):376-385. DOI
- European Commission (2012). Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health (consolidated version of 17 May 2021). Link
- EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (2012). Scientific Opinion on the Tolerable Upper Intake Level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). EFSA Journal 10(7):2815. DOI
This article is for general information only and should not replace medical advice. Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Written by
Melinava Editorial Team