In a randomized clinical trial of older adults, researchers found that taking multivitamins for two years modestly slowed epigenetic markers of aging — equivalent to roughly four months less biological aging compared with a placebo.
Li et al. evaluated the two-year effect of daily multivitamin-multimineral supplements and cocoa extract (500 mg cocoa flavanols per day, including 80 mg epicatechin) on five DNA methylation measures of biological aging among 958 participants (482 women and 476 men) in the COSMOS study. Image credit: Ri Butov.
Epigenetic clocks estimate biological aging based on tiny changes in our DNA.
These clocks look at specific sites in our DNA that regulate gene expression and change naturally as we get older, helping track with mortality and the pace of aging.
“There is a lot of interest today in identifying ways to not just live longer, but to live better,” said Dr. Howard Sesso, a researcher at Brigham and Women’s Hospital and Harvard Medical School.
“It was exciting to see benefits of a multivitamin linked with markers of biological aging.
“This study opens the door to learning more about accessible, safe interventions that contribute to healthier, higher-quality aging.”
For their research, Dr. Sesso and his colleagues used data from the well-established COcoa Supplement Multivitamins Outcomes Study (COSMOS).
They analyzed DNA methylation data from blood samples of 958 randomly selected healthy participants with an average chronological age of 70.
The participants were randomized to take a daily cocoa extract and multivitamin; daily cocoa extract and placebo; placebo and multivitamin; or placebos only.
Samples were analyzed for changes in five epigenetic clocks from the start of the trial and at the end of the first and second years.
Compared to the placebo only group, people in the multivitamin group had slowing in all five epigenetic clocks, including statistically significant slowing seen in the two clocks that are predictive of mortality.
The changes equated to about four months less biological aging over the course of two years.
Additionally, people who were biologically older than their actual age at the start of the trial benefitted the most.
“We plan to do follow-up research to determine if the slowing of biological aging — observed through these five epigenetic clocks, and additional or new ones — persists after the trial ends,” said Dr. Yanbin Dong, a researcher at Augusta Univeristy.
“A lot of people take a multivitamin without necessarily knowing any benefits from taking it, so the more we can learn about its potential health benefits, the better,” Dr. Sesso added.
“Within COSMOS, we are fortunate and excited to build upon a rich resource of biomarker data to test how two interventions may improve biological aging and reduce age-related clinical outcomes.”
A paper on the findings was published this week in the journal Nature Medicine.
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S. Li et al. Effects of daily multivitamin-multimineral and cocoa extract supplementation on epigenetic aging clocks in the COSMOS randomized clinical trial. Nat Med, published online March 9, 2026; doi: 10.1038/s41591-026-04239-3