How quickly our bodies age on a cellular level — our “biological age” — can differ from how old we actually are in years. Using data from a large randomized clinical trial of older adults, researchers from Harvard and Mass General Brigham evaluated the effects of taking a daily multivitamin over the course of two years on five measures of biological aging and found a slowing equivalent to about four months of aging. The benefits were increased in those who were biologically older than their actual age at the start of the trial. The results are published in Nature Medicine.

“There is a lot of interest today in identifying ways to not just live longer, but to live better,” said senior author Howard Sesso, a preventive medicine specialist at Mass General and a Harvard Chan School epidemiologist. “It was exciting to see the 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.”

Epigenetic clocks estimate biological aging based on tiny changes in DNA. These clocks look at specific sites in our DNA that regulate gene expression (known as DNA methylation) and change naturally as we get older, helping track mortality and the pace of aging.

The new study, which uses data from the well-established COcoa Supplement Multivitamins Outcomes Study (COSMOS), analyzed DNA methylation data from blood samples of 958 randomly selected healthy participants with an average chronological age of 70.

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 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 benefited 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 co-author and collaborator Yanbin Dong of the Medical College of Georgia, Augusta University.

Said Sesso: “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.”

The study received funding from the National Institutes of Health.