A major randomized clinical trial suggests that a simple daily multivitamin could help slow how quickly our bodies age at the cellular level. Researchers from Harvard and Mass General Brigham analyzed data from 958 healthy adults with an average age of 70 and found that those taking a daily multivitamin-multimineral supplement for two years showed measurable slowing in biological aging markers compared to those taking a placebo .

What Is Biological Aging and Why Does It Matter?

Biological age is different from how many years you've lived. It measures how quickly your body is aging at the cellular level, and it can be faster or slower than your chronological age. Scientists estimate biological age using "epigenetic clocks," which track tiny chemical changes in DNA called DNA methylation that naturally occur as we get older . These changes help predict mortality risk and overall aging pace.

The distinction matters because two people born in the same year can have very different biological ages. Someone might be 70 years old chronologically but have the cellular age of a 65-year-old, or vice versa. This is why researchers are increasingly interested in interventions that might slow biological aging, not just extend lifespan .

What Did the Study Find About Multivitamins and Aging?

The research, published in Nature Medicine, used data from the COcoa Supplement Multivitamins Outcomes Study (COSMOS), a well-established randomized clinical trial. Participants were randomly assigned to one of four groups:

• Daily cocoa extract and multivitamin: Received both supplements for the full two-year period
• Daily cocoa extract and placebo: Received cocoa extract but no multivitamin
• Placebo and multivitamin: Received multivitamin but no cocoa extract
• Placebos only: Served as the control group for comparison

Researchers analyzed blood samples from participants at the start of the trial and at the end of years one and two, measuring changes in five different epigenetic clocks. The results showed that people taking the multivitamin had slowing in all five epigenetic clocks compared to the placebo-only group. Most importantly, two of these clocks that are specifically predictive of mortality showed statistically significant slowing . The overall effect was equivalent to about four months less biological aging over the two-year period.

The benefits were not uniform across all participants. Those who started the trial with biological ages older than their actual chronological age benefited the most from the multivitamin, suggesting the supplement may be particularly helpful for people whose bodies are aging faster than expected .

How to Interpret These Results Responsibly

While the findings are encouraging, experts emphasize that the results are modest and require careful interpretation. Not all five epigenetic clocks measured in the study showed statistically significant changes. Three of the five clocks showed no meaningful difference between the multivitamin and placebo groups .

• Study limitations: The research did not account for participants' exact diets or physical activity levels during the two years, both of which can significantly affect biological aging
• Modest magnitude: The four-month slowing of biological aging is a small effect, and experts note that the clinical significance of this change remains uncertain
• Need for follow-up: Researchers plan additional studies to determine whether the slowing persists after the trial ends and whether it translates to real-world health improvements like reduced disease risk or extended lifespan

"There is a lot of interest today in identifying ways to not just live longer, but to live better. 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," said Howard Sesso, associate director of the Division of Preventive Medicine at Mass General Brigham.

Howard Sesso, Associate Director of the Division of Preventive Medicine, Mass General Brigham

José Ordovás, a professor of nutrition and genetics at Tufts University who was not involved in the study, noted that while the findings are interesting, they fall short of proving that multivitamins broadly slow aging or improve longevity. The fact that only two of five epigenetic clocks showed significant changes suggests the effect may be more limited than headlines might suggest .

What Happens Next in Multivitamin Research?

The COSMOS research team plans several follow-up investigations to build on these findings. They will examine whether the slowing of biological aging persists after participants stop taking the supplement, and they will investigate how improvements in biological aging might connect to actual health outcomes like reduced cancer risk, better cognition, and fewer cataracts, all areas where COSMOS has already found some evidence of benefit .

Researchers also want to understand whether the benefits extend beyond older adults to younger age groups, and whether specific nutrients within the multivitamin are responsible for the effect. These questions remain unanswered by the current study .

"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," said Sesso.

Howard Sesso, Associate Director of the Division of Preventive Medicine, Mass General Brigham

It's important to note that multivitamins are not FDA-approved for any specific health claim, and the science on their overall effectiveness remains mixed . This study adds one piece of evidence suggesting potential benefits for biological aging in older adults, but it does not mean multivitamins are a proven anti-aging treatment or a substitute for other healthy behaviors like exercise, good nutrition, and sleep.

For people considering whether to take a multivitamin, this research suggests that a daily supplement may offer modest benefits related to cellular aging, particularly for older adults. However, experts recommend consulting with a healthcare provider about whether supplementation makes sense for your individual health situation, rather than assuming all multivitamins will produce the same results .