A new analysis from the COSMOS trial suggests that taking a daily multivitamin for two years may modestly slow biological aging in older adults. The effect was strongest in people whose cells appeared older than their actual age at the start of the study.
A daily multivitamin might do more than fill nutritional gaps. It may also modestly slow how quickly our cells age, according to a new analysis from a large randomized clinical trial of older adults.
Researchers at Mass General Brigham report that participants who took a daily multivitamin for two years showed slower “biological age” on several DNA-based measures than those who took a placebo. On average, the difference was equivalent to about four months less biological aging over the study period, with the biggest gains seen in people who started out aging faster than their chronological age.
The findings, drawn from the long-running COcoa Supplement and Multivitamin Outcomes Study (COSMOS), are published in the journal Nature Medicine.
The work taps into growing scientific and public interest in how to extend not just lifespan, but healthspan — the number of years people stay healthy and independent.
“There is a lot of interest today in identifying ways to not just live longer, but to live better,” senior author Howard Sesso, an associate director of the Division of Preventive Medicine in the Mass General Brigham Department of Medicine, said in a news release.
Biological age versus birthday candles
The study focuses on biological age, a concept that reflects how old our bodies appear at the cellular and molecular level, which can differ from the number of years we have been alive.
To track this, the team used so-called epigenetic clocks. These tools estimate biological aging by measuring DNA methylation — small chemical tags on DNA that help control which genes are turned on or off. Patterns of DNA methylation change in predictable ways as people age and have been linked to mortality risk and the pace of aging.
In COSMOS, researchers analyzed DNA methylation data from blood samples of 958 randomly selected, generally healthy participants with an average age of 70. The participants had been randomly assigned to one of four groups: a daily cocoa extract plus a multivitamin, cocoa extract plus placebo, multivitamin plus placebo, or double placebo.
Blood samples were collected at the start of the trial and again after one and two years. The team then examined changes across five different epigenetic clocks to see whether the supplements appeared to influence biological aging.
Slower aging signal with multivitamins
Compared with the group that received only placebos, people who took a daily multivitamin showed slowing on all five epigenetic clocks. The slowing reached statistical significance in two clocks that are known to predict mortality.
Overall, the changes corresponded to about four months less biological aging over the two-year period. While that is a modest effect, it emerged in a relatively short time frame and in a group of older adults who were already in their 70s on average.
Importantly, the benefits were not evenly distributed. Participants whose biological age was higher than their chronological age at the start of the trial — meaning their cells looked older than their years — appeared to gain the most from multivitamin use.
Sesso noted the team was encouraged to see a measurable impact of a simple, widely available intervention on these cutting-edge aging markers.
“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,” he said.
What the study does — and does not — show
The COSMOS trial was originally designed to test whether cocoa extract and a daily multivitamin could reduce major health problems such as heart disease, cancer and other age-related conditions. The new analysis adds a layer by asking how those same interventions affect biological aging itself.
Because COSMOS is a randomized controlled trial, the gold standard in clinical research, the multivitamin findings carry more weight than results from observational studies, which can be skewed by lifestyle differences between supplement users and nonusers.
Still, the researchers caution that the study does not prove that multivitamins will help any individual live longer or avoid disease. Epigenetic clocks are powerful tools, but they are indirect markers. More work is needed to connect changes in these DNA-based measures to real-world outcomes like memory, mobility, cancer or vision problems.
Further studies are also planned to see whether the slowing of biological aging continues after people stop taking the study pills, and whether the effect grows, shrinks or plateaus over time.
“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,” added co-author Yanbin Dong, a director of the Georgia Prevention Institute at the Medical College of Georgia at Augusta University.
Next questions: cognition, cancer and more
The COSMOS team has already reported signs that a daily multivitamin may benefit cognition and may be linked to reductions in cancer and cataracts. Now they want to understand whether improvements in biological aging help explain those clinical findings.
If changes in epigenetic clocks turn out to track with better thinking skills, lower cancer risk or fewer age-related eye problems, those clocks could become valuable tools for testing future interventions aimed at healthy aging.
The researchers also plan to explore how multivitamins interact with other factors, such as diet, exercise, genetics and existing health conditions, to influence biological age. Since multivitamins are inexpensive and widely used, even modest benefits could have a large impact at the population level if confirmed.
Sesso noted that many people already take multivitamins without clear evidence of what they are getting in return.
“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,” he said.
He added that COSMOS provides a rare opportunity to dig deeply into these questions using stored blood samples and detailed health data collected over years of follow-up.
What it means for you
For now, experts emphasize that no pill can replace the foundations of healthy aging: not smoking, staying physically active, eating a balanced diet, getting enough sleep and managing conditions like high blood pressure and diabetes.
The new findings do not mean everyone should rush to start a multivitamin, nor do they settle ongoing debates about who benefits most from supplements. But they do suggest that, at least in older adults, a daily multivitamin might offer a small but measurable nudge toward slower biological aging, especially for those whose cells are aging faster than average.
As researchers continue to follow COSMOS participants and refine epigenetic clocks, they hope to move closer to a future where aging is not just something to endure, but a process that can be better understood — and perhaps, in modest ways, steered toward healthier years.
Source: Mass General Brigham