Multivitamin trial shows small but significant slowdown in biological aging — about four months over two years
A daily multivitamin did not turn back time, but it did appear to slow it—modestly. In a two-year randomized clinical trial of 958 older adults, researchers found small yet statistically significant changes on select epigenetic “aging clocks” among those receiving the supplement. Published in Nature Medicine and nested within the COcoa Supplement and Multivitamin Outcomes Study (COSMOS), the findings suggest a measurable, if limited, deceleration of biological aging that renews debate over what a routine multivitamin can and cannot do for healthy longevity.
Why this finding matters now
Biological age, distinct from years lived, is often assessed using DNA methylation patterns that correlate with aging and risk of disease. The new analysis focuses on whether slowing these epigenetic measures translates into better health. The results show a small effect size—about four months less biological aging over two years—raising timely questions about practical benefits for older adults and whether individual nutritional status shapes response to a multivitamin.
Researchers emphasize that more work is needed to connect clock measurements to real-world outcomes. The trial’s signals appear strongest among participants whose biological age was already running ahead of their chronological age at baseline, hinting that targeted supplementation might matter more than a blanket recommendation. Yet the modest magnitude reminds clinicians and the public that any gains, while detectable, remain incremental.
What the Multivitamin trial measured
The prespecified ancillary study assessed a daily multivitamin–multimineral (Centrum Silver) and a cocoa extract (500 mg cocoa flavanols per day, including 80 mg (−)-epicatechin) against matched placebos. Participants, with an average age of about 70 years, were randomized into four groups spanning all combinations of the two supplements and placebos. Blood samples at baseline, one year, and two years were analyzed across five DNA methylation clocks: PCHannum, PCHorvath, PCPhenoAge, PCGrimAge, and DunedinPACE.
Compared with placebo, the multivitamin arm showed a slower rate of epigenetic aging on two second-generation clocks tied to health and mortality risk. Yearly changes were reduced by −0. 113 years (95% CI −0. 205 to −0. 020; P = 0. 017) for PCGrimAge and by −0. 214 years (95% CI −0. 410 to −0. 019; P = 0. 032) for PCPhenoAge. The effect was stronger on PCGrimAge among those with accelerated biological aging at baseline (−0. 236) than among those with normal or decelerated aging (−0. 013; P = 0. 018 for interaction). Cocoa extract showed no effect on any of the five clocks and did not interact with the multivitamin.
The cohort included 482 women and 476 men, all within the larger COSMOS framework. The study team writes that the statistically significant but small differences warrant cautious interpretation until clinical endpoints—such as incident disease, functional status, or mortality—are explicitly linked to these clock changes.
Expert perspectives and broader impact
“There are no known risks for taking a multivitamin in our two large clinical trials. At the same time, we do not know for sure who benefits, and how, ” said Dr. Howard Sesso, epidemiologist at the Mass General Brigham department of medicine and senior author of the work. He added, “Nutritional status may partly explain the results, but these epigenetic clocks may reflect other age-related risk factors. ” Funding for the trial included support from Mars, a confectionery manufacturer, which has previously studied cocoa flavanols; in this analysis, the cocoa extract conferred no detectable slowing of epigenetic aging.
For policymakers and clinicians, the study underscores two realities: first, epigenetic clocks are sensitive tools that can register small shifts in biological aging; second, the path from such shifts to tangible health gains remains uncertain. The journal publication states that additional studies are needed to determine the clinical relevance of the observed clock changes and to test whether they help explain reductions in age-related conditions reported elsewhere in multivitamin research.
Regionally and globally, the implications are twofold. Health systems confronting aging populations may see value in low-cost interventions that generate even marginal improvements if they scale across millions. Yet public health guidance must remain evidence-based and outcome-driven. While these epigenetic results are encouraging, they do not constitute a directive for universal supplementation. Instead, they point to the potential of stratified approaches—identifying subgroups, such as those with accelerated biological aging or nutritional deficits, who might benefit most from a daily multivitamin.
As research continues within and beyond COSMOS, key questions involve durability, dose, and downstream impact. Do the observed changes persist beyond two years? Can nutrient formulations be tailored to maximize clock benefits without unintended trade-offs? And most importantly, will slowing epigenetic aging translate into fewer age-related diseases, improved cognition, or longer healthspan?
If future trials can link modest epigenetic gains to concrete outcomes, the case for a low-cost multivitamin as a standard tool for healthy aging could strengthen—yet for now, the science invites careful optimism and a focus on who stands to gain the most.
