An analysis led by investigators at Mass General Brigham has found that daily multivitamin use may slow biological ageing in older adults. Drawing on data from a large, randomised clinical trial, the researchers observed that two years of supplementation was associated with measurable reductions in biological ageing, with the greatest benefits seen among individuals who entered the study with signs of accelerated ageing.
Biological age refers to how quickly the body is ageing at a cellular level, which may differ from a person’s chronological age. In this study, researchers examined multiple indicators of biological ageing over two years and found that participants taking a daily multivitamin experienced a modest but meaningful slowing of this process. The effect was equivalent to approximately four months less biological ageing compared with those who did not receive the supplement.
The findings, published in Nature Medicine, contribute to a growing body of research focused not only on extending lifespan but also on improving healthspan—the number of years lived in good health. According to senior author Howard Sesso, the results are particularly notable given the accessibility and safety profile of multivitamins. The study highlights the potential for relatively simple interventions to support healthier ageing trajectories.
To assess biological ageing, the research team used epigenetic clocks, which estimate ageing based on patterns of DNA methylation—small chemical modifications that regulate gene activity and change over time. These markers are increasingly recognised as reliable indicators of ageing and are associated with risks of disease and mortality. The analysis included blood samples from 958 healthy participants with an average age of 70, all drawn from the larger COSMOS trial.
Participants in the trial were randomly assigned to one of four groups: multivitamin and cocoa extract, multivitamin and placebo, cocoa extract and placebo, or double placebo. Over the course of two years, researchers measured changes across five established epigenetic clocks. Compared with the placebo group, those taking a multivitamin showed consistent slowing across all five measures, with statistically significant improvements observed in the clocks most strongly linked to mortality risk.
Importantly, the benefits were most pronounced among individuals whose biological age exceeded their chronological age at baseline, suggesting that those already experiencing accelerated ageing may derive greater value from supplementation. While these findings are promising, further research is needed to determine whether these effects persist over time and how they translate into real-world health outcomes, such as improved cognition or reduced risk of chronic conditions.
More information: Sidong Li et al, Effects of daily multivitamin–multimineral and cocoa extract supplementation on epigenetic aging clocks in the COSMOS randomized clinical trial, Nature Medicine. DOI: 10.1038/s41591-026-04239-3
Journal information: Nature Medicine Provided by Mass General Brigham
