Daily Multivitamin Slows Biological Aging by 4 Months in Large Clinical Trial
A Mass General Brigham trial found multivitamin users aged slower on 5 epigenetic clocks, with the biggest gains in those aging fastest.
Summary
A large randomized clinical trial from Mass General Brigham found that taking a daily multivitamin for two years slowed biological aging in older adults, as measured by five DNA-based epigenetic clocks. The effect was equivalent to about four fewer months of biological aging over the study period. Notably, participants whose biological age already exceeded their chronological age at the start showed the greatest benefit. The study, published in Nature Medicine, tracked 958 healthy adults with an average age of 70, comparing multivitamin users against placebo groups. Two of the five clocks tested — those most strongly linked to mortality risk — showed statistically significant slowing. Researchers see this as early but promising evidence that an accessible, low-cost supplement could meaningfully support healthier aging at the cellular level.
Detailed Summary
Biological aging — how fast your body ages at the cellular level — does not always match the number of candles on your birthday cake. A new study published in Nature Medicine suggests that something as simple as a daily multivitamin may help slow this process in older adults, offering a potentially accessible tool in the longevity toolkit.
Researchers from Mass General Brigham analyzed data from 958 healthy adults averaging 70 years old who participated in the COSMOS (COcoa Supplement and Multivitamin Outcomes Study) randomized clinical trial. Participants were assigned to one of four groups combining multivitamins or cocoa extract with placebos. Biological aging was measured using five epigenetic clocks — tools that estimate aging speed by analyzing DNA methylation patterns, chemical tags on DNA that shift predictably with age and correlate with disease risk and mortality.
After two years, participants taking a daily multivitamin showed slower biological aging across all five epigenetic clocks compared to placebo-only participants. Two of the clocks, those most closely tied to mortality risk, reached statistical significance. The overall effect translated to approximately four months less biological aging over the study period — a modest but meaningful signal given the low cost and safety profile of the intervention.
The most compelling finding was the differential benefit: participants who were biologically older than their chronological age at baseline appeared to gain the most from multivitamin supplementation. This suggests the intervention may be especially valuable for individuals already on an accelerated aging trajectory.
Caveats are worth noting. The study involved only 958 participants from a larger trial, the two-year window is relatively short, and epigenetic clocks — while validated — are still surrogate markers rather than direct health outcomes. Whether this biological slowing translates to longer life or reduced disease burden requires further study. Follow-up research is planned to assess whether effects persist post-trial.
Key Findings
- Daily multivitamin use slowed biological aging by approximately 4 months over a 2-year period in adults averaging age 70.
- Two epigenetic clocks most strongly linked to mortality risk showed statistically significant slowing in multivitamin users.
- Participants biologically older than their chronological age at baseline experienced the greatest anti-aging benefit.
- Slowing was observed across all five DNA methylation-based epigenetic clocks compared to placebo groups.
- Findings were published in Nature Medicine from a randomized controlled trial, offering higher-quality evidence than observational studies.
Methodology
This is a research summary based on a peer-reviewed randomized clinical trial published in Nature Medicine, sourced from Mass General Brigham — a highly credible academic medical institution. The evidence basis is a subset analysis of 958 participants from the larger COSMOS trial, using validated epigenetic clock measurements from blood samples taken at baseline, one year, and two years.
Study Limitations
The 958-participant subsample is relatively small for drawing population-wide conclusions, and epigenetic clock deceleration is a surrogate endpoint — not a direct measure of disease reduction or lifespan extension. The specific multivitamin formulation used in COSMOS may differ from over-the-counter products, and long-term persistence of effects beyond two years remains unconfirmed pending follow-up research.
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