A large clinical trial suggests that taking a daily multivitamin could help slow biological aging in older adults, especially in people whose bodies were aging faster than expected at the start of the study.
Researchers from Mass General Brigham analyzed data from older adults who participated in a randomized clinical trial and found that two years of multivitamin use was linked to slower biological aging across several DNA-based measurements.
The effect was equal to roughly four fewer months of biological aging over the course of the study.
How scientists measure biological aging
Biological age is an estimate of how fast or slow your cells, tissues and organ systems are aging, rather than simply how many years you have lived (chronological age).
It’s influenced by genetics, health status, diet, physical activity, sleep habits, smoking and alcohol use and stress.
Different tests are used to estimate biological age.
One method involves using epigenetic clocks – tools that read small molecular tags on DNA, called epigenetic markers, that change in predictable ways with age. These changes alter how cells function, repair themselves and respond to stress.
If a person’s epigenetic markers on DNA show patterns usually seen in older people, epigenetic clocks estimate their biological age as higher.
Epigenic clocks are considered among the most precise biomarkers of biological aging.
About the study
The new research used information from the COcoa Supplement Multivitamins Outcomes Study (COSMOS), a long-running clinical trial involving older adults.
Investigators examined DNA methylation data from blood samples collected from 958 healthy participants whose average chronological age was 70.
Participants in the trial were randomly assigned to one of four groups: daily cocoa extract and multivitamin; daily cocoa extract and placebo; placebo and multivitamin; or placebo only.
Researchers compared changes in five separate epigenetic clocks at the beginning of the study and again after one and two years.
Daily multivitamin use linked to slower aging
Compared with participants who received only placebos, those taking a multivitamin showed slower biological aging across all five measurements. Two of the clocks, which are strongly associated with mortality risk, showed statistically significant slowing.
Overall, the findings suggested that multivitamin use reduced biological aging by about four months during the two-year period.
The strongest effects appeared in participants whose biological age was already ahead of their chronological age when the trial began.
Possible links to brain health
More work is needed to understand how slowing biological aging may influence long-term health outcomes.
In an analysis of a subset of COSMOS participants, the researchers found that lower levels of carotenoids and vitamin E in the bloodstream were associated with accelerated biological aging at baseline.
It’s possible that by improving nutritional status, a daily multivitamin can benefit biological aging.
The COSMOS team plans to continue studying whether the effects of daily multivitamin use could help explain previous findings connected to improved cognition and lower risks of cancer and cataracts.
Source: Nature Medicine, March 9, 2026.
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