🟠 Moderate Evidence
A new randomized controlled trial published in Nature Medicine has found that daily multivitamin supplementation can slow two of five epigenetic aging clocks over a two-year period, with the strongest effects observed in individuals who showed faster biological aging at baseline. The study, led by researchers analysing data from the COSMOS (COcoa Supplement and Multivitamin Outcomes Study) trial, suggests that micronutrient supplementation may offer measurable benefits for slowing age-related biological changes at the molecular level.
Key takeaways
- Daily multivitamin supplementation slowed 2 of 5 epigenetic aging clocks in a two-year randomized trial, with benefits most pronounced in faster-aging individuals
- Three COSMOS substudies involving 5,203 participants found that multivitamin use delayed cognitive aging by approximately 2 years compared to placebo
- Effects on epigenetic aging varied by clock type, suggesting that different biological aging pathways may respond differently to micronutrient intervention
- Cognitive benefits emerged across multiple independent substudies, strengthening evidence for a protective effect on age-related cognitive decline
Study at a Glance
| Source | Nature Medicine |
| Study type | Randomized controlled trial with secondary analyses |
| Sample size | 5,203 participants across three cognitive substudies; broader COSMOS cohort |
| Population | Adults followed over two years; cognitive subgroup analysed for aging effects |
| Country | United States (COSMOS multicenter trial) |
Multivitamin Effects on Epigenetic Aging Clocks and Cognitive Function
Two-year randomized trial data from Li et al., Nature Medicine 2026
Source: Li et al., Nature Medicine, 2026 | Georgian Medical Journal News
Epigenetic clocks provide a molecular window on aging
Epigenetic clocks—mathematical models based on chemical modifications to DNA that accumulate with age—have emerged as precise biomarkers of biological aging independent of chronological age. Unlike traditional aging measures, epigenetic clocks capture molecular-level changes associated with disease risk and mortality. The Li et al. study in Nature Medicine analysed five different epigenetic aging clocks to assess whether multivitamin supplementation could slow these biological aging processes.
The researchers found that daily multivitamin use significantly slowed two of the five epigenetic clocks over the two-year follow-up period. Notably, the benefit was most pronounced in participants who demonstrated faster epigenetic aging at baseline—a subgroup that may carry higher disease risk and would theoretically benefit most from interventions slowing aging. This differential effect suggests that multivitamins may be particularly beneficial for individuals with accelerated aging profiles, though the mechanism by which micronutrient supplementation influences epigenetic modifications remains to be fully elucidated.
Cognitive benefits emerge across multiple independent substudies
Beyond epigenetic markers, the broader COSMOS trial generated striking findings on cognitive aging. According to data from three independent cognitive substudies totalling 5,203 participants, daily multivitamin supplementation delayed cognitive aging by approximately 2 years compared to placebo. This effect size—equivalent to a two-year slowing of cognitive decline—is substantial and clinically meaningful in the context of age-related cognitive impairment and dementia prevention.
The cognitive benefits persisted across multiple independent study cohorts within COSMOS, reducing the likelihood of spurious findings and strengthening confidence in the protective effect. The convergence of evidence across three separate analyses suggests a robust signal rather than noise or bias. Clinical Updates from the latest trials increasingly highlight cognitive preservation as a priority outcome in aging research, making these findings particularly relevant to clinicians and public health planners.
Daily multivitamin supplementation delayed cognitive aging by approximately 2 years compared to placebo across three COSMOS cognitive substudies involving 5,203 participants, suggesting measurable neuroprotective benefits from micronutrient supplementation.
— Li et al., Nature Medicine, 2026
Mechanisms and implications for micronutrient intervention
The mechanisms by which multivitamins might slow epigenetic aging and protect cognitive function remain incompletely understood, but several pathways merit consideration. Micronutrients including B vitamins (folate, B6, B12), antioxidants (vitamins C and E), and minerals (zinc, selenium) play established roles in DNA methylation, mitochondrial function, and neuroinflammation—all relevant to aging pathways. The differential effect on individual epigenetic clocks suggests that different aging mechanisms may respond selectively to micronutrient supplementation, a finding that warrants deeper mechanistic investigation.
The COSMOS cognitive findings align with growing evidence that nutritional interventions can influence cognitive trajectory in aging populations. However, the study’s randomized design and large sample size across three substudies provide stronger evidence than observational studies typically afford. New Studies in gerontology and preventive medicine increasingly employ epigenetic and cognitive endpoints alongside traditional biomarkers, reflecting recognition that biological aging signatures may better predict health outcomes than calendar age alone.
What this means
Frequently asked questions
What are epigenetic clocks and why do they matter?
Epigenetic clocks are mathematical models of age-related DNA methylation patterns that predict biological aging independent of chronological age. According to research cited in gerontology literature, individuals with advanced epigenetic ages relative to their chronological age show elevated risk of age-related disease and mortality, making these clocks valuable biomarkers for studying aging interventions.
Does this study prove multivitamins prevent dementia?
The COSMOS cognitive substudies demonstrate that multivitamins delayed cognitive aging by approximately two years compared to placebo—a substantial effect—but longer follow-up would be needed to establish whether this translates to dementia prevention. The two-year cognitive benefit is clinically meaningful, but confirmation in additional trials and mechanistic studies would strengthen the evidence base for dementia prevention claims.
Which multivitamin formulations were studied, and do all multivitamins show similar benefits?
The COSMOS trial used a standardized multivitamin formulation provided to all participants. Different multivitamin brands and compositions vary in micronutrient content and bioavailability, and the specific formulation used in COSMOS may not be directly comparable to all commercial multivitamins. Patients should consult their physician about which formulations, if any, are appropriate for their individual health profile and existing medications.
The Li et al. findings published in Nature Medicine represent a significant advance in understanding how micronutrient supplementation may modulate aging at the molecular and cognitive levels. With the growing emphasis on preventive aging research, additional studies are warranted to characterize which populations benefit most from supplementation, which micronutrient combinations are most effective, and whether short-term epigenetic benefits translate to long-term reductions in age-related disease burden. The convergence of evidence across epigenetic and cognitive domains suggests that comprehensive aging interventions—combining micronutrient optimization, exercise, cognitive engagement, and cardiovascular health—may offer additive benefits for healthy aging trajectories.
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