Vitamins, Aging, and Brain Health: What New Research Reveals
Two new studies are adding to growing scientific interest in how common nutritional supplements may influence aging and long-term brain health. One large clinical trial suggests that a daily multivitamin could modestly slow biological aging in older adults, while another study found that higher vitamin D levels in midlife were linked to lower levels of a dementia-related protein years later.
Although researchers caution that neither study proves supplements can prevent aging or dementia, the findings point toward potentially accessible strategies for supporting healthier aging.
Daily Multivitamins May Slow Biological Aging
A major clinical trial led by researchers at Mass General Brigham found that taking a daily multivitamin for two years was associated with slower biological aging in older adults.
The study, published in Nature Medicine, analyzed data from participants in the Cocoa Supplement Multivitamins Outcomes Study (COSMOS), a long-running randomized clinical trial involving healthy older adults.
Researchers examined blood samples from 958 participants with an average chronological age of 70. Instead of simply measuring age in years, scientists focused on “biological age,” which reflects how quickly the body is aging at the cellular level.
How Biological Aging Was Measured
To estimate biological aging, researchers used tools known as “epigenetic clocks.” These clocks analyze chemical changes in DNA called DNA methylation, which naturally shift over time and influence gene activity.
By studying these patterns, scientists can estimate how quickly a person’s body is aging and assess risks tied to disease and mortality.
Participants in the COSMOS trial were randomly assigned to one of four groups:
- Daily cocoa extract plus multivitamin
- Daily cocoa extract plus placebo
- Daily multivitamin plus placebo
- Double placebo
Researchers compared five different epigenetic aging measurements at the start of the study and again after one and two years.
What the Researchers Found
Across all five epigenetic clocks, participants taking a daily multivitamin showed slower biological aging compared with those receiving only placebos. Two of the measurements—both strongly linked to mortality risk—showed statistically significant improvements.
Overall, the effect was equivalent to roughly four fewer months of biological aging over the two-year study period.
The strongest benefits appeared in participants whose biological age was already more advanced than their actual chronological age when the trial began.
Senior author Howard Sesso said the findings contribute to a broader effort to identify ways not only to extend lifespan but also to improve quality of life during aging.
Researchers emphasized, however, that more studies are needed to determine whether these biological changes translate into measurable long-term health benefits.
Potential Connections to Brain Health
The COSMOS research team is continuing to investigate whether slower biological aging could help explain earlier findings linking multivitamin use to improved cognition and reduced risks of conditions such as cancer and cataracts.
Scientists hope future studies will reveal whether these DNA-based aging changes persist even after supplementation ends.
Vitamin D Levels May Influence Brain Aging
A separate study published in April 2026 in Neurology Open Access explored how vitamin D levels in midlife may affect brain health decades later.
Researchers found that people with higher vitamin D levels around age 39 tended to have lower levels of tau protein in the brain approximately 16 years later.
Tau protein is strongly associated with Alzheimer’s disease and other forms of dementia.
Study author Martin David Mulligan of University of Galway said the findings suggest vitamin D deficiency could potentially represent a modifiable risk factor for dementia.
Inside the Study
The study followed 793 adults who were free of dementia at the beginning of the research.
At the start of the study, researchers measured blood vitamin D levels. Sixteen years later, participants underwent brain scans to assess two Alzheimer’s-related biomarkers:
- Tau protein
- Amyloid beta protein
Vitamin D levels above 30 nanograms per milliliter (ng/mL) were considered high, while levels below that threshold were classified as low.
Researchers found:
- 34% of participants had low vitamin D levels
- Only 5% reported taking vitamin D supplements
- Higher vitamin D levels were linked to lower tau protein accumulation years later
- No significant relationship was found between vitamin D levels and amyloid beta protein
After adjusting for factors such as age, sex, and depression symptoms, the association between vitamin D and lower tau burden remained significant.
Important Limitations
Researchers stressed that the findings show correlation rather than proof of cause and effect.
The vitamin D study measured participants’ vitamin D levels only once, making it unclear whether long-term vitamin D status may have changed over time. Likewise, the multivitamin study showed modest effects and did not prove that supplementation directly extends lifespan or prevents disease.
Still, both studies highlight growing scientific interest in how nutrition may influence aging at the molecular and neurological levels.
What These Findings Mean
Together, the studies suggest that nutritional factors may play a meaningful role in ealthy aging and brain health, particularly during midlife and older adulthood.
Key takeaways include:
- Daily multivitamin use may modestly slow biological aging in older adults
- Higher vitamin D levels in midlife were linked to lower levels of tau protein later in life
- Neither study proves supplements prevent dementia or aging-related disease
- Researchers believe more long-term studies are needed before firm recommendations can be made
For now, scientists say the findings support continued investigation into simple, low-cost interventions that could help people maintain better health as they age.
Effects of daily multivitamin–multimineral and cocoa extract supplementation on epigenetic aging clocks in the COSMOS randomized clinical trial. Nature Medicine, 2026; 32 (3): 1012 DOI: 10.1038/s41591-026-04239-3
Association of Circulating Vitamin D in Midlife With Increased Tau-PET Burden in Dementia-Free Adults. Neurology Open Access, 2026; 2 (2) DOI: 10.1212/WN9.0000000000000057