Multivitamins and Cognitive Aging

There has been a lack of clinical trial evidence demonstrating that regular intake of multivitamins provides a significant health benefit for otherwise healthy people. Even so, millions of people regularly take vitamins as a form of “insurance”, in case they are not getting enough from their diet. I came across an article online that discussed new evidence which suggests that multivitamins may actually provide more than just nutritional insurance—they could play a role in slowing cognitive aging among older adults. Results from the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) and its sub-study, COSMOS-Mind, have revealed consistent and statistically significant cognitive benefits associated with daily multivitamin supplementation.

Dr. JoAnn Manson, Professor of Medicine at Harvard Medical School and Brigham and Women’s Hospital, recently presented new results from COSMOS. In a placebo-controlled study of 573 participants who underwent detailed, in-person cognitive testing, researchers observed a significant benefit of daily multivitamin use on memory. and a borderline benefit on global cognition.

“The benefit was the equivalent of slowing cognitive aging by about 2 years.”

Furthermore, a meta-analysis combining data from three separate COSMOS cognitive studies—involving over 5,000 non-overlapping participants—demonstrated strong and consistent improvements in both memory and overall cognitive performance among those randomized to receive a daily multivitamin. The improvements were equivalent to slowing cognitive aging by approximately two years (P < 0.001 for both outcomes). These results were published in the American Journal of Clinical Nutrition and reflect a collaboration between Brigham and Women’s Hospital, Massachusetts General Hospital, Columbia University and Wake Forest University. The COSMOS trials enrolled adults aged 60 and older and employed a range of cognitive assessment tools, including in-person, telephone and web-based formats.

“The COSMOS-Mind sub-study enrolled 2,262 participants aged 65 and older…”

The COSMOS-Mind sub-study enrolled 2,262 participants aged 65 and older who completed annual telephone interviews assessing memory and thinking abilities. While cocoa extract was also tested, no cognitive benefit was found for its use. In contrast, daily multivitamin supplementation resulted in higher cognitive test scores after three years compared to placebo. The effect size suggested a 1.8-year slowing of cognitive aging, reinforcing the core COSMOS findings.

“[This study] provides the first evidence from a large, randomized trial…”

According to COSMOS Co-Director Dr. Howard Sesso, “COSMOS-Mind provides the first evidence from a large, randomized trial to show that regular use of a typical daily multivitamin may improve memory and thinking abilities in older adults.”

The COSMOS trial also assessed cancer and cardiovascular endpoints. Among 10,720 participants taking a multivitamin, 518 developed total invasive cancers, compared to 535 out of 10,722 in the placebo group. This small, non-significant difference indicated that daily multivitamin use was not associated with a reduction in total invasive cancer risk.
However, multivitamin use was associated with a 38% reduction in lung cancer incidence, though no significant effects were observed for breast, colorectal, prostate, or melanoma cancers. There were also no reductions in cardiovascular disease outcomes or events and no effect among individuals with a prior history of cancer. However, multivitamin use did improve levels of several nutritional biomarkers.

“…participants who took a daily multivitamin showed signs of slower biological aging compared to those receiving placebo…”

Recent extensions of the COSMOS research have begun to explore whether multivitamin use might also influence biological aging, not just cognitive performance. In a sub-study involving around 950 participants, researchers analyzed changes in biological aging using five different epigenetic clocks—tools that estimate how quickly a person’s body is aging at the molecular level. These included both first- and second-generation clocks, along with a more advanced algorithm known as DunedinPACE, which measures the current rate of biological aging.

Across all five clocks, participants who took a daily multivitamin showed signs of slower biological aging compared to those receiving placebo. The most notable effects were seen in two second-generation measures—PCGrimAge and PCPhenoAge—which revealed a 10% to 20% reduction in the pace of aging over two years. This translates to roughly four months of aging being delayed. Interestingly, those who were biologically aging more rapidly at the start of the study seemed to benefit the most from supplementation.

These findings suggest that multivitamins might offer more than symptom-level support—they could also affect the underlying aging process itself. If confirmed in future studies, this raises the possibility that multivitamin use could be part of a broader longevity strategy, helping extend the years of life spent in good health.

These findings offer compelling evidence that multivitamins may provide a safe, affordable and accessible strategy for slowing cognitive aging, particularly in older adults who may be deficient in key micronutrients such as vitamins B12 and D, lutein and zinc.

“…multivitamins should not replace a healthy diet and lifestyle…”

While multivitamins should not replace a healthy diet and lifestyle, they may serve a complementary role in maintaining cognitive health and function. As Dr. Manson noted, “If this benefit had been observed with an expensive pharmaceutical, it would likely be marketed aggressively.”

Ongoing and future studies from COSMOS will continue to evaluate the effects of multivitamin use on various aspects of aging and disease prevention. These results will be critical for informing potential updates to clinical guidelines and public health recommendations.