This transcript has been edited for clarity.
This is Dr. JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women’s Hospital. , known as COSMOS (Cocoa Supplement and Multivitamins Outcome Study). This is the second COSMOS trial to show a benefit of multivitamins on memory and cognition. This trial involved a collaboration between Brigham and Columbia University and was published in the American Journal of Clinical Nutrition. I’d like to acknowledge that I am a coauthor of this study, together with Dr. Howard Sesso, who co-leads the main COSMOS trial with me.
Preserving memory and cognitive function is of critical importance to older adults. Nutritional interventions play an important role because we know the brain requires several nutrients for optimal health, and deficiencies in one or more of these nutrients may accelerate cognitive decline. Some of the micronutrients that are known to be important for brain health include vitamin B12, thiamin, other B vitamins, lutein, magnesium, and zinc, among others.
The current trial included 3,500 participants aged 60 or older, looking at performance on a web-based memory test. The multivitamin group did significantly better than the placebo group on memory tests and word recall, a finding that was estimated as the equivalent of slowing age-related memory loss by about 3 years. The benefit was first seen at 1 year and was sustained across the 3 years of the trial.
Intriguingly, in both COSMOS and COSMOS-Web, and the earlier COSMOS-Mind study, which was done in collaboration with Wake Forest, the participants with a history of cardiovascular disease showed the greatest benefits from multivitamins, perhaps due to lower nutrient status. But the basis for this finding needs to be explored further.
A few important caveats need to be emphasized. First, multivitamins and other dietary supplements will never be a substitute for a healthy diet and healthy lifestyle and should not distract from those goals. But multivitamins may have a role as a complementary strategy. Another caveat is that the randomized trials tested recommended dietary allowances and not megadoses of these micronutrients. In fact, randomized trials of high doses of isolated micronutrients have not clearly shown cognitive benefits, and this suggests that more is not necessarily better and may be worse. High doses also may be associated with toxicity, or they may interfere with absorption or bioavailability of other nutrients.
In COSMOS, over the average 3.6 years of follow-up and in the earlier Physicians’ Health Study II, over 1 year of supplementation, multivitamins were found to be safe without any clear risks or safety concerns. A further caveat is that although Centrum Silver was tested in this trial, we would not expect that this is a brand-specific benefit, and other high-quality multivitamin brands would be expected to confer similar benefits. Of course, it’s important to check bottles for quality-control documentation such as the seals of the U.S. Pharmacopeia, National Science Foundation, ConsumerLab.com, and other auditors.
Overall, the finding that a daily multivitamin improved memory and slowed cognitive decline in two separate COSMOS randomized trials is exciting, suggesting that multivitamin supplementation holds promise as a safe, accessible, and affordable approach to protecting cognitive health in older adults. Further research will be needed to understand who is most likely to benefit and the biological mechanisms involved. Expert committees will have to look at the research and decide whether any changes in guidelines are indicated in the future.
Dr. Manson is Professor of Medicine and the Michael and Lee Bell Professor of Women’s Health, Harvard Medical School and director of the Division of Preventive Medicine, Brigham and Women’s Hospital, both in Boston. She reported receiving funding/donations from Mars Symbioscience.
A version of this article first appeared on Medscape.com.