Many people are interested in how they can maintain their brain health, maximize their cognitive functions, and stave off dementia. We previously discussed findings from a large clinical trial named COSMOS-MIND that showed that a daily multivitamin-mineral supplement taken for three years improved cognitive function [1]. A recent meta-analysis that compiled data from COSMOS-MIND plus two additional clinical studies extended those findings by demonstrating that a daily multivitamin-mineral supplement improved overall cognitive function and episodic memory [2].
These findings are part of a larger randomized placebo-controlled clinical trial called the COSMOS (COcoa Supplement and Multivitamin Outcomes Study) which enrolled 21,442 adults over 60 years old. Participants of COSMOS were randomly assigned to one of four groups: 1) two placebos (neither multivitamin-mineral nor cocoa extract), 2) multivitamin-mineral and placebo (no cocoa extract), 3) cocoa extract and placebo (no multivitamin-mineral), and 4) both multivitamin-mineral and cocoa extract. The multivitamin-mineral supplement (Centrum Silver) containing 30 vitamins and minerals was taken once daily for three years. The cocoa extract (Mars Edge) contained 500 mg of cocoa flavanols and was also taken once daily for three years.
Within COSMOS, there were three substudies investigating the potential effects of multivitamin-mineral or cocoa extract on cognitive functions: COSMOS-MIND used annual telephone-based cognitive assessments, COSMOS-WEB used annual computer-based cognitive assessments, and COSMOS-CLINIC used in-person cognitive assessments in the clinic. Data from over 5,000 nonoverlapping participants across these three substudies were compiled for the meta-analysis. In other words, data from each participant was only entered once, even if s/he participated in more than one cognitive study. Meta-analyses methodically compile data from multiple clinical trials and combine them into a single analysis to draw an overall conclusion. Meta-analyses of clinical trials are more powerful and conclusive than results from a single study.
The meta-analysis found that the multivitamin-mineral intervention for two years resulted in a significant favorable change in overall cognitive function and episodic memory compared to placebo. The magnitude of effect of taking the multivitamin-mineral for two to three years may translate to a two-year slowing of cognitive aging compared to taking placebo.
These findings are encouraging given that previous clinical trials of individual vitamins, like vitamin C or E, have not been successful in slowing cognitive decline or improving cognitive function [3; 4]. At this time, it is not known which of the 30 vitamins and minerals are responsible for the improvements in cognitive function—and effects of vitamins/minerals are likely different for each individual. In the COSMOS-MIND study, the beneficial effect of the multivitamin-mineral on cognitive function was largest in participants with a history of cardiovascular disease, such as heart failure or ischemic attack. Based on observational studies, people with cardiovascular disease have micronutrient levels that are lower (e.g., vitamin D, vitamin K, and others) compared to those without cardiovascular disease, so the multivitamin-mineral supplement may have compensated for these deficiencies [5]. More research on multivitamins is needed, as the overall benefits in cognitive function may have been driven by people who were deficient in nutrients important for brain health. If this is proven to be the case, then people who are getting and absorbing adequate levels of nutrients from a brain-healthy diet are unlikely to benefit from these supplements. There is a strong body of evidence suggesting that a brain healthy diet, along with other lifestyle interventions such as physical activity, quality sleep, and others, can benefit the brain and reduce your risk of dementia. If you are inclined to start taking multivitamin-mineral supplements, talk to your doctor or pharmacist about possible interactions with medications you are taking—as taking multiple drugs and supplements can increase your risk for side effects and adverse interactions.
Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.
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