Taking a daily multivitamin may protect against memory loss in older adults, according to a trio of studies that included more than 5,000 participants.
Taken together, the three studies found that compared to a placebo, taking a daily multivitamin slowed cognitive aging by about two years, said Dr. Chirag Vyas, an instructor in investigation at Massachusetts General Hospital.
The research was part of the COSMOS trial, a much larger clinical trial that explored whether a daily multivitamin (in this case, Centrum Silver), a cocoa extract supplement or both could be protective against heart disease and cancer.
Results from the third and final study were published Thursday in The American Journal of Clinical Nutrition. In it, 573 adults ages 60 and up took either a multivitamin or a placebo every day for two years. Researchers evaluated their cognitive function in person and with a series of tests at the beginning and the end of the study. The two earlier studies, which also compared a daily multivitamin to a placebo, used either phone- or web-based tests to measure cognitive function.
Pfizer, the company that makes Centrum Silver, provided the multivitamins and the placebo pills used in the study. Mars Inc., the candy and snack company, partially funded the larger COSMOS trial. Neither company had any role in designing the trials.
The three studies reliably showed that taking a daily multivitamin can have a modest effect on preventing normal memory loss that comes with aging, said Vyas, who led the third study.
In a meta-analysis of all three, the researchers concluded the daily multivitamin benefited both global cognition — things like reasoning, attention and planning — and the ability to recall memories from day-to-day life in healthy older adults.
But it’s unclear which specific vitamins and minerals in a multivitamin are protective or how they exert their effects.
“Future studies are necessary to identify the specific micronutrients contributing most to the cognitive benefits,” Vyas said. Additional research that includes more racial and ethnic diversity is also needed, he said, as the majority of the participants were white.
As people age, the membranes surrounding neurons, or brain cells, start to deteriorate. Vitamins may be able to protect against some of that deterioration, Vyas said.
The notion that vitamins alone could protect cognitive function in older adults is plausible, but there are some caveats based on the relatively short studies, said Dr. Richard Caselli, a professor emeritus of neurology at the Mayo Clinic in Arizona.
“The amount of cognitive change that happens over the course of three years in healthy individuals who don’t have Alzheimer’s is pretty minimal,” he said.
Caselli said that while he would feel comfortable recommending a daily multivitamin to older patients, he isn’t sold that it would have a significant impact on cognitive function.
“I still maintain a bit of skepticism as far as what magnitude of impact this makes,” he said. “I’m doubtful the difference would be really big.”
Dr. Zaldy Tan, a geriatric medicine physician at the Cedars Sinai Jona Goldrich Center for Alzheimer’s and Memory Disorders in Los Angeles, said it’s most likely some patients would benefit more than others.
“Certainly a subset of people who are vitamin-deficient in their diets could benefit in general from a multivitamin and potentially from a cognitive standpoint,” Tan said. “But it’s hard to say right now if it’s the multivitamin causing the improvement or something else.”
Tan noted that a deficiency of some specific vitamins, including B12, A and E, have been tied to deteriorating cognitive health, though the evidence isn’t conclusive. Some people who have vitamin deficiencies may benefit from supplementing with vitamins, but it’s less likely that everyone in the general public would.
Caselli said that to protect against cognitive decline, it’s important that people take care of their overall health.
“A general rule of thumb is that everything that is bad for your body is bad for your brain and everything that is good for your body is good for your brain,” he said.
Caselli said he recommends people maintain their social lives and stay both mentally and physically active throughout older age. Common health conditions, including heart disease, sleep apnea and diabetes, can also impair brain health, he said. As far as taking a daily multivitamin, he said, people can go for it if they are worried they aren’t getting enough vitamins and minerals from their diets.
“Taking a multivitamin supplement is probably good for you, but we don’t know if it’s likely to have a big impact in people who have a healthy diet,” Caselli said.