What we know about multivitamins and memory

A new study reported that adults aged 60 and older who took a daily multivitamin for two years scored higher on memory and cognitive tests than those who took a placebo – a rare example of a clinical trial finding that a dietary supplement would actually benefit healthy people can come.

“It suggests that multivitamins may be a safe, affordable and accessible approach to protecting cognitive health in older adults,” says Dr. Chirag Vyas, a psychiatric epidemiologist at Mass General Brigham in Boston and lead author of the study, published Thursday in The American Journal of Clinical Nutrition.

But experts not involved in the trial warned that the benefits were small and it was not clear they would translate into tangible improvements in people's lives.

“I would think it's promising, but I wouldn't take it to the bank,” says Mary Butler, an associate professor of public health at the University of Minnesota who has published several papers evaluating interventions to prevent dementia.

The study was part of a larger study involving more than 21,000 older adults that looked at whether supplements can protect against several age-related diseases, called the COcoa Supplement and Multivitamin Outcomes Study (COSMOS). The new report included results from a subset of 573 participants — mostly white and relatively well-educated — who took several cognitive tests in person.

People in both the multivitamin and placebo groups improved their cognitive scores over the course of two years, possibly because they were already familiar with the tests. But the participants who took the multivitamin showed slightly greater gains, with the biggest bump coming in memory ratings.

The study also combined these findings with results from two previous COSMOS studies that tested the cognition of more than 5,000 people over the phone or online. Across the three studies, those who took multivitamins showed consistent improvements in their scores on tests of memory and overall cognitive ability compared to people who received a placebo, said Dr. JoAnn Manson, professor of medicine at Harvard University and co-coordinator of the COSMOS process.

The researchers estimated that the memory boost seen in people taking the multivitamin corresponded to a two-year reduction in brain aging, meaning they theoretically tested as well as someone two years younger, said Dr. Vyas.

Experts not involved in the study said the study was well designed: it included a large number of participants and used well-established cognitive tests. But the findings “are relatively modest,” says Dr. Hussein Yassine, associate professor of neurology at the University of Southern California Keck School of Medicine. While some people may have really benefited from the multivitamin, he said, the majority probably did not.

Dr. Yassine added that claiming a multivitamin could slow cognitive aging by two years is “really a stretch.” To reach that conclusion, the researchers compared the performance of the multivitamin group with average test scores by age. Dr. Yassine disagreed with this technique and called the interpretation 'misleading'.

That calculation was also the main concern raised by Dr. Pieter Cohen, an internist at Cambridge Health Alliance in Boston who studies supplements. He added that it was unclear whether the subtle improvements measured in people taking multivitamins were meaningful. It would be much more convincing if the study showed that people who took multivitamins were less likely to be diagnosed with Alzheimer's at a certain age, or could live independently longer, he said.

Dr. Manson agreed that more research on multivitamins is needed, especially in groups with more racial, ethnic and socioeconomic diversity. Follow-up studies should analyze who benefited from the supplements and why, added Dr. Yassine about it. For example, it's possible that the gains were driven by people who previously weren't consuming enough of certain nutrients important for brain health, such as vitamin B12, vitamin D and zinc.

“Rather than concluding that everyone should take a multivitamin, I think we should perhaps try to understand who would benefit from taking the multivitamin,” said Dr. Yassine.

Multivitamins may be helpful for certain people, such as those with conditions that affect their ability to absorb nutrients, said Dr. Cohen, but most healthy people don't need one. “I'm not going to recommend multivitamins to improve memory based on this data,” he said.

The COSMOS study, funded by the National Institutes of Health and chocolate maker Mars Inc., was originally designed to see whether multivitamins or supplements containing cocoa flavonols would affect heart disease or cancer risk. But the trial found little benefit from either supplement.

Other studies have done so largely shown that multivitamins did not improve cognition or prevent dementia. For example in a trial against almost 6,000 male doctors Followed for 12 years, those who took a multivitamin performed no better on cognitive or memory tests than those who took a placebo.

However, research has consistently shown that a healthy diet and other lifestyle interventions can benefit the brain. Puja Agarwal, a nutritional epidemiologist at Rush University Medical Center in Chicago, called the new findings “encouraging.” But, she added, “if we can meet our nutritional needs with a dietary approach, that should be the first priority.”