Multivitamins have long been controversial. Studies exploring what, if any, benefit they provide for overall health have been mixed; some show a slight benefit in lowering the risk of cancer and other diseases, while others show that vitamins don’t do much for keeping the heart and brain healthy. Some experts dismiss them as good for little else than making expensive urine.
But in the latest study published in the American Journal of Clinical Nutrition, a group of scientists from Harvard Medical School and Columbia University report that a daily multivitamin can improve memory and even slow some of the cognitive decline that comes with aging. And it didn’t take massive doses of vitamins or special formulations. In the trial, participants took the brand Centrum Silver, sold in nearly every supermarket and pharmacy around the country.
Along with a grant from the National Institutes of Health, the study was financially supported by Mars Edge, which provided the technology infrastructure for the web-based cognitive evaluations, and Pfizer Consumer Healthcare (now Haleon), the maker of Centrum Silver, which provided the multivitamin and placebo pills. Neither company was involved with collecting or analyzing the data, according to the study authors.
In the trial, 3,500 people over age 60 were randomly assigned to take a daily multivitamin or a placebo for three years. The researchers then evaluated their brain function after the first year and again two years later, then compared those results to assessments they took at the start of the study.
Overall, people who had taken a multivitamin every day for a year showed greater improvement in their ability to immediately recall items in a web-based test compared to before they began taking the vitamins. The improvement was greater than that among people taking placebo. These benefits persisted—but did not increase—over the following two years of the study.
Read More: What the Science Says About the Health Benefits of Vitamins and Supplements
The improvements did not translate to other cognitive functions, such as executive functions like reasoning and other memory skills, but an earlier study by the same group found broader cognitive benefits among 2,200 people over 60 who were randomly assigned to take a daily multivitamin for three years or a placebo.
“I think overall we are seeing benefits of multivitamins going beyond age-related memory loss into the slowing of global cognitive aging based on these two separate studies,” says Dr. JoAnn Manson, professor of medicine at Brigham and Women’s Hospital and Harvard Medical School and one of the study’s lead investigators. “We think it’s remarkable that the findings were replicated in this second trial.”
The benefit of taking a daily multivitamin for three years translated to a slowing of cognitive aging by just over three years, says Manson. The fact that the trial compared multivitamin users to those receiving placebo provides more confidence in the results, she says, and the study is only the second to analyze the effects of multivitamins on cognition in such a rigorous way. The only other previous trial, the Physicians Health Study II, did not find any difference in cognition between multivitamin and placebo takers among 14,600 physicians. But that study did not conduct cognitive tests of the participants at the start of the study to establish a baseline to which to compare the effects.
What the new study found—that multivitamins’ benefits appeared after a year of daily use, then remained consistent over the next two—suggests that the effect may not be cumulative. In the Physicians Health Study, participants were evaluated after about 2.5 years, after which any benefit may have already occurred. “We might have missed the opportunity to see any benefit because we performed the first assessments too late,” says Howard Sesso, associate professor of medicine at Brigham and Women’s Hospital, and a co-author of both the current study and the Physicians Health Study. “They might have already had improvements, and these just persisted.”
While the findings are encouraging, both Manson and Sesso say that relying solely on a multivitamin to maintain cognitive health among older people isn’t enough. “Dietary supplements are never a substitute for a healthy diet and lifestyle,” says Manson. “However, multivitamins can be a complementary approach, especially in mid-life and among older adults—some of whom start having problems absorbing nutrients and may have less than optimal diets.”
The researchers hope other groups try to replicate their findings to solidify any connection between multivitamins and cognitive health, and also generate more data into how the multivitamins may be contributing to improved memory. The group plans to continue following the participants in the study to see if the benefits persist beyond three years; they also hope to study younger people, beginning at age 50, to see if the improvements might be greater if people start taking multivitamins earlier.
“Do the results mean we should broaden public health recommendations to include daily multivitamins? I don’t think the data are there yet,” says Sesso. “We need to understand more about why and how these vitamins are working.”