A new study reported that adults 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 nutritional supplement might actually benefit healthy people.

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

But experts not involved in the trial cautioned that the benefits were small, and it was not clear that they would translate to tangible improvements in people’s lives.

“I would put it in the realm of promising, but I wouldn’t go to the bank with it,” said Mary Butler, an associate professor of public health at the University of Minnesota who has published several papers evaluating interventions to prevent dementia.