Researchers at Brigham and Women’s Hospital and Harvard Medical School reported last month that a randomized trial of the humble multivitamin found surprisingly potent effects on memory as we age. The COSMOS-Web Study showed that, among 3,500 subjects 60 and older, a daily multivitamin led to 3.1 years less cognitive aging than for those assigned a placebo. The clinical study was the second cognition trial in COSMOS to suggest that multivitamins can slow memory loss.
Published in the American Journal of Clinical Nutrition, the study was co-led by JoAnn Manson, chief of Brigham’s Division of Preventive Medicine, the Michael and Lee Bell Professor of Women’s Health at the Medical School, and professor of epidemiology at the Harvard T.H. Chan School of Public Health, and Howard Sesso, associate director of the Division of Preventive Medicine, an associate professor at the Medical School, and a Chan School epidemiologist. We talked to Manson about the findings. The interview has been edited for clarity and length.
GAZETTE: You found an overall cognitive improvement equivalent to 3.1 years in age-related decline. Can you explain what that means?
MANSON: We saw better performance on memory tests among the participants randomized to multivitamins compared to those assigned to placebo. The benefit was apparent at one year and was sustained over the three years of the trial. Although an initial improvement in memory was seen, possibly due to replenishing of micronutrients in those with deficiencies, the longer-term effect was slowing of age-related memory loss and cognitive aging.
GAZETTE: You saw no continued improvement over years two and three?
MANSON: The benefit compared to the placebo group was sustained for the three years of the trial, but the amount of benefit plateaued after one year. It remains to be seen whether taking multivitamins for five or 10 years would confer a greater benefit than taking them for three years. I think we need longer trials and trials starting in midlife.
GAZETTE: This is the second COSMOS trial — after COSMOS-Mind, released in 2022 — to find a memory benefit from multivitamins. What’s your takeaway?
MANSON: The fact that two separate randomized trials with different methodologies showed statistically significant benefits of multivitamins compared to placebo is remarkable. There haven’t been other randomized trials of multivitamins — containing all the essential vitamins and minerals — where cognition and memory were rigorously tested and with a baseline assessment of cognition before treatment began. Other randomized trials have generally tested just one or a few of these micronutrients, not a multivitamin with more than 20 essential vitamins and minerals.
GAZETTE: Is this an indication that when considering supplements, we should think of these nutrients together as opposed to searching for one thing that is key to maintaining memory as we age?
MANSON: Yes, it’s unlikely that a single nutrient is a magic bullet. Several micronutrients are known to be important for optimal brain health, and a deficiency of one or more of those essential vitamins and minerals could accelerate cognitive aging. Some people may have a deficiency in one and others may have a deficiency in another. So, taking a multivitamin containing more than 20 of these micronutrients will tend to benefit more people than taking a single isolated micronutrient which would benefit only those people who are deficient in that one micronutrient. It doesn’t mean that every single ingredient in the multivitamin is a major contributor to these benefits. It’s possible it was only a few of the vitamins and minerals. Some of the top candidates are vitamin B12, other B vitamins, vitamin D, lutein, zinc, and magnesium.