This study alone isn’t enough to suggest routine use of multivitamins for people of all ages. It may turn out that the benefits for older adults seen in this study were due to deficiencies in certain nutrients among some of the study participants. We don’t know if this is true because it wasn’t part of the study.
Or we might learn that the benefits reported here are too small to make much difference in real life, or wane over time, or have no effect on preventing common types of dementia. And it’s hard to ignore an earlier randomized, placebo-controlled trial that was actually larger and longer-term: it found no improvement in brain function among male physicians ages 65 and older taking multivitamins.
But it does mean that more study is warranted. We need to understand who is most likely to benefit from multivitamin use, what dose is optimal, and what parts of the multivitamin are most important. We also need trials that are larger, last longer, and include a more diverse group of participants. And certainly, there's a difference between improving cognitive function and preventing dementia. We still need to know if conditions like Alzheimer’s disease can be prevented by multivitamin use or other supplements.
The bottom line
Claims that certain supplements can improve brain health are everywhere you look. But sound scientific evidence backing up those claims is much rarer. That’s one reason this new study is important: if confirmed, it means that a safe, widely available, and inexpensive vitamin supplement could improve quality of life for many millions of aging people.
In the past, claims made by the makers of various supplements and vitamins have gotten far ahead of the science. Studies like this one should help science catch up and sort out which claims are valid.
(Robert H. Shmerling, MD, is a senior faculty editor and an editorial advisory board member for Harvard Health Publishing.)