Multivitamins: Is the Jury Still Out?

Hello. This is Dr. JoAnn Manson, Professor of Medicine at Harvard Medical School and Brigham and Women's Hospital in Boston. Today I want to talk about multivitamins. Is the jury still out? Should we be recommending multivitamins for our patients? Do we know who is a good candidate and who is not?

It would be an understatement to say that there is a lot of confusion out there about multivitamins. This is surprising given the high prevalence of use of multivitamins. In the United States among women overall, more than one third use multivitamins; and among mid-life and older women, more than 50% use multivitamins.^[1] Thus, it is very important that we understand the balance -- the benefits and risks -- of the use of multivitamins. It is surprising that in the year 2014, there has not been a single completed large-scale randomized trial of multivitamins that includes women. I am talking about the full comprehensive multivitamins that contain at least 20 vitamins and minerals in the usual doses that would be achievable through diet. I am not talking about megadoses of individual, isolated micronutrients.

The one randomized trial that has been completed was the US Physicians Health Study-II,^[2,3] which included only men but suggested some benefits. The Physicians Health Study-II showed a modest (about 8%) reduction in cancer with use of a daily multivitamin, which could translate into quite a few cases of cancer prevented.^[2] Among the men who were aged 70 years and older, there was a statistically significant 18% reduction in cancer.^[2] The study also found about a 10% reduction in cataract risk and 10% reduction in cardiovascular disease.^[3] Findings suggested that the older men might do better than the younger men with multivitamin use. Overall results favored multivitamin use in men, but it is important to understand whether women may also benefit.

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