Multivitamins: Is the Jury Still Out?

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by

Andre Broussard, D.C.
in

JoAnn E. Manson, MD, DrPH
April 04, 2014

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.

Launch of a New Large-Scale Trial of Multivitamins

I am quite pleased to tell you that we have recently announced the launch of a new large-scale, randomized trial of multivitamins in 18,000 participants, 12,000 of whom will be women. This will finally provide us with information about the role of multivitamins in lowering risks in women. We will look at breast cancer, other types of cancers, total cancer, cardiovascular disease, eye diseases, and a large number of chronic disease outcomes.

Now, I do want to emphasize that multivitamins are very different from the megadose, individual micronutrients. We already know that studies using high-dose beta carotene and megadoses of vitamin E did not show favorable results, and we found some added risks in these randomized trials.[4] It is quite appropriate that the US Preventive Services Task Force is advising against the use of megadoses of antioxidants and other vitamins, but that is very different from multivitamins.[4] We need to know the balance of benefits and risks.

What should we do in the interim, while awaiting results from this large-scale trial? Many people take multivitamins as an insurance policy because they are concerned about whether their diets are healthful and balanced. That is reasonable practice, but it is important to underscore that multivitamins will never be a substitute for a healthful and balanced diet. Taking a multivitamin can be a reasonable insurance policy for many people who are concerned about gaps in their diets — people in older age groups who may have absorption problems, people taking medications that could interfere with absorption, or those who have chronic medical conditions that may increase their nutrient needs.

Overall, we look forward to moving ahead with this multivitamin trial, which will begin recruitment later this year, in 2014. Thank you so much for your attention. This is JoAnn Manson.

References

  1. Yu SM, Kogan MD, Huang ZJ. Vitamin-mineral supplement use among US women, 2000. J Am Med Womens Assoc. 2003;58:157-164. Abstract
  2. Gaziano JM, Sesso HD, Christen WG, et al. Multivitamins in the prevention of cancer in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2012;308:1871-1880. Abstract
  3. Sesso HD, Christen WG, Bubes V, et al. Multivitamins in the prevention of cardiovascular disease in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2012;308:1751-1760. Abstract
  4. Fortmann SP, Burda BU, Senger CA, et al. Vitamin, Mineral, and Multivitamin Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: A Systematic Evidence Review for the U.S. Preventive Services Task Force. Evidence Report No. 108. AHRQ Publication No. 14-05199-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2013. http://www.ncbi.nlm.nih.gov/books/NBK173987/ Accessed March 28, 2014.

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