Vitamin Supplements: Any Role for Heart Disease or Cancer?

JoAnn E. Manson, MD, DrPH


June 02, 2021

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital.

I'd like to talk with you about a recent draft statement from the US Preventive Services Task Force (USPSTF) on vitamins, minerals, and multivitamin supplements and prevention of cardiovascular disease and cancer. Is there a role for these micronutrient supplements?

The task force provides clear guidance that based on available research, the evidence is insufficient to recommend any of these vitamins or minerals for prevention of cardiovascular disease or cancer. But they go further. They actually have a D-recommendation against the use of high-dose beta carotene or vitamin E for the prevention of cardiovascular disease or cancer.

With high-dose beta carotene, there was an increased risk for lung cancer in smokers and some adverse signals for cardiovascular disease. With high-dose vitamin E (alpha-tocopherol) in the Physicians' Health Study II, there was an increased risk for hemorrhagic stroke, and the SELECT trial suggested an increased risk for prostate cancer.

It's unclear why the task force updated the statement for multivitamins, given that the last statement, in 2014, was very similar to the current statement, and there hasn't been an update on the evidence for multivitamins and cardiovascular disease or cancer. The previous large-scale randomized trial of multivitamins was the Physicians' Health Study II, which had a signal for a small reduction in cancer (about 8%) in the overall study population, and an 18% reduction in those age 70 and older. This trial was done in men only, and therefore the COSMOS trial, which includes both men and women, was started to see if these findings can be replicated. Those results are due out at the end of 2021. There may be additional information from that trial, which will look not only at cancer and cardiovascular disease but also at cognitive function and eye diseases such as cataracts and macular degeneration.

For vitamin D, although several randomized trials and meta-analyses suggest that there may be a reduction in cancer deaths, the task force is not recommending routine screening for vitamin D deficiency or routine supplementation among the generally healthy population.

Although the task force is recommending against the use of vitamins, minerals, and multivitamins, saying there is insufficient evidence to recommend the use of these micronutrients for prevention of heart disease or cancer, this doesn't mean that there is no role for these vitamin and mineral supplements. We know that there are certain high-risk populations where targeted use is appropriate. This includes pregnant women and women who are planning to conceive, where folic acid or prenatal vitamins are quite appropriate. The American Academy of Pediatrics recommends supplementation with vitamin D or iron in breastfed infants.

Among older adults, especially those with osteoporosis or pernicious anemia, it is important to provide supplementation (B12 in the case of pernicious anemia, and calcium and vitamin D for those with osteoporosis or bone health problems). Also, for those with malabsorption, such as Crohn's disease, celiac disease, or post–gastric bypass surgery, supplementation with vitamins and minerals can be quite helpful, as well as in the context of certain medications, such as metformin and proton pump inhibitors.

Overall, however, the recommendation is for the generally healthy population to try to get these vitamins and minerals from a healthful and balanced diet. That is how they are best absorbed in the most appropriate proportions. This also avoids megadosing, which is a very important message. Stay tuned for the COSMOS trial of multivitamins and other randomized trials that may shed further light on the role of vitamins and minerals in the prevention of chronic disease. Thank you so much for your attention. This is JoAnn Manson.

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