Vitamin and mineral supplements don't improve mortality

- Jennifer Middleton, MD, MPH

A recent systematic review of "Supplemental Vitamins and Minerals for CVD Prevention and Treatment" has been making the rounds in the lay press for the last week; perhaps your patients have mentioned it to you as several of mine have. Sales of vitamin and mineral supplements have only increased since 2010 in the United States, with an estimated 36 billion dollars spent by consumers on these products in 2017. Perhaps this new systematic review will convince at least some of our patients to save their money, as most supplements were not found to improve CVD outcomes, and none improved overall mortality.

The authors included 179 randomized controlled trials in their final analysis; no vitamin or mineral supplement improved overall mortality. Folic acid use did correlate with decreased cardiovascular disease (CVD) risk, and folic acid and B-vitamin supplementation correlated with decreased stroke risk; the number needed to treat (NNT) for folic acid to prevent 1 CVD event was 167, the NNT for folic acid to prevent 1 stroke was 111, and the NNT for B-vitamin complex vitamins to prevent 1 stroke was 250. Use of multivitamins, vitamin C, vitamin D, beta-carotene, calcium, and selenium did not correlate with any change in mortality. Unfortunately, antioxidant products and niacin (when taken with a statin) did correlate with an increase in total mortality; the number needed to harm (NNH) for antioxidant supplements to cause 1 death was 250, and the NNH for slow-release niacin when taken with a statin was 200.

Dr. Lin wrote earlier this year for the blog, and in print for AFP, that vitamin D screening and supplementation is an ineffective use for finite healthcare dollars. Calcium supplements have not been found to improve outcomes related to osteoporosis, but they have been linked to an increase in CVD deaths. The Choosing Wisely campaign advocates against taking a "multivitamin, vitamin E, or beta-carotene to prevent cardiovascular disease or cancer."

Certainly, in specific situations, some vitamin and mineral supplements are useful. Iron and vitamin B12 deficiencies, when identified, are reasonable to treat. Calcium supplementation may improve premenstrual syndrome symptoms. Vitamin B6 is a safe and effective treatment for nausea and vomiting in pregnancy. In each of these scenarios, however, supplementation is only useful once a clinical problem has been identified. The systematic review mentioned above reinforces that empiric vitamin and/or mineral supplementation is unlikely to be beneficial for our patients - and may even be harmful.

Vitamin and mineral supplements can't take the place of consuming a healthy, nutrient-rich diet, and the United States Preventive Task Force (USPSTF) even has a B recommendation regarding the benefit of such counseling "to promote a healthful diet." There's an AFP By Topic on Nutrition if you'd like to read more, which includes several useful patient information resources.