Multivitamin and Mineral Supplementation: No Long-Term Harm

More than half of Americans take multivitamin/mineral (MVM) supplements containing more than 9 micronutrients (vitamins/minerals) that provide 100% of the recommended daily allowances (RDA). We know that vitamin supplementation has corrected some widespread deficiencies. We rarely see children with rickets any longer because we fortify foods with vitamin D, and in pregnant women, MVM that contain iron and folic acid have improved birth outcome and reduced low birth weights and rates of miscarriage.

Are MVM's safe over the long-term? That's the question that researchers from the University of Hohenheim in Germany pursued with a systematic review of MVM use for 10 years or more. Their findings, published in the January 2017 issue of the journal Nutrition, indicate there is ample evidence of long-term safety.

As noted, MVM use is common in the general population. Regardless, many patients fail to consume the RDA for several vitamins and minerals even with MVM supplementation: vitamin D, vitamin E, magnesium, calcium, vitamin A, and vitamin C 31%.

Recent meta-analyses support supplementation with a MVM rather than just folate and iron alone in pregnant women. Infants born to pregnant women who took a prenatal formula MVM had a lower incidence of malformations and better birth weights than those born to women who took just iron and folate.

Among the recommendations noted in this study that are helpful to pharmacists who field questions about MVM:

• Advise young women who are vegetarians or vegans to take an MVM daily for several months before they contemplate pregnancy.
• Elderly people who consume fewer than 1600 kcal/d—a situation that is more common in patients older than 75 years—need MVM supplementations.
• Elderly people often develop vitamin B₁₂ and vitamin D deficiency, and these should be added as free-standing supplements.
• Obese individuals undergoing malabsorptive bariatric surgery need MVM supplementation to correct or prevent further deficiencies.

The studies reviewed found that most people tolerated MVMs well, with only minor nonspecific gastrointestinal symptoms and similar mild adverse effects reported.

The researchers stress that taking MVMs within the RDA range will not result in excess intake, even when including the impact of food and fortified food, nor does it increase mortality.

Reference

Biesalski HK, Tinz J. Multivitamin/mineral supplements: Rationale and safety - A systematic review. Nutrition. 2017;33:76-82.