Posted 8 February 2018
Dietary supplementation is approximately a $30 billion industry in the United States, with more than 90 000 products on the market. In recent national surveys, 52% of US adults reported use of at least 1 supplement product, and 10% reported use of at least 4 such products.1 Vitamins and minerals are among the most popular supplements and are taken by 48% and 39% of adults, respectively, typically to maintain health and prevent disease.
Despite this enthusiasm, most randomized clinical trials of vitamin and mineral supplements have not demonstrated clear benefits for primary or secondary prevention of chronic diseases not related to nutritional deficiency. Indeed, some trials suggest that micronutrient supplementation in amounts that exceed the recommended dietary allowance (RDA)—eg, high doses of beta carotene, folic acid, vitamin E, or selenium—may have harmful effects, including increased mortality, cancer, and hemorrhagic stroke.2
In this Viewpoint, we provide information to help clinicians address frequently asked questions about micronutrient supplements from patients, as well as promote appropriate use and curb inappropriate use of such supplements among generally healthy individuals. Importantly, clinicians should counsel their patients that such supplementation is not a substitute for a healthful and balanced diet and, in most cases, provides little if any benefit beyond that conferred by such a diet.
Clinicians should also highlight the many advantages of obtaining vitamins and minerals from food instead of from supplements. Micronutrients in food are typically better absorbed by the body and are associated with fewer potential adverse effects.2,3 A healthful diet provides an array of nutritionally important substances in biologically optimal ratios as opposed to isolated compounds in highly concentrated form. Indeed, research shows that positive health outcomes are more strongly related to dietary patterns and specific food types than to individual micronutrient or nutrient intakes.3
Although routine micronutrient supplementation is not recommended for the general population, targeted supplementation may be warranted in high-risk groups for whom nutritional requirements may not be met through diet alone, including people at certain life stages and those with specific risk factors (discussed in the next 3 sections and in the Box).
Continue reading at JAMA