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.