Dietary SupplementsDietary Supplements and Health: One Part Science, Nine Parts Hype

Use of dietary supplements has much increased over recent decades; around half of people in North America regularly use supplements. A wide variety of supplements are sold. In some cases there is firm evidence supporting their efficacy but in most cases there is little or no supporting evidence. Some herbal preparations have toxic effects and should therefore only be used with much caution. Supplements are marketed by a variety of different methods, including health food stores, advertisements in newspapers and on TV, multilevel marketing, bulk mail, spam e-mails, and Internet websites. Marketing of supplements often involves giving unreliable or dishonest information that is not supported by scientific studies. The marketing of supplements in the United States is only weakly regulated.