The market for dietary supplements in the USA was estimated as about 11.8 billion dollars in 1997 with a growth rate of 10–14 % projected in the next 3 years. Data from the Food and Drug Administration collected in 1995 indicate that over 55 % of adults surveyed used some type of dietary supplement. The marketing of dietary supplements in the USA has been essentially deregulated by the passage of the Dietary Supplement Health and Education Act of 1994 (DSHEA). This legislation defined dietary supplements, made manufacturers responsible for the safety of supplements and allowed certain statements of nutrition support to be made on supplement labels. The US Congress in passing the DSHEA indicated that supplements should be available on the market so that consumers could make decisions about their use for themselves and their families. Unfortunately, information about the research base for supplement claims is not readily accessible to health professionals and consumers. There is a need for authoritative reviews of the data underlying supplement claims to assist public health professionals in their role of providing advice to the public about dietary supplements.