Dietary supplement use by American women: challenges in assessing patterns of use, motives and costs.

The 1994 passage of Public Law 103-417, the Dietary Supplement and Health Education Act, resulted in an exponential increase in the number and variety of dietary supplements available for over-the-counter purchase. Surveys conducted on random samples of U.S. residents have shown that approximately half of all American women use dietary supplements regularly, but very little is known about the risks and benefits of long-term and widespread supplement use. To accurately evaluate the health effects of supplement use, it is important to characterize usage patterns, motivations and costs of supplement use. However, this is a considerable challenge because accurate supplement data are difficult to collect, product databases with consistent and reliable information are lacking and survey instruments or interview protocols currently in use may not capture information about product selection for specific health conditions, motivations for use, or out-of-pocket expenditures. Future research would benefit from collaborative efforts among governmental scientists, academic scientists and industry to improve dietary supplement data collection methods and develop appropriate tools for analysis.