From the website of the Office of Dietary Supplements, part of NIH (http://www.ods.od.nih.gov):
“One of the purposes in creating the ODS [Office of Dietary Supplements] was to promote scientific research in the area of dietary supplements. Dietary supplements can have an impact on the prevention of disease and on the maintenance of health. In the US, these ingredients are usually defined as including plant extracts, enzymes, vitamins, minerals, amino acids, and hormonal products that are available without prescription and are consumed in addition to the regular diet. Although vitamin and mineral supplements have been available for decades, their health effects have been the subject of detailed scientific research only within the last 15–20 years. It is important to expand this research to include the health effects of other bioactive factors consumed as supplements to promote health and prevent disease.
“Considerable research on the effects of botanical and herbal dietary supplements has been conducted in Asia and Europe where plant products have a long tradition of use. The overwhelming majority of these supplements, however, have not been studied using modern scientific techniques. Nor have they been extensively studied in population groups that may be at risk for chronic diseases.
“For many reasons, therefore, it is important to enhance research efforts to determine the benefits and risks of dietary supplements.”