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United States Department of Agriculture

Agricultural Research Service

Dietary Supplements Made from Plants
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Leslie M. Klevay

When it comes to dietary supplements, the American public does not know what it is doing and how can it? So said a well known nutrition commentator and consumer advocate at a recent open conference on dietary supplements organized by the United States Pharmacopeial Convention (USP). What the public gained in freedom when the Food and Drug Administration (FDA) was prohibited from regulating dietary supplements, it lost in protection.

The USP is a voluntary, non-profit organization creating a knowledge base on medicines which it disseminates as standards of quality and information on use to health professionals, patients and consumers. The recent USP conference emphasised supplements prepared from plants.

St. John's Wort, is an aromatic, perennial herb that often blooms around June 24, the traditional birthday of St. John the Baptist. The plant is thought by some people to be useful in the treatment of mild, mental depression. A picture of St. John's Wort in full bloom was featured on the cover of the workbook for the USP conference.

St. John's Wort, valerian, ginseng, ginkgo and saw palmetto are among the botanicals considered at the conference. These and other herbs are quite complex, containing numerous chemicals, some of which may have beneficial effects when eaten. In general when herbs are prepared for human consumption, it is desirable that preparations are of uniformly high quality. This goal may be difficult to attain as plants vary in chemical components depending on the soil, rainfall, climate, etc.

A recent issue of the New England Journal of Medicine illustrates hazards of some preparations. Articles and correspondence described how an herbal mixture with estrogen-like activity may interfere with other treatments, how contamination of a botanical dietary supplement produced an overdose from drugs ordinarily prescribed for heart failure, how self-medication with an herbal preparation resulted in lead poisoning, how patent medicines frequently are adulterated or contain undeclared pharmaceuticals, how some botanical products do not contain the ingredient described on their labels or have doses that may vary by a factor of ten from the label and how product labeling has become an art form of double-speak and insinuation. The FDA can intervene in these situations only after the fact when harm has been done.

The USP traditionally provides standards of identity, strength, quality control, purity, packaging and labeling for drugs. It has issued monographs on comfrey, feverfew, ginger, St. John's Wort and valerian. There are plans to evaluate the 30 or so products that comprise 90% of the botanical market in the U.S. With some 4000 products available, let the public beware, as no organization has the resources to test all of them.

Last Modified: 10/23/2006
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