Researchers Report Herbal Supplements Vary Greatly

MINNEAPOLIS--Consumers who choose to take herbal products may not always be getting what they think, based on findings concerning inconsistent labeling and ingredient usage, according to researchers at the University of Minnesota who published a paper in the Oct. 27 issue of the Archives of Internal Medicine (163:2290-5, 2003) (archinte.ama-assn.org). "Patients who report use of herbs to their physicians may not be able to accurately describe the ingredients or recommended dosage because the products for the same herb may differ," according to the researchers. For their review, they compared 880 products for the 10 most commonly purchased herbs of 1998: echinacea, St. John's wort, Ginkgo biloba, garlic, saw palmetto, ginseng, goldenseal, aloe, Siberian ginseng and valerian.

Using the Professional's Handbook of Complementary and Alternative Medicines (Springhouse Publications, 1999) as a benchmark for ingredients and recommended daily dosages, researchers analyzed ingredients and recommended daily doses for each of the herbal products. Of the products evaluated, 43 percent were consistent with the benchmark for ingredients and recommended daily dosage, and 20 percent were consistent with the benchmark only for ingredients. However, 37 percent of the products were either inconsistent or label information was insufficient. Researchers concluded health care providers and consumers should carefully read labeled ingredients of the same or similar herbal products.

According to Mark Blumenthal, executive director and founder of the American Botanical Council (ABC), federal law does not currently require dosage ranges for herbal products. "Since herbs sold as dietary supplements are legally considered foods, there is often little or no need to require specific levels of intake, at least with many particular herbs," Blumenthal said. He said official monographs for herbs that have dosages and dosage ranges (such as those set by the German Commission E) exist based on published clinical trials and clinical use by physicians. However, even these official monographs often qualify dosage recommendations with "or equivalent preparations" because, while a dose recommendation may be based on one type of preparation, other dosage forms could also be appropriate.

Blumenthal also questioned the authors' use of the Professional's Handbook as a benchmark. He said, "With no disrespect to the authors or publisher, as far as we have been able to determine over the past several years, we know of no herbal experts who consider this publication to be authoritative or reliable. ... [M]any of the conclusions of this paper may not be credible or warranted in so far as they are based on a `benchmark' of dubious reliability."