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Am Fam Physician. 2004;69(3):493-494

to the editor: The excellent review1 of the dietary supplement valerian by Drs. Hadley and Petry will be very helpful for family physicians. However, physicians are still faced with the confusing process of determining which particular manufacturer and product of these herbal preparations to recommend to their patients.

Unfortunately, studies conducted by objective investigators have concluded that quality control standards for dietary supplements in the United States range from good to nonexistent. The most disturbing evidence comes from studies2 demonstrating the adulteration of dietary supplements with pharmaceuticals. Other studies2 have discovered products that are contaminated with heavy metals or pesticides.

Another significant problem with dietary supplements in the United States is the substantial discrepancies between the labeled contents and the actual amounts found in the dosage units. Such inaccuracies have been demonstrated for many dietary supplements,2 including valerian.3 In addition, supplement content, even from the same manufacturer, can vary widely from lot to lot.2

This information illustrates an apparent lack of interest in product quality by many dietary supplement manufacturers or, in the worst cases, fraudulent behavior. In either case, the prevalence of low-quality products increases the risks of ineffective supplements or adverse reactions to supplements.

We believe that quality testing of these products is in the best interest of public safety. Only one independent group has tested valerian. In 2000, tested 17 valerian products purchased off the shelf in the United States.3 Five products listed one or more additional herbs. The products were analyzed for their total valeric acid content to determine if they possessed the type and amount of valerian stated on the label. The testing method and passing scores are available on the Web site. Only nine of the 17 products passed. Unfortunately, a 47 percent failure rate is not unusual for these products. For example, has tested over 700 brands of dietary supplements; 30 to 40 percent of the herbal products did not pass. Of the eight valerian products that failed quality testing, four had no detectable levels of the expected valeric acids, and the other four had only one half the expected or claimed amounts.

The World Health Organization4 and the American Medical Association5 have called for significant regulatory changes for dietary supplements. The U.S. Food and Drug Administration has expressed concern about the increasing incidence of adverse reactions to impure or contaminated dietary supplements and is developing plans to improve the regulation regarding both quality manufacturing practices and truth in labeling.6

We recommend that physicians writing reviews on dietary supplements guide their readers on how to find and recommend safe and high-quality dietary supplements to their patients. Under the current lack of regulatory oversight in the United States, otherwise excellent dietary supplement reviews run the risk of being less helpful to family physicians and even dangerous to our patients.

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This series is coordinated by Kenny Lin, MD, MPH, deputy editor.

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