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TB 156
School of Medicine
University of California, Davis
One Shields Avenue
Davis, CA 95616
E-mail: chhalsted{at}ucdavis.edu
The ever-increasing public demand for herbal ingredients in dietary supplements is woefully matched against the paucity of medical practitioners’ knowledge of these products, many of which are used as drug substitutes. Given the present lack of adequate regulation of herbal products in the United States, it is imperative that practitioners be given accurate information with which to advise their patients and to avoid opposing the Hippocratic dictum, "Above all, do no harm." To fill this void, many practical books are rapidly appearing in the physician’s marketplace, each claiming authority over a vast and growing subject. Unfortunately, the qualities of the available books are highly variable, and some are thinly disguised promotional apologia for the herbal industry and are replete with misleading information.
The just-published American Botanical Council’s ABC Clinical Guide to Herbs is the latest compendium to claim authority in the field. As stated in the preface, the American Botanical Council uses "science based and traditional information to promote the responsible use of herbal medicine." The introduction by editor Mark Blumenthal points out that surveys have shown that about one-fourth of the US population uses herbal products frequently, and that 60% of users do not inform their physicians about their herbal use, nor do their physicians ask. Perhaps more alarming, herbals are used by 16% of the Americans who also use prescription drugs, which raises the specter of multiple and potentially harmful herb-drug interactions.
The stated purpose of this book is the education of health care professionals, including dietitians, nurses, and physicians, in this poorly understood facet of medicine. In particular, the editor, who is the executive director of the American Botanical Council and an adjunct professor at the University of Texas College of Pharmacy, wishes to educate health care providers in the clinical pharmacology, relative safety, and potential applications of commonly used herbs.
The introduction provides a useful background on the history of herbal use in North America. This includes the ways in which many present-day Food and Drug Administration (FDA)-approved drugs, such as dilantin, colchicines, ephedrine, and reserpine, were once widely used in their herbal form. There is also a useful discussion of the complexities of the Dietary Supplement Health and Education Act (DSHEA) and a description of the ways in which herbs are now regulated in many other countries. Here Blumenthal describes the important German Commission E, which produced critical monographs on 380 different herbs between 1978 and 1995. These monographs form the basis of the German government’s regulation of herbals according to usual pharmaceutical standards, and many of them are available in a paperback book edited by Blumenthal and published previously by the American Botanical Council (1).
The 389-page body of the present book consists of "clinical overviews" of 29 herbs arranged alphabetically from bilberry to valerian. The criteria for inclusion of an herb in this book include the herb’s popularity as measured by its position in retail sales in 1999, with the implication that those herbs with the greatest sales would be most likely to be discussed in a patient interview. Examples from the list are black cohosh, echinacea, ephedra, evening primrose oil, garlic, ginkgo, ginseng, kava, saw palmetto, and St John’s wort. The chapter on each selected herb is divided into a brief overview, general description, primary and potential uses, dosage of crude and standardized preparations, pharmacologic actions, mechanisms of action, contraindications, adverse effects, drug interactions, safety rating by the American Herbal Products Association, regulatory status, a clinical review, a list of brands, and a reasonably comprehensive list of references. This information is followed by a table that summarizes selected published clinical studies on each selected herb. The appendix of the book includes a comprehensive listing of commercial products and their sources, alphabetized by the name of the herb. This is followed by contact information for the different manufacturers and distributors and an interesting table of the top-selling herbs in the United States for the year ending October 2002.
The principal question one must ask in evaluating any book on herbal products is whether it is objective and unbiased—ie, whether it presents sufficient information on both the efficacy and safety of each selected herb. The scorecard is mixed for this book. On the positive side, the tables and references to clinical trials are mostly comprehensive, and they include a useful update on recent studies through October 2002, with thorough referencing. Yet, whereas the author typically presents the pros and cons on the safety of each herb, too often the opposing arguments are minimized or criticized rather than dispassionately evaluated. In other words, the imbalance of the book leans toward the claims of the herbal industry rather than toward providing to the practitioner or other reader clear scientific evidence for the safety and efficacy of each selected herb.
For example, the chapter on kava includes details of clinical trials on its efficacy in reducing anxiety and its lack of effect in improving mental function. However, the reader must scrutinize the text to learn that there have been at least 30 reported cases of hepatoxicity due to kava usage, including at least 5 cases of liver failure, at the time of the book’s publication. Implausibly, the editor suggests that the "ethanol solutions" of kava could explain the incidences of liver toxicity. A current review of PubMed identifies at least 40 entries on the topic of kava and the liver, including a bulletin from the Centers for Disease Control and Prevention in late 2002 that included descriptions of 11 cases of fulminant liver failure requiring liver transplantation, an FDA health advisory, and the statement that kava use has been restricted by Canada, Australia, France, Switzerland, and Germany (2). A more recent report, unavailable to the editor at the time of book publication, included 9 additional cases of kava-associated fulminant failure; 2 of these patients died, and 8 underwent a liver transplant (3). Most of the reported cases of liver failure were idiosyncratic, occurred with regular dosages of kava, did not involve other drugs such as ethanol, and appeared without evidence of preexisting liver disease. Nevertheless, the chapter concludes with an extensive excerpt from another report, which states that kava "has no scientifically established potential for causing liver disease." As is the case for all the chapters, in the chapter on kava, the sections on chemistry and pharmacologic actions do not discuss metabolic processes that might elucidate potential causes of toxicity of this herb.
The chapter on ephedra cites several studies showing that weight loss can be achieved by well-supervised and controlled dosage (4) and addresses the extensive evidence for risk of hypertension, arrhythmias, stroke, and sudden death. The chapter cites an exhaustive survey of 140 reports of adverse events, including 10 deaths, and concludes that 31% were definitely or probably related to ephedra alkaloids (5), but the editor also cites other opinions that associations do not prove causation and that the incidences of serious side effects may not be greater than those found in the general population. Whereas the editor concludes that ephedra risks are minimal to nonexistent if the herb is used in proper dosage, he fails to cite a 2000 evaluation of the content of 20 different ephedra-containing supplements that showed frequent lot-to-lot variations as great as 10-fold (6). Last year, an evidentiary RAND Corporation report commissioned by the NIH Office of Dietary Supplements concluded that short-term ephedrine use is associated with modest weight loss, but also that the use of ephedrine- or ephedra-containing supplements increases the risks of nausea, hyperactivity, and palpitations by at least 2-fold and has accounted for at least 5 documented deaths, 5 myocardial infarctions, 11 cerebrovascular accidents, and 8 cases of psychiatric illness (7). The FDA issued an alert on December 30, 2003, that advised consumers to stop purchasing and using all products that contain ephedra.
Overall, this book contains a vast amount of potentially useful information but fails to present a balanced perspective on the benefits and the risks of the most commonly used herbals. It is troubling that many of the 29 listed underwriters of this project of the American Botanical Council, grouped as "visionaries, partners, supporters, and friends, " are either manufacturers or promoters of the very same herbal products described in detail in the book. Indeed, the stated purpose of the American Botanical Council, to "promote the responsible use of herbal medicine," belies a bias. The scientific practice of medicine should not be based on promotion of any class of potentially therapeutic agents but instead on the use of agents that are rigorously scrutinized as to their safety and efficacy. Whereas it is true that many herbs provided the historical basis for modern pharmacology, that cannot be used as a basis for assuming that herbals are inherently as efficacious or as safe as FDA-regulated drugs. Why should organ failure and death be accepted as a potential complication of an herbal product, when such events typically result in the withdrawal of FDA-approved drugs from the marketplace? For example, both ephedra and fenfluoramine have been shown in clinical trials to result in weight loss; therefore, should not the same standards of nonacceptance of a mortality hazard that resulted in the withdrawal of fenfluoramine from the market also be applied to ephedra? Until the same rigorous standards for the acceptance of pharmaceutical agents for therapeutic use are applied to herbal products, it is difficult to accept as scientific any discussion of their benefits and hazards. Unfortunately, this book comes across more as an apologia for its herbal industry sponsors than as the dispassionate critique of potential benefits and risks of herbal products that is sorely needed by health care professionals and the public alike.
ACKNOWLEDGMENTS
The author has no financial or intellectual conflict of interest with regard to the book reviewed, and he takes full public responsibility for the content of this review.
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