Letters to the Editor

Definitive Statements Should Only Be Made with Evidence


Am Fam Physician. 2004 Oct 15;70(8):1448-1451.

to the editor: I found the final comments of the article “Black Cohosh,”1 to be paradoxical and not what I would expect to be accepted by any medical journal. The authors states: “Although the clinical trials on black cohosh are of insufficient quality to support definitive statements, this herbal medicine does appear to be effective in the short-term treatment of menopausal symptoms.”1 One has to question how he can make this statement with authority if there are no studies that support this conclusion. The author admits that the studies2 he cites from Germany are based on case reports and are not randomized controlled studies. Therefore, he provides no definitive proof that black cohosh alleviates menopausal symptoms.

I believe this is another unfortunate example of giving various herbal or over-the-counter products more slack in their scientific study. If this had been a large, controlled study of a medication for heart disease that found no evidence of efficacy, we would not make assumptions that it is effective in the short-term treatment of symptoms. The author’s conclusion that black cohosh appears effective in the short-term treatment of menopausal symptoms is just biased speculation and not a scientific conclusion.

I fear that physicians and researchers are drifting backward into testimonials to make their clinical decisions. I think we have to hold natural products to the same standards that we hold every other agent, and we should not let statements like this one go unchallenged. The problem with such statements is that they are repeated by those who wish to promote these products. If a journal such as American Family Physician prints a statement like this in a reviewed article, it suggests that the journal is in agreement with these conclusions. I think this is sloppy science and sloppy medicine.


1. Kligler B. Black cohosh Am Fam Physician. 2003;68:114–6.

2. Blumenthal M. German Federal Institute for Drugs and Medical Devices. Commission E. The Complete German Commission E monographs: therapeutic guide to herbal medicines. Austin, Tex.: American Botanical Council, 1998.

in reply:Dr. Bonde makes an important point regarding the difficulty of making clinical decisions regarding herbal products given the frequent lack of definitive evidence from clinical trials. Although the conclusions in my review article on black cohosh1 were based on small clinical trials (not case reports, as Dr. Bonde states), the fact remains that more research on black cohosh is needed. Unfortunately, the large, randomized, double-blind controlled trials that are performed on new medications rarely are done for herbal products. This is partially because the financing for these trials, which often comes from pharmaceutical companies that are motivated by the profit potential of a new medication, is not available for the generally nonpatentable botanical products. Nevertheless, the evidence for the efficacy of black cohosh for menopausal symptoms was sufficient for the American College of Obstetricians and Gynecologists to recommend its use.2

An important question raised by Dr. Bonde is whether the standard of evidence of efficacy required should be uniform for all treatments, or whether this standard should be flexible depending on the safety margin of the treatment under discussion. Clearly, the standard of evidence of safety must be uniform. An herbal product known to have significant adverse effect potential should be used as cautiously as a medication or surgical procedure known to have such potential. But, when the safety margin is wide, as it clearly is with black cohosh, some would argue that we should tolerate a somewhat softer standard of evidence of efficacy in our clinical decision-making analysis of risk versus benefit.3 In fact, such a standard already is tolerated for many over-the-counter medications. For products with an adverse effect potential that is higher, the strictest standards of evidence of efficacy should be used. This is a challenging question in this age of evidence-based medicine, but it is a question worthy of discussion as we move forward in our understanding of how to incorporate the use of natural medicines into our work with patients.


1. Kligler B. Black cohosh. Am Fam Physician. 2003;68:114–6.

2. American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Gynecology. ACOG Practice Bulletin. Clinical Management Guidelines for Obstetrician-Gynecologists. Use of botanicals for management of menopausal symptoms. Obstet Gynecol. 2001;97:1–11.

3. Lee RA. Botanical medicine. In: Kligler B, Lee RA, eds. Integrative medicine: principles for practice. New York: McGraw-Hill, 2004.

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This series is coordinated by Kenny Lin, MD, MPH, Associate Deputy Editor for AFP Online.



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