Echinacea: Interpreting the Evidence

Is a new article in this week’s New England Journal of Medicine the final nail in Echinacea’s coffin? Some say, emphatically, yes, and would like to use this opportunity to quash CAM research.


The Background: Echinacea (commonly known as the purple coneflower) has been touted for centuries as an anti-viral (specifically anti-upper respiratory infection) panacea. Some recommend it as a preventive measure, some as a remedy to lessen cold symptoms when taken at the first sign of illness.

Supporters of an NCCAM-funded, multi-center study of Echinacea’s efficacy say that, once-and-for-all, the debate is over. The authors conclude, “The results of this study indicate that extracts of E. angustifolia root, either alone or in combination, do not have clinically significant effects on infection with a rhinovirus or on the clinical illness that results from it.” Following the much-heralded publication of previous anti-herbal trials, some nay-sayers would like to end national funding of much-needed CAM research.

Dr. Wallace Sampson, emeritus clinical professor of medicine at Stanford University School of Medicine, and noted anti-CAM spokesperson, wrote a special editorial for the NEJM to sidecar with the Echinacea article. How timely. His conclusion: “It is time for reassessment. First, there is an answer to the question, ‘Why are we doing randomized clinical trials of folkway uses of herbs and sectarian remedies?’ The answer is that proponents and evaluators have excluded plausibility from the equation. What is needed is knowledge-based medicine, with randomized clinical trials of treatments with histories that indicate some reasonable chance of efficacy. This approach mandates a medicine based on evidence that has passed through the sieve of plausibility and that is consistent with basic sciences, other applied sciences, and history — all molded by wisdom and common sense. NCCAM, if it is to justify its existence, must consider halting its search for active remedies through clinical trials of treatments of low plausibility. A wealth of information also awaits discovery in the psychology of personal beliefs in irrational proposals, in the study of erroneous thinking, and in the study of the mechanisms behind errant social–medical trends such as the alternative-medicine movement.”

I suppose Dr. Sampson would argue that I am one of those “advocates” who “often dismiss disproof.” Not so, but I am not sold on the use of strict evidence-based medicine for the study of CAM therapies (see prior post: Burden of Proof). Interestingly, NCCAM itself only this week published a series of new fact sheets, titled “Herbs-at-a-Glance,” including one on Echinacea. I guess the jury is still out.

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