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Is echinacea dead? Don’t believe it! A much publicized article recently featured in the New England Journal of Medicine claims to establish that echinacea has no effect in the prevention and treatment of the common cold.1 If you were to believe this article, you would be saying a premature requiem over this helpful herb. In the study, the authors compared the effect of different preparations of Echinacea angustifolia root on rhinovirus infection. The infection was artificially induced using a strain of rhinovirus type 39, which is considered safe. The dose of echinacea root used was 900 mg per day for seven days before the virus challenge and then five days after. The study evaluated both preventative and treatment effects of the various echinacea preparations on the rhinovirus infection and found no significant results for either. An important consideration was that the dose was not increased for the acute infection phase of the study. The Echinacea angustifolia root was extracted under different conditions in order to compare the effects of the different phytochemical profiles that are typically found in echinacea products. The study has been widely condemned, especially in terms of the low dose of echinacea used. To put this in perspective, the daily amount of echinacea used in the trial was only a fraction (around one fifth to one tenth) of the acute dose typically used by herbal clinicians. In defense of the dose used, Dr. Ronald Turner, one of the principal scientists involved in the trial, recently claimed, “There is no evidence from prior studies that the dose of echinacea would have changed the outcome…”.2 But in fact a study published as far back as 1992 suggests that this is not the case. In a randomized, double-blind, placebo-controlled trial, 180 patients with upper respiratory tract infections received the equivalent of 1,800 mg per day or 900 mg per day of E. purpurea root as a tincture, or placebo. Patients receiving the high dose experienced significant relief of symptoms. However, patients receiving the lower dose (900 mg) were not significantly different from the placebo control.3 Note: In the original study, the authors calculated these doses to be 900 mg and 450 mg respectively. But this is due to an error on their part. Based on their stated doses of 180 drops (9 mL) and 90 drops (4.5 mL) of a 1:5 tincture, the equivalent doses of dried root used were 1,800 mg and 900 mg. The authors of the New England Journal of Medicine study could be forgiven for not picking up on this error. However, they should have also considered the doses traditionally used by herbal clinicians. The doses recommended in professional herb texts are clearly higher than 900 mg per day for acute infections.4 As a specific example, I recommend my patients to take around 2,500 mg of root three to four times a day when they have a cold or flu. Even one of the article’s authors has acknowledged that the amount of echinacea used in the study may have been insufficient. David Gangemi, PhD, of Clemson University, responded to a question posed about this research at last month’s Medicines from the Earth Symposium in North Carolina by stating, “I think in retrospect, if we go back and we look at some of the other products that are out there maybe we're only one tenth the level we should be.”5 Another aspect of this study that limits the generalization of its results to all users of echinacea was that an artificial infection was induced in young, healthy volunteers. This could be irrelevant to the real-life situation in which people with compromised immunity are exposed to a range of constantly evolving viruses and bacteria. The authors have defended this point, stating that their model is appropriate for testing the antiviral activity of a drug. However, echinacea is thought to act on viral infections by modifying the immune response. There is no evidence to suggest that echinacea has the ability to kill viruses directly. So the model may, in fact, be inappropriate for the way echinacea works. Or it could be that the value of echinacea in acute respiratory infections is the minimization of the secondary bacterial infections that often follow, a benefit that the trial model would not have detected. Perhaps of greater concern is the way that negative clinical trials on natural treatments are readily published in major medical journals and receive huge publicity, and that many positive clinical trials rarely make it to the prestigious journals and enjoy little attention from the media. This is a form of publication bias I have experienced. A few years ago I advised for a placebo-controlled clinical trial which found that regular use of echinacea root over the winter months significantly reduced the incidence of winter infections in college students. When the authors of that study submitted their findings to a well known U.S. medical journal they were advised by the editor that the journal could not see any merit in publishing their positive clinical findings. But the same journal has since carried negative trials on several natural treatments, including echinacea. I consider echinacea to be one of the most reliable plants in our materia medica. I have no doubts over its value in the prevention of infections in general, and specifically winter infections. The judicious use of echinacea can also shorten the duration of acute infections (note the high doses mentioned above) and balance immune function in complex disorders such as asthma, chronic fatigue syndrome, and several autoimmune diseases. An important caveat: I only use the roots of Echinacea angustifolia and Echinacea purpurea (combined), quantified for good levels of alkylamides. Considerable evidence shows that the alkylamides are the most therapeutically relevant components of echinacea,6 but these are the compounds that are often not present in echinacea products due to (among other reasons) their instability during the manufacturing process. Echinacea is one of the most variable herbal products in the marketplace. It is clearly a case of buyer beware. To avoid disappointment with your clinical results seek out products that contain only the roots and are quantified for adequate alkylamide levels. Then recommend appropriate traditional doses. REFERENCES |
Kerry Bone, BSc (Hons), Dip Phyto, FNIMH, FNHAA, MCPP, is a practicing herbalist and head of research and development at MediHerb and principal of the Australian College of Phytotherapy. He can be contacted through Advertising | Classifieds | Cardpack | Datebook | Past Issues | Chiro History
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