Echinacea is widely regarded as an effective herbal remedy for the common cold. But research suggests that its effects may be all in the mind.
Investigators at the University of Virginia Medical School found that the herbal product did not have any "detectable effect" for treating the common cold.
"The results of this study demonstrate that extracts of (echinacea), 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," concludes the study, published in the New England Journal of Medicine.
Dr. Ronald Turner and colleagues studied 399 volunteer participants to analyze if any of three different types of echinacea helped treat or prevent rhinovirus type 39. This virus is associated with the common cold, and all volunteers were susceptible to it. The volunteers received either a placebo ("sugar pill") or echinacea three times a day. They were then inoculated with the cold virus and again received either echinacea or a placebo.
Results showed the echinacea preparations, endorsed by many groups - including the World Health Organization - as a viable cold treatment, weren't any more effective than the placebo.
"There were no statistically significant effects of the three echinacea extracts on rates of infection or severity of symptoms," states the study, which was funded by the National Center for Complementary and Alternative Medicine of the National Institute of Health, an American government agency.
In an editorial that accompanied the journal article, Dr. Wallace Sampson, editor of the Scientific Review of Alternative Medicine, noted the thoroughness of the study and concluded that "unless some obscure protocol violation occurred, the trial results are real." He also noted that previous studies on echinacea "were of small, inadequately controlled European studies sponsored by industry."
Though no benefits in terms of prevention or treatment were found, the study authors did not entirely write off echinacea. "Given the great variety of echinacea preparations, it will be difficult to provide conclusive evidence that echinacea has no role in the treatment of the common cold," the researchers state. "Our study, however, adds to the accumulating evidence that suggests that the burden of proof should lie with those who advocate this treatment."
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