Echinacea: a doubtful remedy

By SANDRA G. BOODMAN
WASHINGTON POST
Does it or doesn't it?
No one seems to know for sure, even the researchers who have studied whether the popular dietary supplement echinacea helps shorten the duration or intensity of that universal malady, the common cold.
A new federally funded study involving nearly 150 healthy undergraduates at the University of Wisconsin has found that the herb is no better than a placebo in treating a cold.
Researchers randomly assigned participants to take either echinacea or a placebo consisting of 333 milligrams of alfalfa, which resembles the whole herb. Those who took echinacea had colds that lasted an average of 6.27 days, while the placebo group's symptoms lasted an average of 5.75 days -- a difference of no statistical significance.
Not the final word
Yet even the study's lead author, Bruce P. Barrett, an assistant professor in the Department of Family Medicine at the University of Wisconsin, does not think his study should be the definitive judgment on the efficacy of echinacea, one of the three best-selling supplements in the United States. In 1999, annual sales of the product were estimated at $193 million.
"I don't think that this should be taken as the final word," Barrett said. "I think we're still in the position of not knowing the answer."
The chief reason for his caution, Barrett said, is the fact that his study contradicts a dozen other published reports concluding that echinacea does have some benefit in treating colds.
But these previous studies, Barrett said, have "significant limitations." Some were funded entirely by manufacturers, while others did not appear to be sufficiently "blinded." (Participants may have known whether they were taking echinacea or a placebo.) The Wisconsin study was funded by the Department of Health and Human Services, the National Institutes of Health and echinacea maker Shaklee Tecnica, which, the authors wrote, supplied the capsules but "had no role in the design, conduct or reporting of the data."
The study
Barrett noted that his team used pills containing the whole herb, not the liquid extract of echinacea, a form used in many previous studies. The pill form makes it more difficult to distinguish the placebo from echinacea but may have affected the results because some researchers believe that the extract is more potent and effective than the whole herb-form.
Because most studies have suggested that echinacea works better if taken soon after the appearance of cold symptoms, the participating students were instructed to call at the first sign of a cold.
Those who had symptoms for longer than 36 hours before they started treatment were eliminated from the study, as were students who were pregnant, had asthma or allergies, or were taking other medications, including antibiotics, antihistamines or decongestants.
Participants were required to take the pills containing either echinacea or a placebo for 10 days and to complete a questionnaire that detailed the duration and severity of symptoms, including dry cough, sore throat or congestion.
Barrett and his colleagues analyzed the results and failed to detect a meaningful difference between the two groups.
A cold problem
Though colds are a trivial, self-limiting medical problem for many people, they sometimes lead to more serious ilnesses, such as sinusitis or otitis media.
Studies have found that Americans get an average of two to six colds annually, which account for 45 million lost days of work and 22 million missed school days.
In a companion editorial, pediatrician Ronald B. Turner of the University of Virginia noted that given the lack of effective therapies for colds, "it is difficult to ignore the widespread use of echinacea and the persistence of anecdotal reports of benefit."
But so far, Turner concluded, "the scientific evidence of its efficacy is unconvincing."