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News :: Health |
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Study Says Popular Herb Has No Effect on Colds |
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by NYT via Joe Futrelle
Email: futrelle (nospam) shout.net (verified) |
28 Jul 2005
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By GINA KOLATA
Echinacea, the herbal supplement made from purple coneflower and used by millions of Americans to prevent or treat colds, neither prevented colds nor eased cold symptoms in a large and rigorous study. |
The study, being published today in The New England Journal of Medicine, involved 437 people who volunteered to have cold viruses dripped into their noses. Some swallowed echinacea for a week beforehand, others a placebo. Still others took echinacea or a placebo at the time they were infected.
Then the subjects were secluded in hotel rooms for five days while scientists examined them for symptoms and took nasal washings to look for the virus and for an immune system protein, interleukin-8. Some had hypothesized that interleukin-8 was stimulated by echinacea, enabling the herb to stop colds.
But the investigators found that those who took echinacea fared no differently from those who took a placebo: they were just as likely to catch a cold, their symptoms were just as severe, they had just as much virus in their nasal secretions, and they made no more interleukin-8.
Some researchers say still further investigation is needed, with stronger doses and with echinacea species and preparations different from those used in this study. But Dr. Stephen E. Straus, director of the National Center for Complementary and Alternative Medicine, the government agency that sponsored the new research, says he for one is satisfied that echinacea is not an effective cold remedy.
"This paper says it will not pre-empt a common cold, and it stands on top of prior studies saying it doesn't treat an established cold," he said, adding, "We've got to stop attributing any efficacy to echinacea."
While the herb is generally safe, he said, some people are allergic to it, and it can lower blood levels of theophylline, a drug used by people who have asthma, as well as levels of medications used to treat diabetes.
The study originated at the national center, where researchers were questioning what sort of supplements Americans were taking, and why. A national survey last year by the National Center for Health Statistics found that echinacea was the most popular natural product, used by some 14,665,000 people, or 40 percent of those who used natural products. The American Botanical Council, a nonprofit group that promotes the use of herbal supplements, says sales of echinacea products in 2004 were about $155 million.
"It's a product with remarkable traction," Dr. Straus said. "It has that traction because of the combination of folklore, myth and word of mouth which is much more than the science has borne out."
A few years ago, the National Center for Complementary and Alternative Medicine sponsored two other large studies of echinacea, one in children and the other in college students. In both studies, patients who already had a cold took the herb, which had no effect on their symptoms or the cold's duration when compared with a placebo.
Still, Dr. Straus said, he got complaints. "I had people call and say: 'You know, Steve, that's not the way I use echinacea. I don't wait until I have a cold. As soon as I feel a cold coming on, I take it and I nip it right in the bud.' "
And so, Dr. Straus said, the center leapt at the opportunity to study echinacea as a cold preventative with the most rigorous and sensitive test available. To begin with, he said, the 300-milligram dose was determined by a world-renowned expert, Dr. Rudolph Bauer, a professor of pharmaceutical biology at the Karl-Franzens University in Graz, Austria. That dose, Dr. Straus said, was one that had been employed in previous studies and the one that the World Health Organization had described as most often used by consumers.
"It was state-of-the-art methodology," he said. "We know exactly who gets rhinovirus dripped down their nostrils and when. We know whether they had echinacea beforehand or not."
And the investigators were looking at the relevant measures of infection and symptoms in their search for the virus and interleukin-8. In sum, Dr. Straus said, the researchers "got it right."
The study's findings were striking, said Dr. Ronald B. Turner of the University of Virginia, the leader of the research team.
"We were trying under the best possible conditions" to get echinacea to work, Dr. Turner said, explaining that the experimental design was so sensitive that it had found protective effects from other cold remedies that could not be duplicated in the real world.
But Dr. Bauer, one co-author, was among those saying the study should be repeated with other echinacea species, preparations and doses.
"I am always in favor of further studies," Dr. Bauer said. He himself takes echinacea, he said, and will continue to do so.
The American Botanical Council also called for more research. Mark Blumenthal, the group's founder and executive director, said in a press release that among other things, the herb should be tested at a higher dose.
But in an editorial accompanying Dr. Turner's paper, Dr. Wallace Sampson, editor of The Scientific Review of Alternative Medicine, which analyzes alternative-medicine claims, said there was no reason to have believed that echinacea was effective against colds in the first place. In the early 20th century, echinacea "somehow became popular for the treatment of respiratory illness in Germany," Dr. Sampson wrote, while in the United States it was used for wound healing and other purposes for which today people would take an antibiotic. Its use faded away when real antibiotics were discovered, but it re-emerged in the 1960's as a cold remedy, with no particular reason to think it would work.
Now, with increasing evidence that echinacea does not work for colds, scientists are confronting a problem, Dr. Sampson said, in that "there is no 'demarcation of the absurd,' a point at which it is unwise to pursue an investigation further."
For Dr. Turner, that point is here.
"We should assume that echinacea does not work until somebody proves it does," he said. That, he added, "is the flip side of where we've been." |
See also:
http://www.nytimes.com/2005/07/28/health/28cold.html?pagewanted=print
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