WEDNESDAY, July 27, 2005 (HealthDay News) -- While the herbal remedy echinacea purportedly helps reduce the incidence and severity of the common cold, a new study says that's just not so.
In a study that included about 400 healthy volunteers, researchers found that echinacea neither prevented colds nor eased the symptoms for people already infected with a cold.
"We found no effect of echinacea used for prophylaxis or for treatment on either infection rates or symptoms," said Dr. Ronald Turner, lead author of the study and a professor of pediatrics at the University of Virginia.
"At this point, any claims of benefit for echinacea should be viewed with skepticism, and the burden of proof should now be on the folks that think it works," he added.
Results of the study appear in the July 28 issue of the New England Journal of Medicine.
Echinacea is an herbal remedy made from the roots of the Echinacea angustifolia plant. It was used by Native Americans to treat infections and wounds, according to background information in the article. And it was in the 1800s that echinacea first became popular as a cold remedy.
While early studies on echinacea's benefits were small and inconclusive, more recent research has clearly shown that the herb isn't effective against the common cold, according to Dr. Wallace Sampson, an emeritus clinical professor of medicine at the Stanford University School of Medicine, who wrote a perspective piece accompanying the study in the same issue of the journal.
This study, said Turner, should put the echinacea debate to rest. "It puts it to rest in my mind," he said. However, he also said there will likely still be people who continue to believe that echinacea works against the common cold.
For the double-blind, placebo-controlled study, the researchers made three different echinacea preparations from a single lot of echinacea root.
A group of 399 volunteers were then divided into seven groups to assess each preparation and compare it to a placebo for both the prevention and treatment of colds. Three groups were given one of three echinacea preparations three times daily for seven days prior to being exposed to the virus -- rhinovirus -- that causes the common cold, and then for five days after exposure. Three groups weren't given the echinacea preparation prior to being exposed, but were given the herbal remedy for five days after rhinovirus exposure. The final group received a placebo both before and after rhinovirus exposure.
The dosage of echinacea contained the equivalent of about 300 milligrams of echinacea root, according to the study.
The researchers then monitored nasal secretions for signs of infection and inflammation. They found no significant differences between the groups for infection rates or illness severity.
"This study adds to the bulk of literature that shows that echinacea doesn't work," said Sampson.
While Sampson said he felt this was a well-done study, he added that the larger question is why the scientific community continues to conduct large-scale clinical trials on remedies that are largely unproven.
"It puts the cart ahead of the horse to do large clinical trials to disprove efficacy," he said. "What's happened in the past 30 years is that advocates of alternative medicine successfully turned things around to put the burden of proof on the scientific community and the taxpayers."
Normally, before large clinical trials are done, a medication has to be proven safe and effective in smaller studies first. Sampson said some people argue that researchers have to test these products because so many people are using them. But, he said, even when products are discredited, people continue to use them. He said that research, and limited public funding, should focus on products that have a "reasonable chance of efficacy."
When it comes to herbal remedies, the bottom line is "that they are drugs and toxins and most plant species out there have a more likely chance of harming one than helping one," said Sampson.
More information
To learn more about the common cold and ways to treat or prevent it, visit the National Institute of Allergy and Infectious Diseases.
