Does Echinacea Fight Colds?
By Megan Phelps
Echinacea is one of the most popular, most studied and most controversial herbal remedies in the world. Some scientists say there's no evidence it fights colds. Herbal practitioners say the science is incomplete.
In 2004, a US government survey found that echinacea was the nation's most popular herbal medicine, used by 40 percent of those who bought herbal products. But echinacea's effectiveness was called into question last July, when the New England Journal of Medicine published the results of a large clinical trial that found the herb did not help treat or prevent colds.
The study, funded by the National Center for Complementary and Alternative Medicine (NCCAM), made headlines across the country, most of them declaring the end of echinacea as a cold remedy.
Does that mean you should throw away the echinacea in your medicine cabinet? Not so fast, says Mark Blumenthal, executive director of the American Botanical Council (ABC), a nonprofit organization that promotes research and education on medicinal plants.
"The study was well conducted; it was very well controlled, but this is not the definitive study," Blumenthal says. "It needs to be seen in the context of the many other trials of echinacea." The ABC, which publishes in-depth reference information on medicinal herbs, has posted research on echinacea at www.herbalgram.org. Among the 21 studies listed, 18 found positive results, with three finding no significant effects.
As the researchers themselves noted in the NCCAM study, it's difficult to prove or disprove that echinacea fights colds because so many forms of the herb are used. Commonly called purple coneflower, echinacea is a genus with three different species that are used medicinally: Echinacea purpurea, E. pallida and E. angustifolia. Medicinal preparations may contain either the root or the aboveground portion of the plant from any of these species, and they may be prepared as dried herbs available in capsules, liquid extract sold as a tincture or even dried extracts. Even the geographic location of the plant and the time of year it was harvested can affect its chemical composition, according to the researchers who conducted the NCCAM study.
For that trial, the researchers used a tincture of E. angustifolia root three times a day in dosages that were equivalent to 300 milligrams. The trial was conducted on 437 college students who were given cold viruses and then sequestered in hotel rooms. Those given extracts of E. angustifolia did not display any fewer infections or shorter duration of the cold symptoms than those who did not receive the herb; the extracts were not any more effective when given before exposure to the virus than they were in reducing its effects.
One of the study's co-authors, Dr. Rudolf Bauer, told The New York Times that different dosages, species and preparations of echinacea should be tested, and that he personally will continue to take echinacea.
Blumenthal says that while this study provides useful information about this preparation of E. angustifolia at that particular dosage, he thinks the dosage tested should have been higher. The 900 milligrams-per-day level was determined according to the echinacea guidelines published for a different species (E. pallida) by Commission E—a German government committee that compiled a widely used reference. But more recent standards, including those set by the World Health Organization and the Canadian National Health Products Directorate, recommend a dosage level of 3,000 milligrams a day.
"The whole thing is about dosage," Blumenthal says. "It's like taking one-third of an aspirin and wondering why you still have a headache."
Blumenthal's advice is to take echinacea the same way he does. As soon as he notices cold symptoms, Blumenthal takes a tincture of immune-boosting herbs including echinacea, astragalus, andrographis and elderberry syrup, about two droppersful every two to four hours for two days. "I take big doses right away, and usually within 24 to 36 hours, I have it knocked out.