Echinacea Disappoints: There's Still No Cure for the Common Cold

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Echinacea Disappoints: There's Still No Cure for the Common Cold

Herbal Medicine

Journal article

By: Nathan Seppa

Date: July 30, 2005

Source: Seppa, Nathan. "Echinacea Disappoints: There's Still No Cure for the Common Cold." Science Service 70, no. 1 (July 30, 2005).

About the Author: Nathan Seppa is a writer and magazine journalist specializing in the areas of biomedicine, science, and the social and behavioral sciences. He has been a staff writer for biomedical Science News Online, Science, and the APA Monitor.


Herbal products and supplements are rarely well understood by the American public. There is an interesting dichotomy in that few people would take any form of prescription medication before being educated by their local pharmacist about its mechanisms of action and potential side effects, as well as its possible interactions with other medications currently being taken. However, many readily purchase and ingest herbal supplements based on media advertisements, suggestions of friends or colleagues, or the advice of a health or natural food store employee, without first researching the possible side effects and interactions of supplements. There is often a tacit assumption among the herbal and botanical supplement using public that natural substances are likely to be beneficial, and they cannot cause harm.

The Dietary Supplement Health and Education Act of 1994 defines any form of dietary supplement, whether herbal, botanical, enzyme, amino acid, vitamin or mineral, as a food substance, taken by mouth and intended to supplement the diet. Supplements are not considered medicinals, and are therefore not currently regulated by the Food and Drug Administration (FDA) with the same rigorous standards as are pharmaceuticals. The FDA only regulates supplements if complaints are made against particular manufacturers, or the specific substances that are created and marketed by them. The Federal Trade Commission (FTC) is the body that has oversight concerning whether the producers of supplements are advertising truthfully. However, the National Center for Complementary and Alternative Medicine (NCCAM) has significant jurisdiction over the production, product claims, safety and efficacy, and marketing statements made by the purveyors of dietary supplements, and they oversee extensive research in that area. These products fall under the general category of biologically based therapies.


Echinacea disappoints: there's still no cure for the common cold. A folk remedy touted as a cold treatment has failed its most recent—and possibly most exacting—test. Volunteers exposed to a cold virus and given the herbal supplement echinacea fared no better than did virus-exposed participants who received an inert substance, researchers report in the July 28 New England Journal of Medicine.

The U.S. study is the third in 3 years in which echinacea failed to alleviate colds in children or, as in this case, young adults. These findings run counter to earlier reports, most out of Europe, that echinacea revs up an immune response against cold viruses (SN: 3/27/99, p. 207).

For the new study, researchers recruited 399 young adults. Some received drops of Echinacea angustifolia extract and others got placebos. After a week, all volunteers received nasal sprays containing rhinovirus type 39, a common cold virus, and were sequestered in a hotel room for 5 days.

After exposure, volunteers getting echinacea continued to take it. Some participants getting the placebos were switched to echinacea, while others continued with the placebos.

None of it mattered, says study coauthor Ronald B. Turner of the University of Virginia in Charlottesville. More than 80 percent of the people in each group became infected with the virus, and roughly three-fifths of each group showed cold symptoms within a week. The severity of the symptoms also was the same across the groups.

Furthermore, blood tests showed no significant immune boost from echinacea.

"While this study tested only E. angustifolia, there is considerable overlap in the chemical constituents of the three purple cone-flower species from which echinacea is derived," says Benjamin Kligler of the Albert Einstein College of Medicine in New York.

Therefore, the new study's findings "might apply to the other Echinacea species as well," says herbal medicine specialist Wallace Sampson of Stanford University.

Echinacea formulations often contain more than one species of the plant (SN: 6/7/03, p. 359). Since the preparations are sold as dietary supplements and not drugs, the Food and Drug Administration doesn't regulate their effectiveness or content.

"Three big negative trials have now come out," says Bruce P. Barrett of the University of Wisconsin-Madison. In the study that he led, reported in 2002, college students with colds fared the same whether they got placebos or a mix of the Echinacea species. In a 2003 report, researchers at the University of Washington in Seattle found that Echinacea purpurea, a common ingredient in formulations, was no weapon against colds in children.

Barrett and Kligler, both physicians, say that they wouldn't discourage people currently using echinacea from continuing to do so, because the supplement is generally safe and may have a significant placebo effect. "But I sure wouldn't go out and tell people who don't believe in it to start taking it," Barrett says.


The purchase and use of dietary supplements of all kinds has increased enormously in the United States since the 1970s. In keeping with the growing interest in promoting health, supplements are claimed to stave off the effects of aging (particularly among the "baby boom" generation) and naturally enhance physical abilities, such as energy, strength, and endurance (without the use of steroids). Among the largest consumers of supplements are people with chronic or life-threatening illness, athletes seeking to improve capacity or performance, and people who are trying to lose weight. Many also use vitamins, herbal preparations, or botanical supplements in an effort to treat common illnesses, such as the flu, other viral infections, or colds.

Although there have been many research studies concerning the safety and efficacy of various dietary supplements, much of it has lacked the precision and scientific rigor of the clinical trials undergone by the manufacturers of pharmaceuticals in the United States, so it has been challenging to accurately assess the claims made by manufacturers. Another significant issue is the lack of standardization in the manufacture and production of supplements: pharmaceuticals are produced according to specific formulations, and at standard (universal) dosages based on safety and efficacy studies. This is not the case for non-pharmaceutical biological preparations. Many herbal and botanical supplements are made of complex mixtures, comprised of several, or a great many, ingredients. It is very difficult to evaluate purity, quality, and consistency of formulation under those circumstances. When NCCAM and others have completed analyses of many multi-ingredient preparations, they have sometimes found significant differences between the amounts of each substance labeled and what was determined by chemical analysis. Dietary (used interchangeably with nutritional throughout) supplements are not subject to the standards set for medicinals by the FDA, referred to as good manufacturing practices, or GMPs.

Some of the nutritional supplements whose limited study has shown sufficient promise to warrant larger scale research, are: glucosamine hydrochloride and chondroiten sulfate for use with osteoarthritis, shark cartilage for use with lung cancer, Saint John's wort for mood disorder (although the current results regarding its use in treating depression are equivocal at best), black cohosh for treating symptoms associated with menopause, ginkgo biloba for use as a protection against the development of dementia, saw palmetto and vitamin E for use in disorders of the prostate, and melatonin or valerian root for use with sleep onset disorders. That these substances are being studied more closely does not imply that they will be proven efficacious. Several supplements have been shown to block or interfere with the mechanisms of action of prescription pharmaceuticals, such as Saint John's wort's capacity for neutralizing the effects of many prescription medications, and ginkgo biloba's capacity for potentiating the effects of anticoagulants, thereby increasing potential bleeding problems in some people who take them together. A potentially significant association was demonstrated between both kava extract and comfrey root and liver failure, so both are now sold with that warning on the label. Ephedra was discovered to cause potentially lethal side effects in some people and has been banned by the FDA. Many vitamins, herbal preparations, and botanical supplements interfere with the mechanisms of action of different chemotherapy drugs.

Both the National Center for Alternative and Complementary Medicine and the Federal Food and Drug Administration continue to explore herbal compounds for use in the treatment of disease and its symptoms through research and clinical trials.



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