Low-Dose Echinacea Ineffective in Cold Prevention

Low-Dose Echinacea Ineffective in Cold Prevention

CHARLOTTESVILLE, Va.Differentpreparations of echinacea were not effective at preventing or treating thecommon cold in a study of almost 400 volunteers, according to a study publishedin the July 28 issue of the New England Journal ofMedicine (353, 4:341-48, 2005). In the study, fundedby a grant from the National Center for Complementary and Alternative Medicine(NCCAM), researchers from U.S. and Austrian universities administered one ofthree different preparations of Echinacea angustifolia,made using supercritical extraction, to student volunteers either seven daysbefore or immediately after a viral challenge with rhinovirus. Dosage was 900mg/d of E. angustifolia root,administered in three equal doses. At the end of the study, there were nostatistically significant effects of echinacea on the rate of infection orsymptom severity.

Mainstream media outlets from Reuters to CNN and the LosAngeles Times picked up on the story, with most presscoverage noting the study appeared to only confirm the fact that echinacea isineffective for its touted purpose.

Within the herbal arena, industry members were questioning thefindings of the study, drawing attention to questions on dosage as well as thesingle herb varietal used in the study.The American Botanical Council (ABC)noted the echinacea extracts were made in a university lab and may not correlatewith commerciallyavailable products. It would have been optimal if this trialhad tested the echinacea preparations at more frequent and/or higher doses, said Mark Blumenthal, founderand executive director of ABC. The best that can be said is that thesespecific laboratory-produced extracts, at the dose given in the trial, under thespecific design of this trial, did not produce any measurable effect. However, this is not a definitive trial on the efficacy ofechinacea, nor should the results be generalized to echinacea preparationswidely available. ABC has posted the complete chapter on echinacea from its ABCClinical Guide to Herbs on its Web site (www.herbalgram.org) for public education.

Representatives from the American Herbal Products Association(AHPA) also questioned the dosage used in the study and NCCAMs initialevaluation on the study protocol. Just this month, NCCAM announced a greateremphasis on the need for preclinical research in the areas of complementary andalternative medicine, where NCCAM provides funding, said Steven Dentali,Ph.D., vice president for scientific and technical affairs at AHPA (www.ahpa.org). Had this policy been in place when this study was funded in2002, it is doubtful that this clinical research would have been supported inadvance of a thorough understanding of the dose that is known to produce apharmacological effect.