More doubts about echinacea for preventing colds

By Amy Norton

NEW YORK (Reuters Health) - The popular herbal cold-fighter echinacea may not work as advertised, a new clinical trial shows.

Echinacea, which is derived from the coneflower, has long been touted as a way to bolster immunity and prevent or ease the common cold. But studies have come to conflicting conclusions as to whether the herb is truly effective.

This latest study, published in the Annals of Allergy, Asthma and Immunology, adds to doubts about echinacea's ability to prevent colds.

Researchers at the University of California San Francisco found no clear evidence that echinacea prevented nasal congestion, sore throats or other cold-season woes among 58 volunteers they followed for eight weeks.

Study participants were randomly assigned to take either three echinacea capsules or three parsley-containing placebo capsules twice a day for the entire study period. Once a week, the researchers asked the volunteers whether they had suffered a sore throat, runny nose, headache or other cold symptoms over the previous week.

Overall, the echinacea group reported nine "sick days" per person, while the placebo group reported 14. The difference, however, did not hold up when the researchers performed a statistical analysis of the data -- meaning the difference in sick days could have been due to chance.

"Although echinacea is touted as an immune stimulant and sold in almost all health food stores, this study is one of many with equivocal findings that really do not support the use of echinacea to prevent the common cold," lead researcher Dr. Joelle O'Neil told Reuters Health.

This study and others suggest that there is no harm to taking standard, commercially available echinacea products, noted O'Neil, who is now a family practice physician with Kaiser Permanente in Fresno.

But neither is there reason to recommend the herb for preventing colds, she added.

The study did not address whether echinacea is useful for lessening the severity of cold symptoms, or speeding people's recovery, O'Neil noted.

SOURCE: Annals of Allergy, Asthma and Immunology, April 2008.