Echinacea, derived from the purple coneflower, is an herb sold over the
counter as an immune-system strengthener and cold remedy.
Despite a few studies that found the herb made a difference for cold
sufferers, "there is no clear consensus about whether echinacea can benefit
human health," lead author Dr. Bruce P. Barrett and colleagues write in the
December 17th issue of the Annals of Internal Medicine.
To investigate, Barrett and a team of researchers at the University of
Wisconsin in Madison compared the effects of echinacea in capsule form with a
placebo pill in college students who believed they were coming down with a cold.
To participate in the study, the students had to report at least 2 of 15
listed cold symptoms. Participants were excluded if they reported having any of
the symptoms for more than 36 hours or if they were taking antibiotics,
antihistamines or decongestants.
The investigators did not detect a difference in cold duration between the
echinacea and placebo groups, nor did they find any difference between the two
groups in symptom severity, according to the report.
Colds lasted an average of 6 days for people in both groups, the report
indicates.
Nonetheless, the authors note that echinacea is sold in a variety of forms
and that just because the form of echinacea they tested had no health benefit
doesn't necessarily mean that other forms will not help cold sufferers.
"Because (plant) chemical constituents vary among botanical species, growing
conditions, plant part and extraction method, it is possible that one
preparation would provide benefit while another would not," Barrett and
colleagues write.
Barrett's team is calling for more research on echinacea's cold-fighting
potential.
The echinacea capsules used in the current study contained a combination of
whole unrefined plant material, including roots from Echinacea angustifolia and
herb and root from Echinacea purpurea.
The students took four tablets six times for the first day and four tablets
three times a day until cold symptoms resolved or for 10 days.
