By Evans, Jeff
Clinical Psychiatry News , Vol. 35, No. 9
Users of echinacea supplements in clinical trials reduced their odds of developing the common cold by more than half, according to findings from a meta-analysis of 14 published, randomized, placebo-controlled trials.
When patients in the trials caught a cold, those who used echinacea supplements also cut a mean of 1.4 days from the duration of their illness, compared with patients who received a placebo. The trials involved preparations of the three most common Echinacea species (E. purpurea, E. augustifolia, and E. pallida) either alone or in combination with other supplements.
Although agencies such as the World Health Organization, the Canadian Natural Health Products Directorate, and the German Federal Institute for Drugs and Medical Devices Commission E have supported the use of echinacea for the common cold, "there is controversy about the efficacy of echinacea for the prevention or treatment of the common cold with some studies showing benefit and others showing a null effect," wrote lead investigator Sachin A. Shah, Pharm.D., of the University of Connecticut School of Pharmacy, Storrs, and associates (Lancet Infect. Dis. 2007;7:473-80).
The meta-analysis, which encompassed 1,356 patients in tests of echinacea's effect on the incidence of the common cold and 1,630 patients in determining its effect on the duration of colds, showed that echinacea users had a significantly lower odds of contracting a cold (58% lower) than did placebo patients.
Nine trials evaluated the effect of echinacea on the incidence of colds, while seven tested its effect on reducing the duration of colds (two trials examined both end points).
Prophylactic use of echinacea reduced the incidence of naturally occurring colds by 65%, compared with placebo. Echinacea dropped the incidence of colds by only 35% when investigators directly inoculated participants with rhinovirus, which suggests that echinacea has a modest effect on rhinovirus but marked effects against some of the 200 other viruses that are capable of causing the common cold, the researchers wrote. …