Echinacea, the most popular herbal supplement in the United States, cuts the chances of catching the common cold by 58 percent and reduces the duration of the common cold by 1.4 days, according to a University of Connecticut study.
Conducted by researchers in UConn's School of Pharmacy, the study, known as a meta-analysis, combined the results of 14 previous clinical trials involving more than 1,300 patients followed for Echinacea's effect on preventing the common cold and more than 1,600 patients followed for Echinacea's effect on limiting the duration of the common cold.
The new UConn findings stand in contrast to a study published recently in the New England Journal of Medicine, which discounted Echinacea's cold-fighting effects, the researchers report.
Instead, the UConn research bolsters a previous study that found Echinacea to be an effective treatment for the common cold and also provides new evidence of Echinacea's added cold prevention benefits.
Because of the size and scope of the UConn meta-analysis, which included only randomized, placebo-controlled, peer-reviewed studies, the researchers were able to observe effects the smaller, individual studies, including the New England Journal of Medicine study which was included in the UConn review, were not able to determine alone. The UConn researchers also were able to examine Echinacea's effects with and without the presence of additional supplements and whether exposure to viruses occurred naturally or study subjects were inoculated with a cold virus.
- Echinacea reduced the incidence of contracting the common cold whether it was taken alone or in combination with other herbal supplements.
- Echinacea reduced the chance of catching the common cold whether study subjects were exposed to viruses naturally or inoculated with a particular virus as part of the study.
"The take home message from our study is that Echinacea does indeed have powerful cold prevention and cold treatment benefits," said Assistant Professor of Pharmacy Practice Craig Coleman, the lead author of the study. "The significance of that finding becomes clear when you consider Americans suffer from one billion colds annually and spend about $1.5 billion annually for doctor's visits and another $2 billion annually on non-prescription cough and cold treatments."
In addition to being smaller in size than the UConn meta-analysis, the New England Journal of Medicine study used the least common of the three species of Echinacea and administered it at a dose more than three times lower than recommended, Coleman explained. The study also inoculated subjects with rhinovirus, which is one of the most common cold-inducing viruses, but there are more than 200 viruses capable of causing the common cold, Coleman added.
Coleman and his fellow researchers, however, stop short of endorsing Echinacea as the standard practice for preventing and treating colds based on existing research.
More than 800 products containing Echinacea are currently available in different forms, containing different species of the plant, different parts of the plant and different doses and it has yet to be determined whether it is one, a few or the combined effects of multiple Echinacea constituents that enhance the immune system, the researchers wrote.
Coleman said future studies are needed to control for variables such as Echinacea species and product preparation as well as to determine the proper dose before Echinacea can become the first line prevention and treatment for the common cold.
UConn Associate Professor of Pharmacy Practice C. Michael White and School of Pharmacy research fellows Sachin A. Shah and Mike Rinaldi and former research fellow Stephen Sanders also collaborated on this research.
Materials provided by University of Connecticut.