Latest Echinacea trial not so clear cut, herbal experts say

Latest Echinacea trial not so clear cut, herbal experts say

A recently published clinical trial on Echinacea failed to show a statistically significant benefit for cold symptoms.

The Grinch brought more bad news for the Echinacea industry in late December, with the publication of another clinical trial on the embattled herb that failed to show a statistically significant benefit for cold symptoms.

Headlines in the mainstream media didn't mince any words.

"Echinacea ineffective against colds" - The Boston Globe

"Got a cold? Study says Echinacea won't help much." - USA Today

"Echinacea does not cure colds" - U.S. News and World Report

The problem, says Mark Blumenthal, founder and executive director of the American Botanical Council, is that the study results were not quite so clear cut.

The trial, published in the Annals of Internal Medicine, was possibly the largest randomized, controlled trial to date, with 719 subjects taken from the general population in Wisconsin. Unlike other trials in which a rhinovirus was inhaled in a controlled situation, this trial tested short-term use of Echinacea preparation within 24 hours of the appearance of naturally acquired cold symptoms.

The trial measured cold symptom severity and the duration of the symptoms, with secondary endpoints measuring levels of interleukin-8 and neutrophil, which are markers for immune response.

As Blumenthal, who was widely interviewed by the media, explained, the trial used a "good-quality Echinacea preparation" made by MediHerb of Australia and distributed by Standard Process of Wisconsin.

"This trial was also designed and conducted by people who are experts in Echinacea research and have published extensively on Echinacea clinical trials," he said. This includes lead researcher Bruce Barrett, MD, PhD, a professor of family medicine at the University of Wisconsin in Madison; and Kerry Bone, founder of MediHerb and an internationally respected author of herbal books for health professionals.

So what, exactly, did this trial find?

"There was a slight trend toward benefit in symptom reduction in both Echinacea groups, with a reduction in duration by about 12 hours, which, although not statistically significant, the authors note may be considered clinically significant by some patients," Blumenthal said.

The authors provided a cautiously worded and reasonable conclusion, he said.

"This dose regimen of the Echinacea formulation did not have a large effect on the course of the common cold, compared with either blinded placebo or no pills," the study authors stated. "However, the trends were in the direction of benefit, amounting to an average half-day reduction in the duration of a weeklong cold, or an approximate 10 percent reduction in overall severity."

However, at the same time, "Illness duration and severity were not statistically significant with Echinacea compared with placebo. These results do not support the ability of this dose of the Echinacea formulation to substantively change the course of the common cold," the authors wrote.

The MediHerb preparation used in the study was a tablet form that contained dried, concentrated extracts of two types of Echinacea, the equivalent of 675mg of E. purpurea root and 600mg of E. angustifolia root, each standardized to 2.1mg of alkamides, one of the key biologically active chemical compounds found in Echinacea roots.

The tablet contained a daily dose equivalent of 10.2g of (both types) dried Echinacea root during the first 24 hours after the subject noticed the first symptoms of cold, and 5.1g per day of dried Echinacea root consumed during the next four days.

The study was funded by the National Center for Complementary and Alternative Medicine.

Other research

There are three species of Echinacea found in herbal preparations: Echinacea angustifolia, E. pallida and E. purpurea, with the latter being the most popular.

One of the challenges of conducting and comparing research on the herb's efficacy are the many different types of preparations on the markets, both in species but also in how they are used: dried herb; alcohol extracts from the root or above-group part of the plant; or even fresh-pressed juice from the fresh aerial parts.

"To further complicate matters for researchers who are attempting systematic review or meta-analysis of clinical trials on these preparations, there are mixtures of these Echinacea materials from two or three species," Blumenthal said. "Since Echinacea species and their plant parts contain different chemical profiles, these various products can have different activities and benefits — as reflected in some of the clinical trials."

According to Blumenthal, the most compelling clinical literature to date supports the clinical efficacy of two different brands of extracts of E. purpurea root. For the first, there have been three clinical trials on the Echinaforce extract produced by A. Vogel in Switzerland, imported to the U.S. and distributed in health food stores by Bioforce USA. The second brand, called Echinamide, on which two published clinical trials have shown some benefit for cold symptoms, is produced in Canada by Natural Factors and sold in the U.S. in health food stores.

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