Dosage Too Low in New Echinacea Trial, Says Herbal Science Group

Main Category: Complementary Medicine / Alternative Medicine
Article Date: 02 Aug 2005 - 3:00 PDT

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The nonprofit American Botanical Council (ABC), an Austin, Texas-based research and education organization, has reviewed a new clinical trial on the popular herb echinacea for use in a specific kind of induced virus, published Thursday in the New England Journal of Medicine.1 The study concluded that the echinacea preparations did not prevent or help treat symptoms of a specific virus applied to the test subjects. ABC has found several aspects of the design of the study worthy of clarification, and comments on the potential misinterpretations of the significance of this study.

First, the extracts used were made in a university laboratory and do not correlate with commercial echinacea products currently available to consumers. Second, the dosages used in this trial were probably too low. The echinacea preparations used in the study might have shown activity at more frequent dosing intervals and/or higher dosage levels - as is often the case with contemporary echinacea use.

The new trial utilized extracts made from the roots of a species of echinacea called Echinacea angustifolia. The randomized, double-blind, placebo-controlled, seven-arm trial was conducted on 437 college students who had a particular type of rhinovirus inserted into their nostrils (the results were calculated on 399 subjects). In the trial, the echinacea preparations were tested to see if they had a preventive effect or if they could help treat the symptoms caused by the rhinovirus. The students who received the three different echinacea preparations and were sequestered in a hotel room did not experience fewer infections, fewer symptoms, or a reduction in the duration of symptoms, compared with those who received the placebo.

The trial utilized three doses of 1.5 milliliters each of the three laboratory-produced echinacea extracts, presumably equivalent to about 300 milligrams of the dried powdered root in each dose (equivalent to 900 mg per day of the dried root). This level was chosen for the trial because it is the dose recommended by the German government's expert herb panel called the Commission E, which had conducted reviews of the research published on various types of echinacea in the scientific and medical literature in the early 1990s.2

According to ABC various international monographs have acknowledged the generally higher dose used for echinacea root products. The World Health Organization (WHO) monograph for Echinacea root ("Radix Echniaceae") has a dosage for Echinacea angustifolia root at the equivalence of 3 gm per day of the dried root.3 This same dosage is also acknowledged in the more recently developed draft monographs on Echinacea from the Canadian Natural Health Products Directorate.4

This dosage level is about 330% higher than the dosage of the echinacea preparations given in the NEJM trial. This supports ABC's contention that the preparations may have been under-dosed and that the trial might have shown a potentially positive trend if a higher dosage and/or increased frequency of administration had been followed.

"It would have been optimal if this trial had tested the echinacea preparations at more frequent and/or higher doses," said Mark Blumenthal, Founder and Executive Director of ABC. "Dosage is one of the most important aspects in assessing any therapeutic agent. Many clinicians who recommend echinacea for treatment of upper respiratory tract infections related to colds and flu normally utilize a frequency of use and/or a total daily dose that is higher than the one used in this trial. This is also true for consumer self-medication with many commercial echinacea preparations according to some label dosage suggestions."…. CONTINUES …. American Botanical Council

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Article adapted by Medical News Today from original press release.
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Anita Gonzales. "Dosage Too Low in New Echinacea Trial, Says Herbal Science Group." Medical News Today. MediLexicon, Intl., 2 Aug. 2005. Web.
15 Feb. 2012. <http://www.medicalnewstoday.com/releases/28478.php>

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APA

Anita Gonzales. (2005, August 2). "Dosage Too Low in New Echinacea Trial, Says Herbal Science Group." Medical News Today. Retrieved from
http://www.medicalnewstoday.com/releases/28478.php.

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