Herbal Science Group Says Dosage Too Low in New Echinacea Trial
Herbal Science Group Says Dosage Too Low in New Echinacea Trial
(Austin,
TX, July 27, 2005). 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,
being 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.”
Blumenthal
added. “The researchers have previous experience in researching
echinacea and have done an admirable job in testing a species of echinacea (i.e., E.
angustifolia) that has not been adequately researched.” But he hastened
to add, “The most accurate statement that can be said about this trial
is this: These specific laboratory-produced echinacea extracts, at the dose given
in the trial, under the specific design of this trial, did not produce any measurable
effect.”
He emphasized, “This is not a definitive trial on the efficacy of echinacea,
nor should the results be generalized to echinacea preparations widely available.
Unfortunately, the conclusion that may be drawn by some media who report this
study may state that ‘echinacea is ineffective,’ but this would be
an incorrect conclusion based on the design of this study and the evidence in
the existing literature.”
“Dosing people for rhinovirus in a hotel
does not necessarily mimic real life,” said Bruce Barrett, MD, PhD, an
Assistant Professor of Family Medicine University of Wisconsin School of Medicine
and an author of several previous critical reviews on echinacea clinical trials.
He noted that the patients were possibly relatively resistant to the echinacea
treatment. “College
kids are immunocompetent,” he stated, referring to the relative health
of the test subjects in the trial. “It may have been better to test older
people to see how they might have faired.”
However, Dr. Barrett was generally complimentary about the trial in general. “This
is a very valuable study and quite helpful, although it has some significant
limitations, including product, sample, and population,” he stated. “In
general, you may want to have about 100 people per treatment group for more statistical
significance rather than only about 50 per group used in this trial.”
In
general, products marketed as “Echinacea” are extremely
popular in the United States. Echinacea ranked second in sales in mainstream
market retail stores in 2004, according to an article in ABC’s journal HerbalGram.5
Total sales of echinacea products in all channels of trade in the United States
in 2004 was estimated at about $155 million, according to data compiled by Nutrition
Business Journal.
Blumenthal also added that although it was formerly quite popular, there
has been a trend away from using Echinacea angustifolia root in commercial
herbal products based on increased concerns by many responsible members of the
herb community regarding conservation and sustainability of wild medicinal plants. Echinacea
angustifolia is generally more difficult to cultivate commercially than the
other two more popular species of echinacea (E. pallida and E. purpurea),
and so more material from these species are found in products on the North American
market.
Blumenthal points to a body of clinical evidence that supports the use
of various echinacea preparations for treating symptoms associated with colds
and flus. A therapeutic
monograph on Echinacea is
available in The ABC
Clinical Guide to Herbs, ABC’s
reference book and continuing medical education module.6 The monograph summarizes
21 clinical trials on various echinacea preparations for colds, flus, upper respiratory
tract infections, and other uses. ABC has posted the complete echinacea chapter
including this monograph on its website as
an educational service to the public.
The
study has generated significant media attention. ABC and Blumenthal have been
contacted by a variety of news sources, including: the Associated Press, Bloomberg
Business News, CNN, the Los Angeles Times, NBC Nightly News with Brian
Williams, the New York Times and USA Today.
About the American Botanical Council
The American Botanical Council is the nation's leading nonprofit
organization addressing research and educational issues regarding herbs and medicinal
plants. The 17-year-old organization occupies a 2.5 acre site in Austin, Texas,
where it publishes HerbalGram ,
a peer-reviewed journal. ABC is also the publisher of The
ABC Clinical Guide to Herbs,
a continuing education and reference book, which contains extensive monographs
on the safety and efficacy of 29 popular herbs, including echinacea.6 More information
on echinacea is available on ABC’s extensive website, http://www.herbalgram.org/.
References
1. Turner RB, Bauer R, Woelkart
K, Hulsey TC, Gangemi DJ. An evaluation of Echinacea angustifolia preparations
in experimental rhinovirus infections. N Engl J Med 2005;353:341-348.
2.
Blumenthal M, Busse WR, Goldberg A, Hall T, Riggins CW, Rister RS, eds. Klein
S, Rister RS, trans. The Complete German Commission E Monographs - Therapeutic
Guide to Herbal Medicines. Boston: Integrative Medicine Communications; Austin,
TX: American Botanical Council, 1998.
3. Echinacea Radix. In: WHO monographs
on selected medicinal plants. Geneva:
World Health Organization, 1999.
4. Ehinacea. Natural Health Products Directorate.
Health Canada. Draft Jan 2004. Available at: http://www.hc-sc.gc.ca/hpfb-dgpsa/nhpd-dpsn/mono_echinacea_e.pdf Accessed,
Jul 27, 2005.
5.
Blumenthal M. Herb sales down 7.4 percent in mainstream market. HerbalGram 2005;66:63.
6.
Echinacea. In: Blumenthal M, Hall T, Goldberg A, Kunz T, Dinda K, Brinckmann
J, et al, eds. The ABC Clinical
Guide to Herbs. Austin, TX: American Botanical Council, 2003.