Echinacea - cold cure or hot air?

Related tags Echinacea Common cold Colds

Echinacea's reputation for chasing off the common cold has made it
one of the most widely used herbal products on the market, but a
study published today casts doubt on its efficacy. Jess
Halliday discusses the merits and shortfalls of the study, and
what it may mean for the industry.

The joint US-Austrian study, funded by the National Center for Complimentary and Alternative Medicine (NCCAM) and published in the New England Journal of Medicine​, involved 399 college students.

To test the herbal's preventative properties, the researchers began administering extracts of echinacea angustifolia​ or a placebo to some of the volunteers seven days prior to rhinovirus infection.

A second group received echinacea or the placebo at the same time as infection, to determine ability to alleviate symptoms. The symptoms of both groups were observed for five days following infection.

The researchers found that the administration of echinacea had no effect on either rates of infection or the severity of symptoms, leading them to conclude that "extracts of E. angustifolia root, either alone or in combination, do not have clinically significant effects on infection with a rhinovirus or on the clinical illness that results from it".

Three extracts of E. angustifolia​ root were used in the study in 1.5ml doses (equivalent to 300mg of dried powdered root) administered three times a day.

However the American Botanical Council said that the fact that the extracts were made in a university laboratory and are therefore not commercially available to consumers was a major drawback of the study.

Founder and executive director Mark Blumenthal noted that E. angustifolia​ extract is no longer as popular in commercial preparations as it once was, as responsible members of the industry have moved away from using wild plants in favor of sustainable sources. E. angustifolia​ is harder to cultivate than two other varieties (E. pallida and E. purpurea), which are now more common on the North American market.

The dosage used also raised questions.

"It would have been optimal if this trial had tested the echinacea preparation at more frequent and/or higher doses,"​ said Blumenthal.

"Many clinicians who recommend echinacea for treatment of upper respiratory tract infections related to colds and flus 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's concerns were echoed by Michael McGuffin, president of the American Herbal Products Association.

"I'm not sure I would call this a 'placebo versus placebo' test,"​ he said, "but it is not unlike taking one-third or less of the dose of cough syrup and wondering why you are still coughing. The standard dosage for dried E. angustifolia root used at the onset of a cold is well established at 3 grams per day or more and this study used less than 1 gram."

The dosage level was chosen because it corresponds to that set by the German government, which carried out research into various types of echinacea in the early 1990s.

Despite the drawbacks, the study's conclusion that echinacea is ineffective has already been widely reported in the international consumer media.

Nor is it the first time that doubt has been cast of echinacea's efficacy. A University of Wisconsin study published in the Annals of Internal Medicine​ in 2002 found that 1g of unrefined echinacea or echinacea root, taken six times a day on the first day of illness and three times a day thereafter, had no effect on 150 students with colds.

Another, also published in the Annals of Internal Medicine​ in 2003, reported no effect on severity of symptoms and the time taken to recover from a cold in a trial involving 120 adults, who were given 300 mg of an echinacea juice preparation or a placebo each day from the first sign of a cold.

Even so, the industry associations are wary of drawing too much from the latest findings:

"This is not a definitive trial on the efficacy of echinacea, nor should the results be generalized to echinacea preparations widely available,"​ said Blumenthal.

McGuffin said: "It may be that the only fair and useful conclusion from this study is that consumers choose a reputable brand of Echinacea and use it at the right dose."

As we have seen in the case of vitamin E this year, negative reporting can have a serious effect on sales, whether or not the study methodology stands up to scrutiny. Leiner Healthcare and GNC have both experienced falling vitamin E sales since the publication of a widely-criticised meta-analysis in the Annals of Internal Medicine​ last November.

Total sales of echinacea products in the United States have been on the decline since 1999 when retail sales were $247.3 million, according to Euromonitor. After dropping in value each year since then, the product only generated $173.2 million in 2004.

In the Netherlands, sales of the product have gradually increased each year but in Germany sales hit a low during 2000-2002 before climbing again to reach $107.4 million last year.

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