Echinacea is a popular herb used to reduce the symptoms and duration of the common cold. According to the Nutrition Business Journal, Americans spent an estimated $155 million on echinacea in 2004.
Researchers led by Ronald Turner, MD, of the University of Virginia School of Medicine, however, recently published findings showing that echinacea had no effect on preventing colds or reducing the severity and duration of cold symptoms.
The study was funded by the National Center for Complementary and Alternative Medicine, a branch of the federal National Institutes of Health. The study took more than three years and cost $2.2 million.
Although the media has been quick to conclude that echinacea is useless or ineffective, there are a couple of important points to be aware of:
The study has been criticized for using too low a dose of echinacea.
The dose of echinacea used in the study (equivalent to 900 mg dried echinacea root) was lower than what is commonly recommended. For example, Canada's Natural Health Products Directorate suggests a dose of up to 3 g per day, which is more than 3 times the amount used in this study.
Herbalists often recommend a total daily dose of 3 or more grams of echinacea per day at the first sign of cold symptoms. It's usually taken in divided doses, with a dose every 2-3 hours. After one to two days, the dose is usually reduced and continued for the following week. Had this study looked at these doses, the results may have been different.
This study used one particular type of echinacea that hasn't been as well researched -- the root of a species called Echinacea angustifolia.
Echinacea purpurea, another species of echinacea, has been shown to be effective in other studies, particularly preparations made from aerial parts (the leaves, stem, and flowers). This study used echinacea angustifolia roots.
Germany's Commission E, an authoritative expert herb panel which guides modern drug laws in Germany, only recommends echinacea purpurea aerial parts and the roots of another species, echinacea pallida. They don't approve angustifolia.
A smaller study led by Dr. Steven Sperber of Hackensack University Medical Center in New Jersey used echinacea purpurea aerial parts. Although echinacea didn't prevent infection (which may be due to the lower dose used), they found that 58% of people taking an echinacea purpurea extract made from aerial parts developed cold symptoms, compared to 82% of people taking a placebo.
Two echinacea preparations made from aerial parts of echinacea purpurea are Echinaguard by Nature's Way and Echinaforce by Vogel. These proprietary formulas have been used in research studies.