Echinacea

[Spoon]

Under a Microscope

Scientists are taking a closer look at the super-popular supplement.

What it is:
Echinacea is the second-most popular botanical supplement in the United States. Native Americans used the roots of this herb to treat infections and wounds. Today it’s widely touted as an immune booster and infection fighter, especially against upper respiratory infections, such as the common cold and flu. In addition, certain compounds in echinacea may block inflammation. Three echinacea species are used in supplements: Echinacea purpurea, E. angustifolia and E. pallida. But according to the National Center for Complementary and Alternative Medicine, the one most widely used, E. purpurea, is thought to be most potent.

Where to Get It:
As a dietary supplement, echinacea is sold in a variety of forms, including capsules, tablets, tinctures and extracts. Certain herbal teas, such as Celestial Seasonings Echinacea Complete Care, contain it too. Some products contain the plant’s root, while others use the stem, leaf or flower. To treat colds and other upper respiratory tract infections, the usual dose for adults is 500–1,000 mg of powdered echinacea (tablets or capsules) taken three times daily for five to seven days, or 300 mg of extract taken three times daily.

Evidence so Far:
In studies to date, echinacea does not seem to prevent colds or other infections. The evidence is mixed on whether the supplement can help treat these conditions if taken when symptoms first start. Several studies have found that echinacea may shorten the duration of a cold or reduce the severity of symptoms, but those studies were generally small and poorly designed. A large, well-designed study in adults (New England Journal of Medicine, July 28, 2005) found no benefit, but it used E. angustifolia, which is generally not considered the most powerful species of the herb. A rigorous study in children ages 2–11 (Journal of the American Medical Association, December 3, 2003) also failed to find any positive effects.

The Jury’s Still Out:
One reason study findings are so contradictory is that various preparations of echinacea have been used, and some may be more effective than others. Researchers are currently trying to sort out which plant species, plant parts and compounds may have the strongest therapeutic properties. For now, the research on echinacea’s ability to fight upper respiratory infections is “all over the board,” says Jerald Foote, Ph.D., R.D., assistant professor of nutrition at the University of Arkansas and an echinacea researcher. “It’s a question mark.”

Bottom Line:
If you choose to try echinacea, your best bet is to take it at the first sign of symptoms. “Overall, echinacea appears to be relatively safe,” says Foote. The most common side effect is gastrointestinal problems. But if you have allergies, take note: Echinacea may cause a rash, itching or breathing problems, especially in those allergic to ragweed, chrysanthemums and other plants in the daisy family. Children are especially likely to develop a rash, so talk to your health care provider before giving echinacea to a child. Foote also recommends avoiding echinacea if you have a condition that affects the immune system, such as rheumatoid arthritis, lupus or multiple sclerosis.