Echinacea, a herb widely used to fight the sniffles, helps reduce the risk of getting thecommon coldand shortensits duration, a new review suggests.

In the July issue of the medical journal The Lancet Infectious Diseases, researchers analyzed the results of 14 published trials on echinacea, or purple coneflower. The beneficial effect was seen after combining results from 1,600 participants.

'An analysis of the current evidence in the literature suggests that echinacea has a benefit in decreasing the incidence and duration of the common cold." —Study's conclusion

Echinacea refers to flowers, roots and stems of nine related plants that are native to North America. Extracts are thought to boost the body's immune system.

Taking the supplements seemed to reduce the risk of developing a cold by 58 per cent and shortened duration of a cold by an average of 1.4 days, the team reported.

"An analysis of the current evidence in the literature suggests that echinacea has a benefit in decreasing the incidence and duration of the common cold," the review concluded.

In one study, taking echinacea along with vitamin C reduced cold incidence by 86 per cent, comparedto 65 per cent for the herb alone.

Previous studies looking at the anti-cold effects ofechinacea have shown opposite results. In 2005, a review published in the New England Journal of Medicine on more than 400 people concluded the herb was useless for cold symptoms.

Hundreds ofproducts on the market

The latest review was led by Craig Coleman, a pharmacist at the University of Connecticut.

The plant has three major ingredients, called alkamides, chicoric acid and polysaccharides, but it remains unclear how the herb may stimulate the immune system against cold viruses, Coleman and his colleageus said.

More than 800 products containing echinacea are available, the researchers found. Supplements may contain different parts, or combineechinacea with other herbs that have not been tested.

The study's authors cautioned that clinical trials are needed before doctors can recommend echinacea to prevent or treat the common cold.

Health Canada requires all natural health products be licensed before sale, and to be labelled with an eight-digit product licence number that shows the product has been reviewed and approved by the department for safety and efficacy.

Use ofechinacea is contraindicated during pregnancy and breastfeeding, the department said.People with HIV/AIDS, tuberculosis, multiple sclerosis and autoimmune disorders are advised to consult a health-care professional before using it.

Some earlier small studies were poorly controlled and sponsored by industry, Wallace Sampson, editor of the Scientific Review of Alternative Medicine and an emeritus clinical professor of medicine at Stanford University, said in a commentary accompanying the 2005 review.

Aspokesperson for the supplements industry saidechinacea may be more effective whenits three active components are combined in a specific ratio.

The World Health Organization recognizedechinacea as a cold treatment in 1999.