Close detail of an echinacea flower, now proved as a cold-busting immune stimulant.

Credit: iStockphoto

Related articles

• Lack of sleep raises common cold risk
• Common cold erodes memory
• Antioxidants may not protect against cancer
• Winter weather really does spread flu
• Death by vitamins

PARIS: Echinacea, a medicinal herb that came to prominence thanks to its use by Sioux Indians, can more than halve the risk of catching a cold, a wide-scale study has confirmed.

Taking echinacea supplements can reduce the risk of a cold by 58 per cent and may also shorten the duration of a cold by almost one and a half days, according to the paper, published in the July issue of the British journal The Lancet Infectious Diseases.

The study is a detailed 'meta-analysis' comparing the outcome of 14 published trials using echinacea. One of the trials combined with echinacea with vitamin C, which showed the two together reduced the incidence of a cold by 86 per cent.

The analysis was led by University of Connecticut, U.S., pharmacist Craig Coleman.

Traditional remedy

Echinacea is a term for nine, related daisy-like plant species that are native to North America and feature in the traditional medicine of the Sioux and other Plains Indians as remedies for infection, snakebites and rabies. Other names for the plant are black sampson, Kansas snakeroot and purple coneflower.

Coleman's team said they had counted more than 800 products containing echinacea, which come in the form of tablets, extracts, fresh juice, tincture and tea.

Three of the nine species are commonly used (Echinacea purpurea, E. angustifolia and E. pallida), and different parts of the plant are used for different products.

The authors say it is still unclear how echinacea appears to stimulate the immune system against the cold virus. Its three major ingredients are alkamides, chicoric acid and polysaccharides, but it is unclear whether these work by acting separately or together, or with the help of other constituents.

And the authors sound a word of caution, saying more work needs to be done on the plant's safety before doctors can recommend echinacea as a standard option for preventing or treating the common cold.

This is “a significant step in our battle against the common cold," commented professor Ronald Eccles, director of Cardiff University's Common Cold Centre in Wales. "Harnessing the power of our own immune system to fight common infections with herbal medicines such as Echinacea is now given more validity with this interesting scientific evaluation of past clinical trials.”