A recent research carried out lately proves that echinacea, one of the most popular herbal remedies, is useless at preventing and treating colds.
The finding, published in Thursday's New England Journal of Medicine, is the latest to show no benefit from the herb, which is widely billed as an immune system booster and promoted by advocates of "natural" remedies as a proven treatment.
The study, led by Ronald Turner of the University of Virginia, tested echinacea on 399 volunteers to determine whether any of three preparations had an active ingredient that reduced the risk of infection or symptoms if an infection took hold.
Three groups were given echinacea extracted with a solvent called supercritical carbon dioxide, 60 per cent ethanol or 20 per cent ethanol for seven days before being exposed to a cold virus via a throat spray. After five days, the proportions that became infected were respectively 89 per cent, 81 per cent and 92 per cent.
Telegraph informs three other groups took placebos for seven days before being infected and then were given echinacea extracted with supercritical CO2, 60 per cent ethanol or 20 per cent ethanol for five days. Their respective infection rates were 90 per cent, 92 per cent and 86 per cent.
A final group took placebos both for seven days before infection and five days afterwards. The control group's infection rate was 88 per cent - showing echinacea had no real preventative effect.
The volunteers were also asked to rate symptoms including sneezing, nasal obstruction, sore throat, cough, headache and chills on a scale of 0-4.
The results suggested that the root had no significant effect on severity of symptoms.
Although the researchers tested the echinacea species originally used by Native Americans in the Midwest and endorsed by WHO, the treatment was no more effective than a placebo.
There are many types of echinacea preparations, so it would be difficult to test them all, Turner was quoted as saying by Reuters. "Our study, however, adds to the accumulating evidence that suggests that the burden of proof should lie with those who advocate this treatment."
In his commentary, Sampson, of the scientific Review of Alternative Medicine, said most of the previous tests that helped build echinacea's reputation "were of small, inadequately controlled studies sponsored by industry."
Turner's study was funded by the National Center for Complementary and Alternative Medicine, a government agency that pays for research largely on the basis of the popularity of the unconventional treatment.
Echinacea extract was originally used by North American Indians to treat a variety of infections and wounds.
In modern times it is widely used for colds, flu and other respiratory infections, as well as earache, acne, wound healing, mouth and throat infections, skin disorders and candida. It is claimed that it works by boosting the immune system.