IF THEY ARE NATURAL, WHY THE CONCERN?

Herbal medicines contain chemicals just like conventional drugs. The fact they are natural does not mean they are not toxic, and some are risky, says Edzard Ernst, of Exeter University, Britain’s first professor of complementary medicine.

Kava a plant-based remedy used for anxiety, was banned a few years ago after it was connected with liver problems.

Others remedies may not be toxic but can interact with prescribed medicines. For example, St John’s Wort - used for depression - interferes with at least 50 per cent of prescribed drugs.

Medical experts also fear that some people may put their lives at risk by relying on complementary rather than sound medical treatment.

Some alternative medicine clinics sell homeopathic protection against malaria, despite clear Government advice that there is no evidence such treatments work Another issue is the variable quality of complementary products.

"There is hardly any quality control of herbal remedies, and they are not nearly as tightly regulated as conventional medicines," says Professor Ernst.

"This means that some, particularly Asian mixtures, can be contaminated, for instance with heavy metals, or adulterated with prescription drugs."

Denis Gore, a Manchester-based community pharmacist who has a special interest in complementary medicine, suggests it is best to buy alternative products from a pharmacy rather than a health food store.