Popular diet supplements come up short

It's not good news for users of echinacea, black cohosh, and freeze-dried green-lipped mussel.

Millions of people may be buying them to combat the ills of conditions as diverse as the common cold, hot flushes and arthritis, but the latest evidence raises questions about just how effective they are.

Echinacea, used by many people trying to prevent the common cold or ease its passage, is the latest to be found wanting.

"The latest study on echinacea, one of the best ever conducted, found it was not effective for prevention of the common cold or for treating the symptoms. In other words, it doesn't work," says Professor Edzard Ernst, director of complementary medicine at Exeter University, whose study on the green-lipped mussel supplement has found little consistent evidence for its use as a rheumatoid or osteoarthritis treatment.

In the United States, a study has found that black cohosh, another of the big hitters, is no better than a placebo for menopausal hot flushes.

"Regrettably, we found that it has little potential to play an important role," says lead researcher Dr Katherine Newton.

Health supplements such as echinacea and black cohosh are big business. In Britain, one in five people use them at some time, and almost half of women in their 50s regularly pop one or more. Those suffering from serious and chronic illnesses, including cancer, diabetes and arthritis, are also turning to supplements.

But while some work, the data for most is conflicting or doubtful. There is also concern about safety.

- INDEPENDENT