IT'S A controversial field of medicine dismissed by some as quackery - but now a new book claims to reveal which complementary therapies are backed by scientific evidence that they really do work.

A review of more than 10,000 studies found that echinacea and melatonin are among those with proven benefits, but the jury is still out on claims for some popular remedies, such as green tea.

Professor Jayney Goddard, president of the Complementary Medical Association (CMA), who edited the book, said that she had been surprised by the evidence for some of the treatments.

"A real old wives' tale, which is taking hawthorn for the heart, is actually borne out in trials," she said. "With complementary medicine a lot of detractors will say there is no evidence - in actual fact if they took the time to look, there is tonnes."

The newly published encyclopedia gathers evidence on complementary medicine based on double-blind, placebo-controlled studies, regarded as the best assessment of whether a treatment is effective. However, one problem is that this type of study is difficult to carry out on therapies prescribed on an individualised basis, such as acupuncture, or homeopathy.

Another reason for a lack of research in the field of complementary medicine, Goddard explained, was that there is little incentive to invest in researching remedies which cannot be exclusively manufactured by a drugs company.

"You can't patent a herb, you can't patent massage and you can't patent homeopathic remedies or a vitamin," she said. "The people who actually do the large-scale medical trials are the pharmaceutical companies, but if they can't get a product out of it, why should they bother?

"Some people hold a view of big, bad pharmaceutical companies', but actually they are just companies that have a legal duty to their shareholders to make a profit."

Recent research revealed that people in Britain now spend up to £191 million on complementary therapies annually, an increase of 32% in the past five years. The use of these remedies is still hotly debated. While supporters include Prince Charles, some of the UK's most eminent doctors last year called for a halt on NHS spending on treatments such as homeopathy.

A spokeswoman for independent science body the Royal Society said it was vital that complementary and alternative medicines were properly tested and patients did not receive "misleading information" about their effectiveness.

"Furthermore, NHS provision for complementary and alternative medicines, as for conventional medicines, should be confined to treatments that are supported by adequate diagnosis together with evidence of both effectiveness and safety," she added.

Dr Mairi Scott, chairwoman of the Royal College of General Practitioners in Scotland, said there were some complementary therapies patients put "great faith" in: "Homeopathy is available within the NHS, although it is a pretty scarce resource. I think there is not a lot of evidence for it, but there is a recognition that some patients feel the benefit from it sometimes.

"Other therapies such as reflexology are more about relaxation and coping strategies and are not what I would call therapies in the traditional sense."

She added: "As long as the patients have the information from people who deliver these services and they operate within a safe environment, then we wouldn't have comment one way or the other."