Gwyneth lives by it, and thousands of others as well, but are they being taken for a ride?

Alternative medicine was once regarded as little more than another mystery of the Orient. Few Westerners had faith in the healing properties of tigers' testicles, ground rhino horn or in the limb-bending contortions of the yogics.

Yet, thanks partly to the efforts of Prince Charles, millions are turning to radical therapies for ailments ranging from mild aches and twinges to serious diseases. A third of cancer patients, for example, now use herbs, homeopathy or mineral supplements.

But do they actually work? So far there is a distinct lack of scientific evidence either way, but that has done little to hinder the extraordinary growth of the treatment industry.

Expenditure on treatments that include acupuncture and reflexology is expected to increase by pounds 70m in the next four years, a boom led by consumers in their 30s and early 40s and promoted by the likes of Madonna, Cherie Blair and Gwyneth Paltrow (main picture, left). In the UK, pounds 130m a year is spent on non-prescription herbal remedies.

One in 10 Britons are said to be regular users of non-standard treatments. One in five have done so in the past. The range on offer is extraordinary, from the proven herbal benefits of St John's Wort, which can help relieve depression, to the faintly bizarre.

Mrs Blair was reported recently to be interested in electronic gem therapy which claims it can combat ailments by increasing blood flow and boosting the biological activity of organs.

There is no mention of that in a new patient guide to complementary medicine, backed by the Prince of Wales and published next week by his Foundation for Integrated Health. The 45-page book, distributed free to all GP surgeries, will offer advice on therapies now judged mainstream, including acupuncture, aromatherapy, chiropractic, cranio-sacral treatment (involving head massage), herbal medicine, reflexology and yoga therapy.

Yet serious questions remain, with doctors warning that proper regulation is required to ensure that people are not being conned or even physically damaged. Plant extracts can be dangerous, particularly if adulterated.

The British Medical Association points out that much complementary medicine has no true track record of providing results and calls for further regulation.

A spokesman for the Royal College of GPs warned that "complementary medicine covers a wide spectrum and there is not the evidence to support the use of some of it".

Herbal treatments are coming in for particular scrutiny as the drugs involved are powerful, and could cause serious damage to such important organs as the liver and the kidneys.

Some, including hawthorn for helping reduce the risk of heart attacks, have been proven to help, in the correct dosage. Others have not.

There is always the risk of adulteration, particularly from abroad, with the risk that plant extracts will include heavy metals or other forms of poison.

Next week ministers will announce plans to place both herbal practitioners and acupuncturists under a new regulatory system, which will require them to undergo training and hold approved qualifications.

The Prince of Wales's Foundation for Integrated Health has been given pounds 900,000 over the next three years to persuade the other main therapy groups to introduce self- regulation. But will it work?

According to Professor Edzard Ernst, from the Peninsula School of Medicine at the Universities of Plymouth and Exeter, and the country's leading authority in the field, a scheme of approved operators will certainly offer protection against the worst.

Yet he believes that there is limited value in regulating things with no proven value. "If you regulate nonsense, you tend to end up with regulated nonsense," he said.