Defining alternative medicine is notoriously difficult, with some practitioners refusing to accept there is anything alternative about such therapies in the first place.

For some, it is simply medicine that has not been proven to the clinical standards of modern western medicine.

For others, it consists of undervalued therapies that have been used successfully for millennia.

Nevertheless, medical bodies have sought to establish a workable definition - some to determine which areas need more research, others to guide doctors on what they should and should not offer patients.

Difficulties

The US has the most thorough definition.

A recent European Commision report says the accepted definition in the US is: "A broad domain of healing resources that encompass all health systems, modalities and practices, and their accompanying theories and beliefs, other than those intrinsic to the politically dominant health system of a particular society or culture in a given historical period.

"It includes all such products and ideas self defined by their users as preventing or treating illness or promoting health and well-being.

"Boundaries within complementary and alternative medicine and between complementary and alternative medicine and the domain of the dominant system are not always sharp or fixed."

European view

The EC-sponsored group that produced the report shied away from any such all-encompassing definition, and simply defined it as those areas of medicine not covered by the medical syllabus.

This, however, is far from satisfactory as many medical schools now offer modules on homeopathy, acupuncture or other alternative medicines.

Dr Jonathan Monckton, director of the UK Research Council for Complementary Medicine, said the growing inclusion on medical courses was because of a general feeling that future doctors should have some understanding of the field.

He says alternative medicine is often better considered as complementary medicine, as much research shows people use them alongside conventional western medicine.

Regulation

Another problem in defining the field is the lack of regulation in many areas - so while conventional medicine can only be practised by a doctor who can prove they have been to medical school and passed all their exams, in many cases anyone can call themselves an alternative practitioner and set up shop.

This is, however, changing. The UK Government has introduced legislation to force chiropractors and osteopaths to register with a statutory body, meaning they cannot practise unless they can prove they are qualified.

In the smaller disciplines of homeopathy and yoga, voluntary regulation is preferred, with professional councils accounting for the competency of practitioners.

Professional and statutory accountability ensure that practitioners are competent, not that the medicine works, but increased regulation brings the therapies more into line with conventional medicine.

Evolving science

Dr Monckton says that whichever way one looks at the area, it is difficult to draw a firm line.

"It's a process of evolution so what is yesterday's fringe is today's alternative, tomorrow's complementary and ultimately it becomes conventional," he said.

"For example - take dentistry. At the turn of the century, dentistry was complete fringe medicine, but look at it now - wholly conventional."