It has now been three decades since `evidence-based medicine' or EBM became formalised and taught as the correct way to practice medicine. But a paper published earlier this year in the American Medical Association's Archives of Internal Medicine shows just how uncertain the field remains.

Studies from 1991 estimated that only 15% of medical interventions practiced by doctors were supported by solid scientific evidence.

More recently it has been estimated decisions made by doctors using such science ranges widely from 11% to 70%. "Hardly ringing endorsement of medicine as science" says Dr Wayne Jonas, author of the AMA's paper `Scientific Evidence and Medical Practice'.

Even when EBM does exist it often only applies to a narrow range of patients. A 1994 study claims that many, if not the majority of procedures carried out under modern medicine have "little if any scientific basis" (Maynard).

Rather it turns out that doctors most commonly rely on `mindlines' when deciding what kind of treatment might best suit a patient - essentially their best guess based on previous experience coupled with what colleagues currently believe.

That's why such a broad variety of different treatments may be offered to patients suffering the same aliments.

One example cited in a study published in The Journal of The Royal Society for the Promotion of Health was on prostheses for hip replacements: 30 different types of cemented and 35 types of uncemented prostheses were used in English hospitals, most of which had not been investigated.

Other studies revealed striking variations in surgical interventions for prostatectomy, hysterectomy, tonsillectomy and carotid endarterectomy.

Wrote the study's high ranking nursing professor authors: "If orthodox medicine is practiced on the basis of scientific evidence, as is claimed by its practitioners, such variations defy explanation," with them adding, "... in view of such admissions, it seems incredible that medical practitioners have been trying to undermine the practice of complementary therapists because of their lack of an appropriate evidence base."

This lack of EBM has been a criticism long levelled at holistic or natural health practitioners. Yet just as it's being revealed how little of modern medicine actually relies on solid science, the global popularity of holistic treatments is itself driving a body of evidence proving their effectiveness.

Just a few examples:

Randomized controlled trials showing aromatherapy and massage can be effective in reducing physiological and psychological stress after cardiac surgery (Jackson, 1995)

Homeopathy and acupuncture being effective treatments for psoriasis (Liao and Liao, 1992)

Massage effectively reducing anxiety and tension (Wilkinson, 1996)

Reflexology useful in managing premenstrual symptoms (Olsen and Flocco, 1993)

Interest in such natural based therapies has been growing exponentially - some estimates say at around 11% annually. A 1991 UK study showed that number of alternative practitioners was growing at a rate of five to six times that of medical doctors.

Certainly the public are visiting holistic therapists in increasing numbers. A 2007 National Health Interview Survey conducted by the US's Centre for Disease Control and Prevention found four out of 10 American adults had used such therapies in the past 12 months.

Other studies have shown around 90% of the population of the United Kingdom had used at least one form of complementary therapy or another.

In Europe, those figures ranged from 24% in Denmark to 49% in France (in Denmark cost of complementary treatment is reimbursed by private and state health insurance).

Among factors found to be driving this global natural health trend is the lack of side effects from such treatments; the fact that complementary and alternative medical health (CAM) practitioners look to treat the whole person rather than just the symptoms and that such therapies empower patients by encouraging them to participate and take control over their own health issues.

A 1997 UK study showed vast majority of users were happy with such holistic treatments - 90% felt quality of life had improved as a result and 60% would use natural health practitioners again, despite the often considerable costs involved.

Perhaps even more telling is just how public support of CAM therapies is driving doctor behaviour.

In New Zealand, a 2002 Health Survey found 12% of adults visiting a complementary health practitioner that year had been referred by their own general practitioner.

In addition other studies discovered:

A 2003 study of Wanganui city general practitioners found 92% had referred patients to CAM practitioners and 80% had contact with at least one CAM practitioner. The doctors rated their confidence highest in acupuncture, chiropractic, hypnosis, aromatherapy and Rongoa Maori (traditional Maori medicine) treatments.

In a study of 249 Auckland GPs, 171 (68.7%) referred patients for CAM treatments. The study found younger doctors were the most likely to refer patients to CAM practitioners. The Auckland study found 30% of GPs surveyed practiced one or more form of CAM - most often used to treat musculoskeletal and chronic pain problems.

The most common reason given by New Zealand GPs for referral to CAM practitioners was `failure of conventional medicine'.

At the forefront of evidence-based approach to natural health care in New Zealand is Phillip Cottingham, a 30-year veteran of the natural health industry and founder of the leading training institute, Wellpark College of Natural Therapies which trains domestic and international students.

He says the oft cited criticism that natural medicine lacks scientific evidence is "the biggest urban myth of our times".

A strong advocate of the `integrated medicine' approach - effectively health treatments that integrate the best available from orthodox and natural medicine - Phillip is the driver behind a new research unit in natural medicines being set up in New Zealand.

The unit, to be based in Auckland, will involve a full time research fellow who will be collating and making evidence-based natural health information freely available to the international public via website (www.wellpark.co.nz).

What is clear is that doctors around the world who are open minded enough to refer patients to CAM practitioners are happy with the outcome.

In Germany, 58% of accredited general practitioners polled in a 1993 study declared they preferred complementary to orthodox medicine - and all but three of the practitioners sampled accepted the value of complementary medicine.

In 1981, despite a ruling by the British Medicine Association that clearly discouraged GPs from connection with practitioners of complementary therapies, 10% of patients visiting natural health therapies had been recommended to do so by their doctors.

According to the Journal of the Royal Society for the Promotion of Health survey `Complementary therapy: complement or threat to modern medicine?' nurses and midwives have lost no time in keeping up with public demand either and have been training in such natural therapies.

The survey found more than half of the nursing practitioners surveyed used CAM therapies in their work: 80% of those using such therapies had undergoing training and 92% who had not used such therapies were prepared to do so (Trevelyan 1996).

"Despite constant criticism of complementary therapy by some medical practitioners, 65% of hospital doctors believe that such therapies have a place in the mainstream of medicine," wrote report authors.

By 1993, the British Medical Association had changed years of attacking and attempting to discredit complementary medicine by conceding there as a place for it in health care - provided doctors retain overall control of treatments received by their patients.

More than two dozen medical schools in the US now offer electives in alternative medicine.

(for breakout information box)

What are CAM therapies?

Whether you call it holistic, natural, alternative or complementary therapies there are a huge number of treatments available.

These include:

Acupuncture

Herbal medicine

Naturopathy

Nutritional therapy

Homeopathy

Ayurveda

Traditional Chinese medicine

Hypnotherapy

Spiritual healing

Chiropractic treatments

Osteopathy

Alexandra technique

Reiki

Touch for health

Aura Soma

Bioelectromagnetic therapies

Aromatherapy

Massage

Flower essences

Rebirthing

Maori medicine

Yoga

Meditation

Chelation therapies

One of the best ways to find a reliable practitioner is word-of-mouth.

When visiting a holistic practitioner don't be afraid to ask to see their relevant qualifications and ask what experience they've had treating people with your particular health issue.

Most modalities have national associations that oversee practitioner qualifications.