Marron survived her cancer, but she will never forget the presentation from a naturopath who has been invited to the 2005 breast cancer support group meeting.

"She was just attacking doctors from the beginning to the end, saying they were funded by drug companies and you can't rely on them," Marron, now chief executive of Friends of Science in Medicine, says.

The experience spurred her to spend the next eight years exposing the worst practices in alternative medicine.

Complementary and alternative medicine varies widely, but is often not supported by scientific theory and research.

From multivitamins to acupuncture, it's a growth industry. By some estimates two-thirds of us use some form of complementary or alternative medicine every year - spending up to $1.8 billion.

And national registration has led chiropractors, Chinese medicine practitioners and osteopaths - and, perhaps soon, naturopaths and others - to be registered by the same federal body that covers doctors and nurses.

Universities are running courses and even government funding for treatments has skyrocketed. In 2005 Medicare paid out just over $22,000 annually on chiropractic and osteopathic treatments - last year it paid $15 million.

But Marron wonders if bringing alternative medicine inside the mainstream has brought much-needed oversight, or simply given some operators undeserved respectability. "People are told that chiropractors and osteopaths for example are registered, but they're not told they are self-regulated," she says.

And the self-regulation looks loose.

Even the federally mandated Chiropractic Board of Australia allows chiropractors to make up their annual 12.5 hours of formal education, which they must undertake in order to practise, from known anti-vaccination proponents.

"Once they are regulated that legitimises them, but it comes with a responsibility to consumers, they can't have it both ways," says Marron, who has spent hours trawling through the courses and documenting those promoting unscientific claims.

She is particularly critical of universities for offering courses in alternative medicine, citing a former lecturer at Macquarie University who on her website says she can use naturopathic treatments to ''enhance the efficacy of chemotherapy'', and ''to alter the 'terrain' of the patient to be non-supportive of tumour cells''.

Other lecturers claim to be able to use chiropractic for children with repeat infections or problems breastfeeding.

Macquarie University says it only offers rigorous, high-quality courses. "Our students are taught to understand that science proceeds only on the basis of evidence. They are taught only those techniques that are known through science to be beneficial," a university spokesman says.

But Marron argues that such courses give a veil of respectability to unscientific beliefs. "It's only when you scrape back to look at what is in the courses that you think something is quite wrong," she says.

Simon French has researched the practices of Australian chiropractors and says within modern chiropractic there is a continuum of practice. Some very fringe practices exist at one end and evidence-based practice at the other, according to French, from the school of health sciences at the University of Melbourne.

But he believes the chiropractors' board is trying to bring the profession into the mainstream, by doing things such as commissioning reports on evidence-based practice - a development he calls "promising".

This week the board released a position statement advising chiropractors that vaccination was not in their usual area of expertise, and as such they should avoid giving advice about it.

Yet the practise of some harks back to the oldest traditions of the therapy.

Chiropractic was founded in 1895 by an American, Daniel David Palmer, after what sounds like a miracle. ''A deaf guy got his hearing back when he got his spine adjusted, and that doesn't happen very often, but it happened," says Tony Croke, a national director of the Chiropractors' Association of Australia.

The early chiropractors believed subluxations, or misalignments in the spine, could lead to almost any health problem. As technology advanced and subluxations could not be found using X-rays or other imaging techniques, many chiropractors abandoned the theory.

In 2010 the British General Chiropractic Council announced: "[Subluxation] is not supported by any clinical research evidence that would allow claims to be made that it is the cause of disease or health concerns.'' But the Chiropractors' Association of Australia is still committed to subluxation.

Croke says the concept includes things such as inflammation, stiffness or poor function, which is then thought to impact nervous system function.

"Diagnostic imaging is not particularly helpful for diagnosing [this type of] dysfunction," Croke says.

Chiropractic should be seen as not "curing" problems, but contributing to a healthy, well-functioning body - and identifying a body that isn't. The test chiropractors do on children to identify poor functioning as similar to those "a paediatric neurologist might do", he says.

But the question remains how a painless reduction in joint function, invisible on medical scans, could change the signals sent by our nerves.

Research papers supporting the theory are filled with references backing the claim, but when the Herald examined them, most studied people with chronic pain or arthritis.

Others documented uncontroversial facts about the central nervous system, but did not support the broader claim that a spinal joint with no pain or obvious symptoms could change nerve functions, and lead to asthma, infections or other childhood conditions.

"This is the hallmark of pseudo-science," says Chris Del Mar, a professor of public health at Bond University.

"The way to do it is to churn out lots of this stuff, which is impressive to someone who doesn't understand it and to do it with the imprimatur of the universities.''

Del Mar, like every sceptic of alternative medicine, is keen to point out that he has no trouble with chiropractors who seek to treat musculoskeletal conditions such as back pain. (Although, research reviews have found it is only marginally effective, just no worse than anything else offered for the hard-to-treat condition).

"When they start professing they are paramount and start saying you should do this and not that [medicine] it makes me narrow my eyes," he says.

"It is no longer complementary medicine, it's oppositional."

Marron argues there is also plenty of money to be made in alternative and complementary treatments.

She is a woman on a mission, and now, with Friends of Science in Medicine, she has the support of about 900 doctor-supporters behind her.

"Desperate people will do anything when they are sick," she says.