THREE DOZEN doctors-in-training recently sat in a conference room in Tucson. Arizona sunshine streamed through open French windows. On the floor were votive candles and peacock feathers, symbols of healing. It was the closing ceremony in a month-long course at the Centre for Integrative Medicine at the University of Arizona, promoting the notion that doctors should use alternative treatments alongside conventional ones. Speaking to the students was Andrew Weil, a doctor and campaigner who heads the centre.

Dr Weil is a diminutive Santa Claus with a not-so-diminutive brand. He writes books and sells products (such as the Dr Andrew Weil for Origins™ Mega-Mushroom Skin Relief Soothing Face Lotion, for $61). Profits go to his foundation. On this occasion he was in his role as teacher, explaining the importance of nutrition in keeping patients well. That is a doctor's task, he said, not merely treating the sick.

Few in mainstream medicine would disagree with such an approach. But Dr Weil continued by saying that evidence-based medicine, at its worst, “is exactly analogous to religious fundamentalism.” He urged the students to promote integrative medicine. Together, they would be the future of American health care.

They are well on their way. By one recent count four in ten American adults use some form of alternative therapy. If Dr Weil's flourishing business and other programmes are any indication, these will grow even further. For six decades double-blind, randomised, placebo-controlled trials have helped doctors to sort science from opinion and to sift evidence from anecdote. Now those lines are blurring.

The evidence for alternative treatments varies wildly. Some herbal remedies broadly meet the test of mainstream medicine. St John's wort has antidepressive effects (though quite how it works is not completely clear). Chinese herbs may improve chemotherapy for colon cancer. Acupuncture can relieve nausea and some types of pain—though for other ailments it seems no more effective than a placebo, according to Edzard Ernst, who led the study of alternative medicine at Exeter University. Homeopathy is more controversial. Believers say substances which in large quantities may cause symptoms of illness can cure them in highly diluted form, thanks to an imprint left on the water. Sceptics deride both that claim and the principle behind it.

An example is Oscillococcinum, a homeopathic treatment for flu symptoms made with extract of duck heart and liver. Once diluted 100-fold—with the process then repeated another 200 times—it purportedly gains healing properties. Boiron, a French firm that makes this and other such products, had revenues of €523m ($681m) in 2011. Whatever the scientific arguments (or lack of them) for such treatments, the commercial ones are striking.

Powerful supporters have helped the cause. King George VI helped to ensure that homeopathy would be part of Britain's newly created National Health Service (his grandson, Prince Charles, is also a fan). Royal Copeland, an American senator and homeopath, saw to it that the Food, Drug and Cosmetic Act of 1938 authorised homeopathic products. Sixty years on another senator, Tom Harkin, helped to set up the National Centre for Complementary and Alternative Medicine (NCCAM) at the world's leading medical-research outfit, the National Institutes of Health (NIH).

Small pills

The $1.5 billion that taxpayers have devoted to NCCAM has brought meagre returns. In 2009 Mr Harkin said it had “fallen short” and bemoaned its focus on “disproving things” rather than approving them. But it has spawned a new generation of research outfits. The University of Maryland's Centre for Integrative Medicine has received $25m from the NIH for research. Separately it offers treatments such as reiki, in which a healer floats his hands over the patient's body.

In 2003, with NIH funding, Georgetown University created a master's degree in alternative therapies. The University of Arizona offers training in them for medical students and a two-year distance-learning course for doctors and nurses. The Consortium of Academic Health Centres for Integrative Medicine now has 50 members.

Such trends have vocal opponents. In Britain and Australia, horrified scientists are fighting hard against the teaching of alternative therapies in publicly funded universities and against their provision in mainstream medical care. They have had most success in Britain. David Colquhoun, a pharmacology professor at University College London, has shamed some universities into ending alternative courses. The number of homeopathic hospitals in Britain is dwindling. In 2005 the Lancet, a leading medical journal, analysed the evidence and declared “the end of homeopathy”. In 2010 a parliamentary science committee advised that “the government should not endorse the use of placebo treatments including homeopathy.” But the NHS still provides it, albeit to the modest tune of £4m ($6.3m) a year.

A similar push in Australia has proved futile so far. In January a group of dismayed academics, doctors and scientists urged universities to renounce courses in alternative medicine. The universities' leaders have yet to budge, although a leaked paper from the National Health and Medical Research Council describes homeopathy as “unethical” and baseless.

The future for the alternative-therapy industry looks particularly bright in America. NCCAM continues to pay for research. Josephine Briggs, its director, says she is neither for nor against alternative treatments; she just wants to test which ones work and which do not (she is also interested in the effect of medical rituals). But Steven Novella, a vocal critic at Yale University, argues that the centre's very existence fuels the cause. “People say, ‘The government is researching that, so it has got to be legitimate',” he complains.

Supporters of alternative medicine have two additional forces in their favour. Conventional health care has some clear failings. As Dr Weil points out, America's health-care system excels at treating sick patients but is miserable at keeping them well. The pharmaceutical industry struggles to create good, long-term treatments for pain and other chronic conditions. Many doctors are hurried or come across as unsympathetic. Alternative practitioners spend time with patients, asking about not just their medical histories but their lifestyles. They may emphasise nutrition and exercise. Many such treatments, especially the hands-on ones, are soothing. It is unsurprising if patients feel better.

Second, arguments that insist on evidence and scientific rationales work only with those who think that these are all that matters. Many providers of alternative therapy say it is inherently unsuited to double-blind randomised trials.

The study of placebos does not jar with orthodox medicine. Harvard University (which employed Henry Beecher, inventor of the randomised trial) has now created a new programme in “Placebo Studies and the Therapeutic Encounter”. Ted Kaptchuk, its director, is studying how patients respond to sham treatments, as well as the importance of patient's faith in a treatment. In a paper in the New England Journal of Medicine last July he described an experiment with asthma inhalers. The real ones improved patients' lung function by 20%, compared with 7% for the alternatives: a dummy inhaler or acupuncture. But patients judged the effectiveness of the three therapies to be about the same.

The worries about the ethics of prescribing a placebo are real. But so are fears that alternative therapies may do harm—for instance, by tempting patients to shun real medicine. Steve Jobs, the founder of Apple, died from cancer last year after having first favoured acupuncture and fruit juices over conventional treatment. Misplaced faith has its costs.