The growth of alternative therapies, believed to be worth $14bn (pounds 8.8bn) in the US alone, belies the fact that many treatments have been scientifically discredited, said Barry Beyerstein, of Simon Fraser University in British Columbia, at the American Association for the Advancement of Science conference in Seattle.
Dr Fraser said: "A fertile climate for quackery has been created by the generally low level of scientific literacy among the population, and vigorous marketing of extravagant claims by so-called healers, which appeal to wishful thinking."
Sometimes, alternative medicine practitioners twist the reporting of scientific tests which have carried out on their therapies in order to give a distorted picture of their effectiveness, said Saul Green, of Zol Consultants in New York.
"After 15 years of studying and searching, I have not found one 'alternative' treatment for cancer that I could endorse," said the former cancer researcher.
"I realised that the proponents of these therapies depended on the fact that patients were deeply impressed with the printed word ... Advertising, not medical science, was the life-blood of these dubious methods."
He contrasted the situation today with that in 1903 and 1938, when investigative journalism exposed the frauds being carried out by the patent medicine industry.
Nowadays, he said, alternative therapies control so much money that they can lobby government to restrict antagonistic reports.
Robert Park, of the department of physics at the University of Maryland, said that "many of the claims made for alternative therapies violate the basic laws of physics." Homoeopathy relies on a "serious misunderstanding" of chaos theory, while the suggestions of "biofields" which extend beyond the body have no basis whatsoever in physics.
Instead, he noted, Occam's Razor was surprisingly effective: "Experimental evidence offered in support of such claims inevitably has a simpler explanation".
Ursula Goodenough, professor of biology at Washington Univer-sity, said: people should regard the claims of alternative therapies with "scepticism and alarm".
"Humans have a huge problem with alienation, and belief in alternative medicines is a vacuum that people move into," she said.
"An upshot of alternative medicine is the fostering of 'anti-science' feeling. The problem is not the nice person in the health store who believes what's being sold is healthy. Rather, it's the industry built on pseudo- science that preys on hopeless people.
"It fills me with moral outrage. Scientists carry an obligation to protest [against] such abuses of scientific knowledge."Reuse content