"I know that complementary medicine works," Dawson says. "The main reason I came to this conference is to gather scientific information to support what I believe."

The question remains, however, how scientifically unproven therapies should be tested.

"The reductionist model is not the best way," says Andrew Weil, a professor of medicine at University of Arizona and well-known author of books on nutrition and integrative medicine.

"The current model does not allow for non-physical causes for physical events," he says.

He criticizes scientific studies that attempt to isolate the single active component of herbal medicines. He says such studies do not appreciate the full effect that all the components the medicines have.

Hummel says he agrees, and says in many cases, technology to test non-traditional therapies is not yet available.

For example, the qi, or energy that is part of traditional Chinese medicine, has not been detected with traditional scientific methods.

"There will be a point in time when we can detect these things," he says.

Eisenberg echoes the idea that more research is needed, quoting Carl Sagan, a famous science philosopher that "exceptional claims require exceptional evidence."

"If we all commit ourselves to figure out what is useful, useless, safe, and unsafe, we will create a better model of health care for the next generation," Eisenberg says.