Call it "alternative," "complementary," "integrative" or "holistic" medicine. Whatever name you choose, such nontraditional therapeutic practices as acupuncture, homeopathy and yoga have become increasingly prominent and provocative parts of the U.S. medical landscape. An estimated 50% of all Americans turn to some type of alternative therapy; three-quarters of U.S. medical schools offer courses in the subject; and even flinty-eyed health insurers are starting to pay for visits to your local herbalist or naturopath.
This shift reflects a growing public yearning for gentler, less invasive forms of healing. But unconventional potions and practices afford rich opportunities for quackery. Health-food magazines and...