Throughout recorded history, people of various cultures have relied on what Western medical practitioners today call alternative medicine. The term alternative medicine covers a broad range of healing philosophies, approaches, and therapies. It generally describes those treatments and health care practices that are outside mainstream Western health care. People use these treatments and therapies in a variety of ways. Alternative therapies used alone are often referred to as alternative; when used in combination with other alternative therapies, or in addition to conventional therapies they are referred to as complementary. Some therapies are far outside the realm of accepted Western medical theory and practice, but some, like chiropractic treatments, are now established in mainstream medicine.
Worldwide, only an estimated ten to thirty percent of human health care is delivered by conventional, biomedically oriented practitioners ("Fields of Practice"). The remaining seventy to ninety percent ranges from self-care according to folk principles, to care given in an organized health care system based on alternative therapies ("Fields of Practic"). Many cultures have folk medicine traditions that include the use of plants and plant products. In ancient cultures, people meticulously collected information on herbs and developed well-defined herbal pharmacopoeias. Indeed, well into the twentieth century much of the pharmacology of scientific medicine was derived from the herbal lore of native peoples. Many drugs commonly used today are of herbal origin: one-quarter of the prescription drugs dispensed by community pharmacies in the United States contain at least one active ingredient derived from plant material ("Fields of Practice").
Twenty years ago, few physicians would have advised patients to take folic acid to prevent birth defects, vitamin E to promote a healthy heart, or vitamin C to bolster their immune systems.