Of the 10 top-selling herbal dietary supplements in the United States today, 7 were used by Native Americans (Table 1
). Numerous other widely sold herbal supplements, such as black cohosh (Cimicifuga racemosa), blue cohosh (Caulophyllum thalictroides), elderberry (Sambucus species), and juniper (Juniperus communis), were used extensively by indigenous North American peoples. Some pharmaceuticals were originally discovered in the course of investigations of botanicals that were used by Native Americans for medicinal purposes. Examples are taxol, obtained from Taxus brevifolia (Pacific yew tree), and etoposide phosphate, a derivative of podophyllotoxin, which is a constituent of Podophyllum peltatum (May apple or American mandrake) (6, 7). Both are currently used for the treatment of various malignancies.
Plants play an important role in the medical practices of many, if not all, Native American peoples. Thus, plants are used not only in the diagnostic process, but also in the physical and ritual purification procedures that commonly precede ceremonies and in the act of healing itself. Of the >17000 plant species that constitute the North American flora, >2500 members of the vascular taxa and >2800 of all taxa were used—and to some extent continue to be used—for medicinal purposes by various Native American societies (
8). The gathering of information about the use of particular plants as medicine has been in progress for at least a century. The resulting data were compiled in book form in 1986 (
9) and, more recently, in an Internet database (
http://www.umd.umich.edu/cgi-bin/herb). Yet, ethnobotanists continue to uncover additional medicinal plants and uses of the plants already included in these databases (
10–
13).
Specific uses of medicinal plants by Native Americans have been reported and, interestingly, the same plant parts were often used by many different tribes in diverse areas of North America (Table 2). Analysis of the plants used as medicines by the original North American residents showed that the choice of medicinal botanicals was by no means random, but highly selective, as evidenced by the extensive use of some plant families and the virtual avoidance of others (8, 14). Several lines of evidence suggest that Native Americans took botanicals as medicine in the sense that Western science uses that term (15–17). For example, Native Americans used different plant parts for the treatment of various ailments (9), combined several botanicals for specific therapeutic purposes, and recognized toxic plants both as actual poisons and for medicinal purposes (3, 6, 15–17). However, we should emphasize that a spiritual component is also involved in the use of plants for the treatment of particular symptoms, because it is the power, the "spirit," of the plant that is believed to have the therapeutic effect (18).
For a plant to have "power," certain rules have to be observed in collecting the plant. There is surprising agreement among the instructions reported from such geographically and culturally distinct tribes as the Iroquois of the Northeast and the Salishan of the Northwest (Vancouver Island). In both tribes, the importance of collecting plants in the morning is stressed, tree bark is to be taken from the eastern side of the tree, an offering of tobacco is to be made (
11,
18), and prayers need to be said (
16,
18). Such details regarding the collection procedure or, perhaps more important, the precise plant part used and the method of its preparation, are not always reported. This lack of information and the fact that medicinal use of plants by North America's indigenous residents commonly, if not always, transcended the mere physical contributes to the paucity of literature dealing with their medicinal properties.
Despite the availability of many of these botanicals in health food stores and, to an increasing extent, in supermarkets and pharmacies, scientific research regarding efficacy and safety is limited. Most medicinal botanicals have not been investigated to any great extent, and rarely has the focus of such research been specifically on medicinal botanicals used by Native Americans. Fortunately, however, some of the species used medicinally by Native Americans are also native to other parts of the world (eg, Sambucus nigra, Sambucus racemosa, and J. communis); others were introduced to European settlers by indigenous North American populations and have subsequently become popular in Europe [eg, Echinacea species (19) and Lobelia inflata (20)]. Intentionally or accidentally, settlers from other continents, in turn, brought some of their native botanicals, resulting in the eventual use of some foreign species by Native Americans (eg, Urtica dioica and Tanacetum vulgare). Thus, what little research exists on species used by original North American inhabitants predominantly comes from other countries where the same species were used, often for the same therapeutic purposes as those reported by Native Americans. However, even in plants grown within the same vicinity, differences in the amounts and ratios of chemical constituents, and thus of biological activity, will arise, depending on environmental conditions (21); the time of harvest, storage, and processing and the extraction procedure will introduce further variability (22, 23).
Answers to all your Biology Questions
