Nature's Pharmacopeia: A World of Medicinal Plants
Originating in South Asia and now cultivated throughout the tropics, ginger has long been valued in Asian cuisine and medicine and now also in Africa, the Caribbean, and elsewhere. The perennial plant reaches a height of about 1.5 meters, with numerous narrow, dark-green, sword-shaped leaves emerging alternately from leaf bases that sheath the stem and shorter inflorescence stems in the form of a spike of tubular orange and purple flowers.216 The underground portion (gingerroot) is largely a branching rhizome of variable size that gives rise to both roots and stems. The rhizome is harvested for its sweet, pungent spiciness and aroma, considered to be flavorful and healthy (figure 14.29).
FIGURE 14.29 Ginger for sale at a street market in Hong Kong.
The ancient Indian Sanskrit texts uphold ginger, endowed with special purifying properties, as “the great cure” and “the great medicine.”217 From its South Asian origin, ginger spread along the routes of commerce and took its place in East Asian and Mediterranean medicine.218
The Chinese employed ginger as a medicinal ingredient at least 2000 years ago, when ginger-root appeared in an early materia medica.219 Classified as a hot herb, ginger has the capacity to promote yang in the body and disperse cold qi, according to traditional medical thought. In the Chinese pharmacological framework, it is often mixed with other herbs to modulate its effects and is used to treat abdominal pain and vomiting, cough, and some types of bleeding, among many other ailments.220
Ginger reached the Mediterranean region in antiquity, when traders operating between the Indian subcontinent and the Near East supplied the spice market with exotic products such as pepper (Piper nigrum) and cardamom (Elettaria cardamomum). While the Greek herbalist Dioscorides did not quite know where ginger came from—he wrote that it grew in “Troglodytic Arabia”—he recommended it for its “warming and digestive properties.” As he advised, “It gently softens the bowel and it is wholesome.”221
Later European authorities elaborated on ginger’s qualities, writers such as Gerard, whose herbal described dried gingerroot as hot and dry, in the humoral framework of medicine, but fresh or pickled ginger as hot and moist, with the particular attribute of “provoking venerie” as an aphrodisiac.222 A French pharmaceutical encyclopedia of the late seventeenth century recorded that gingerroot was rarely used, except in powdered form as a flavoring called white spice. Northern Europeans, such as the Dutch and English, according to this source, consumed candied ginger or ginger marmalade from time to time as a warming agent, to improve digestion, and to prevent scurvy when at sea.223 Ginger-containing beverages and syrups have persisted in the medical-culinary marketplace in recent centuries (figure 14.30).
FIGURE 14.30 An advertising poster for an elixir that contained ginger, ca. 1860. (Library of Congress, Prints and Photographs Division, LC-USZC2-291)
Gingerroot contains a complex assortment of chemical compounds that might act singly or in combination to produce its flavors and diverse medicinal attributes. Among the many chemicals extractable from the rhizome are an oleoresin (4–7.5 percent), composed of pungent chemicals (for example, phenolic compounds such gingerols and shogaols that accumulate on drying) and terpenoid volatile oils (1–3.3 percent).224 Much of the current ginger research aims to test its capacity to reduce nausea and vomiting, such as accompanies gastrointestinal troubles, pregnancy, certain drug treatments, and motion sickness.225 The mixture of ginger compounds being so flavorful and biting, it is a challenge to design proper placebo controls in such trials. Potential technical limitations aside, clinical evidence is gathering that ginger probably does reduce nausea and vomiting in diverse therapeutic settings.226
Gingerroot has also been suggested as an anti-inflammatory or analgesic herb, and clinical evidence for this application remains mixed.227 With continued improvements in experimental design and a better understanding of potential biochemical mechanisms of action, ginger’s ancient roles in health and cuisine may be extended in a new era of biomedical practice.