Ginger (Zingiber officinale) is a perennial typically growing two to four feet in height and preferring warm, humid climates. It has narrow, glossy, bright green leaves, and its summer flowers (rarely seen) are yellowish green. The rhizome is the part used for culinary and medicinal purposes. Commercial varieties of ginger are usually described in relation to their geographic origin. Commonly found in Southeast Asia, India, Africa, and the West Indies, this herb can be cultivated in other areas with proper growing conditions.
Ginger has a long history of medicinal use. It is one of the best-known medicinal herbs in China and Japan, where it has commonly been prescribed for headaches, nausea and other stomach problems, and colds. Characterized as "spicy" and "hot," ginger is claimed to "warm the body and treat cold extremities, improve weak and tardy pulses, address pale complexions, and strengthen the body after blood loss."
In India, ginger in both fresh and dry powdered forms is used in cooking and in Ayurvedic medical practice. Classified by Ayurvedic practitioners as pungent with a sweet aftertaste, ginger's virya, or potency, is "hot." Ginger is reputed to balance the doshas (the three organizing principles providing for homeostasis in Ayurvedic medicine), address symptoms of colds and other viral infections, enhance digestion, stimulate appetite, and lessen arthritis. In some African countries, for example Nigeria, ginger has been used to treat malaria and yellow fever. In the West Indies it has been given for urinarytract infections.
In Western alternative medicine practice, the primary uses of ginger include prevention of motion sickness, prevention of nausea, and treatment of rheumatologic conditions as an anti-inflammatory.[6,7] In vitro evidence suggests that ginger may have anticancer effects.
The mechanism underlying ginger's purported antiemetic activity is unknown, but there is speculation of a direct effect on the gastrointestinal tract. A mechanism involving the central nervous system cannot be ruled out, since several of ginger's components antagonize serotonin type 3 receptors, but this has not been clearly demonstrated.[9,10,11] In vitro studies suggest that ginger may produce its anti-inflammatory effect by inhibiting arachidonic acid metabolism in both the cyclooxygenase and lipoxygenase pathways.[12,13]
The active constituents of ginger are not known with certainty, but studies of the lipophilic rhizome extracts have yielded the potentially active constituents gingerols and shogaols. Most investigators have concluded that ginger increases gastrointestinal motility.[10,15,16] Aqueous extracts of the fresh rhizome inhibited platelet aggregation in vitro in a dose-dependent fashion. The extract significantly reduced formation of thromboxane B 2 and platelet prostaglandin endoperoxides. However, daily consumption of 15 g of raw ginger rhizome or 40 g of cooked rhizome by 18 healthy volunteers for two weeks failed to decrease platelet cyclooxygenase activity. Clinically, differences in bleeding time, platelet count, and platelet functioning compared with placebo were not found in eight healthy volunteers given a single 2-g dose of the dried rhizome.
The first clinical study of ginger in Western literature was performed by Mowrey and Clayson  in 1982. Powdered ginger rhizome 940 mg was compared with oral dimenhydrinate 100 mg and with placebo in 36 male and female undergraduates who reported a high susceptibility to motion sickness. Ginger was superior to dimenhydrinate and placebo for the prevention of motion sickness when administered 20-25 minutes before testing in a motor-driven rotating chair.
Ginger's efficacy against motion sickness was tested in a more realistic setting in a double-blind, randomized study involving 80 healthy naval cadets who were unaccustomed to sailing in heavy seas. The cadets took either 1 g of powdered ginger rhizome or 1 g of placebo while sailing in heavy seas and maintained scorecards noting their symptoms every hour for the next four hours. For the 48 sailors who reported symptoms of seasickness, ginger appeared to reduce the severity of seasickness (measured as a score of 0-9) rather than reducing the number of subjects who reported symptoms. Not all studies of ginger for motion sickness have reported positive findings, however. Ginger did not affect gastric emptying in patients tested in a rotating chair.
Ginger has also been studied for its effects as a postoperative antiemetic in women undergoing same-day laparoscopic gynecologic surgery.[21,22,23,24] Two of the studies randomized a total of 180 women to treatment with ginger, metoclopramide, or placebo.[21,22] Both studies concluded that powdered ginger rhizome in single doses of 500-1000 mg was similar to oral metoclopramide 10 mg in decreasing the frequency of nausea and vomiting after surgery, and both were more efficacious than placebo (p < 0.05). These results contrast with those of another randomized study in which 120 women were given powdered ginger rhizome 2 g with or without droperidol 1.25 mg, droperidol alone, or placebo one hour before induction of anesthesia. Although postoperative vomiting was less prevalent in the three treatment groups than in the placebo group, the differences were not statistically different. A fourth trial, in 108 women, found nonsignificant, dose-related differences in the rate of nausea and vomiting between those who took powdered ginger rhizome 500-1000 mg one hour before surgery and those given placebo.
Twenty-seven pregnant women with hyperemesis gravidarum before week 20 of pregnancy were randomized to either ginger (250 mg of powdered root in capsules) or placebo (lactose) four times daily for four days in a double-blind, crossover trial. Improvement in nausea, vomiting, and weight loss was greater when the women received ginger than when they received placebo (p = 0.035).
Although ginger has been used historically to treat rheumatic disorders, and although ginger extracts have shown the ability to inhibit arachidonic acid metabolism -- potentially providing an anti-inflammatory action -- very limited efficacy data supporting this indication have been published. A retrospective case series reported on the use of various dosages and dosage forms (fresh versus powdered ginger) in 28 patients with rheumatoid arthritis, 18 of them with osteoarthritis and the rest with muscular discomfort. The patients subjectively described symptom relief, with many reporting that they were able to reduce their use of other antiarthritic drugs.
The typical dose of ginger for the prevention of nausea and vomiting ranges from 500 to 1000 mg of powdered dry rhizome, which is equivalent to 2 to 4 g of fresh or candied rhizome (about 1 inch of the substance), and is consumed one hour before exposure.[6,7,26] The dosage reported for treatment of rheumatoid arthritis or osteoarthritis is 500-1000 mg of powdered rhizome daily.
Adverse effects have not been reported for ginger in humans. In animal studies to determine acute toxicity, 2.5 g/kg/day for seven days did not cause adverse effects, but 3-3.5 g/kg/day killed 10-30% of the animals. Clinically relevant platelet-inhibiting effects were not apparent after healthy volunteers received single 2-g doses of dried ginger rhizome.
No drug interactions involving ginger have been reported.
Ginger is a menstrual stimulant and potential abortifacient when taken in dosages greater than 250 mg four times daily.[25,27] In the study of ginger for the treatment of hyperemesis gravidarum, of the 25 women who went to full-term, all babies were born at a mean gestational age of 39.9 weeks and had Apgar scores of 9 or 10 (10 is the best possible score) at five minutes. One woman had a spontaneous abortion during week 12. Infants were not followed by the researchers beyond birth.
Although ginger has a long history of medicinal use, clinical studies supporting its value for the treatment of rheumatoid arthritis are lacking. There is some evidence supporting a role in the prevention of nausea and vomiting, but much more research is needed. Ginger appears to be relatively safe except in pregnancy.
Am J Health Syst Pharm. 2000;57(10) © 2000 American Society of Health-System Pharmacists
Cite this: Alternative Therapies: Ginger - Medscape - May 15, 2000.