Ginger (Zingiber officinalis) is a member of the Zingiberaceae family.  Botanically, ginger appears as a creeping perennial on a rhizome, which spreads underground.  In the first year, a green, reed-like stem about 60 cm high grows from the plant’s rhizome. The plant is characterized by narrow, lanceolate to linear-lanceolate leaves some 15 - 30 cm long, which die off every year. The flower grows directly from the rhizome & terminates as a long, curved spike with white or yellow flowers. The thick, tuberous rhizome is the part of the plant harvested for therapeutic application. Preparations are said to taste aromatic and moderately spicy. 
Although native to Southeast Asia, Ginger is now cultivated throughout the world; including the United States, India, China, West Indies, Mexico, Africa, Fiji, and Australia. Ginger has historically been used in Traditional Chinese Medicine and Ayurvedic Medicine - the traditional system of medicine in India. In India, it is often applied topically to relieve headaches, toothaches, and to improve circulation to the limbs; as well as to address nausea and other conditions of the gastrointestinal tract. 
In following with Traditional Chinese Medicine, dried ginger is used for cold conditions characterized by pallor, poor appetite and digestion, cold limbs, vomiting, diarrhea, pale tongue, or thin, watery or white sputum. [4, 5] Fresh ginger is used to promote sweating and to disperse the exterior cold caused by external influences upon the body; like pathogenic wind cold that results in upper respiratory tract infections.
Medicinal actions ascribed to ginger: [2, 6]
- general stimulant
- positive inotropic and chronotropic
- peripheral circulatory stimulant
- gastrointestinal stimulant
The main constituents in ginger are; volatile oils, accounting for approximately 1 - 3% (i.e. sesquiterpenes, zingiberene, beta-sesquiphellandrene and beta-bisabolene); as well as starch, proteins, proteases, vitamins, and resins.  The pungent or hot principles are attributed to the gingerols (1 - 2.5%) and shogaols.  Gingerols decompose into shogaols upon drying and storage. Shogaol has shown the ability to act as an analgesic in clinical study. Ginger extracts have also demonstrated antibiotic effects against Salmonella typhi, E. coli, Staph aureus, and Strep viridans.  Furthermore, aqueous extracts of ginger (as dilute as 2.5%) have demonstrated effectiveness against Trichomonas vaginalis. 
Anti-inflammatory properties of ginger are attributed to the inhibition of prostaglandin (COX-2), leukotriene (5-LOX), and thromboxane synthesis. [6, 10, 11] Inhibition of thromboxane synthesis and lipid peroxide formation is also purported to cause a reductions in platelet aggregation. Ginger also inhibits IL-1 and TNF (tumor necrosis factor).
Pharmacologic activity in the gastrointestinal tract includes ginger’s ability to impair cholesterol absorption, thereby reducing serum and hepatic cholesterol levels. Ginger is also thought to stimulate 7-alpha-hydroxylase; the rate limiting enzyme in bile acid synthesis.
Ginger remains a classic treatment for nausea and vomiting, as modern studies validate its use for these conditions. A systematic review of randomized clinical trials was published in 2000.  The authors summarized that ginger was found to be superior to placebo and equally effective as metoclopramide for post-operative nausea and vomiting in two of three studies. Other trials also demonstrated ginger’s efficacy in treating sea-sickness, morning sickness, and chemotherapy-induced nausea.
Because of its apparent effectiveness in these conditions, ginger is commonly recommended for pregnant women as a natural approach to thwart the nausea and vomiting associated with pregnancy. For years, practitioners wondered whether the therapy was effective and, most importantly, safe for the fetus. A randomized controlled equivalence clinical trial was conducted in Australia in 2004 to estimate whether the use of ginger to treat nausea or vomiting in pregnancy is equivalent to pyridoxine hydrochloride; also known as vitamin B6. 
291 women who were less than 16 weeks pregnant took 1.05 g of ginger or 75 mg of vitamin B6 daily for 3 weeks. The results showed that ginger was equivalent to vitamin B6 in reducing nausea, retching, and vomiting. A previous trial also found ginger to be effective in relieving the severity of nausea and vomiting associate with pregnancy (i.e. ‘morning sickness’).  This study highlighted 70 women whom were administered 1 gram daily for 4 days in a randomized double-blind study, conducted at or before 17 weeks’ gestation. The results showed that nausea and vomiting episodes decreased without any adverse effect on pregnancy outcome.
As mentioned, ginger has anti-inflammatory activity, thus it may be useful for treating inflammation of the joints, or as ii is most commonly termed, osteoarthritis. In a randomized double-blind, placebo-controlled, multi-center, parallel-group study, 261 patients with moderate-to-severe pain from osteoarthritis of the knee, were examined.  A highly purified and standardized ginger extract had a statistically significant, moderate effect on reducing knee pain symptoms when administered over a six week period. However, some mild adverse gastrointestinal effects were reported.
Another study involved 56 patients with various musculoskeletal disorders (i.e. rheumatoid arthritis, osteoarthritis, muscular discomfort). Patients using powdered ginger to relieve their symptoms over a period from 3 months to 2.5 years received benefit. All the patients with muscular discomfort experienced relief in pain, and over ¾ of patients with arthritis experienced relief in pain and swelling. Additionally, no adverse effects were experienced in this study. 
An interesting application for ginger is regarding it use in breech presentation. In a large placebo-controlled trial conducted upon pregnant women of 28 to 38 weeks gestation with breech position, fresh ginger paste or placebo was applied to the Zhihying acupoint.  Ginger was effective in correcting the fetal position in 77.4% of cases (113 women), versus a 51.6% correction rate in the control group.
Other cases for which ginger may be beneficial include; addressing migraine headaches, improving gastroduodenal motility, inhibiting serotonin-induced diarrhea, treatment of peptic ulcers, and reducing platelet aggregation. [18, 19]
Dosages are dependent on the type of preparation. Fresh root can be taken as the equivalent of 500 - 1000 milligrams, three times daily. Dried root doses are commonly administered in the 500 mg dosage range, two to four times daily. Ginger tablets are available in 500 mg capsules and may be taken as a dose of one capsule, two to four times per day. Liquid extracts of 1:2 strength dosages range from 0.7 - 2.0 milliliters daily; while 1:5 dilutions range anywhere from 1.7 - 5.0 ml per day. 
Ginger is not recommended in persons with sensitive stomachs, as they do not always tolerate this plant well. It remains contraindicated for persons with gallstones (without physician supervision in the case of larger stones and acute symptoms) and pregnancy (specifically larger doses, greater than 2 gram doses).  In pregnancy, large doses may inhibit thromboxane synthetase, impairing development of the male fetal brain. Caution is also advised in patients with inflammatory skin diseases, high fever, bleeding conditions, or ulcers. 
Ginger may interact with a number of prescription medications.  Co-administration of ginger and anticoagulant medications like warfarin can be problematic. Ten grams at one dose has been shown to extend bleeding time and decrease platelet aggregation, while 4 gram doses or less generally do not interfere.
Another study with a 1 gram dose immediately prior to surgery to prevent post-operative nausea has not affected bleeding indices. Ginger can increase the absorption of oral drugs, thereby having far reaching effects. On the other hand, ginger can decrease vomiting caused by cyclophosphamide - chemotherapeutic agents. Interestingly, the administration of a 1.0 gram powdered ginger supplement 20 minutes prior to surgery reduced anesthetic induced nausea.
Adverse effects of ginger use may include contact dermatitis with topical applications in ginger-sensitive patients.  There does not appear to be any toxic actions associated with ginger, though large doses may cause gastrointestinal upset with dyspepsia and retrosternal burning in some individuals.
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