Ginger (Zingiber officinale Roscoe)
Ginger is a member of the Zingiberaceae Family and has been used for medicinal purposes since 100 AD. It was not until the 13th century that it was introduced to the kitchen as a taste sensation. Ginger is cultivated in many tropical regions, and different forms of processing result in different grades and qualities of the end product. Jamaican ginger is considered the best quality and Japanese ginger is of inferior quality to all the others. In Europe only scraped or unscraped, unbleached ginger is acceptable as a medicinal product.
Therapeutic Description: Ginger is claimed to relieve various forms of gastrointestinal distress such as motion sickness, seasickness, morning sickness in pregnancy, postoperative nausea, and flatulence.
Mechanism of Action: Ginger is composed of: 3% - 6% fatty oil, 9% protein, 60% - 70% carbohydrates, 3% - 8% raw fiber, 8% ash, 12% water, and 2% - 3% volatile oil. The volatile oil consists mainly of mono- and sesquiterpenes and Oleoresin (extraction residue). 4% - 7.5% of pungent substances in the volatile oil include gingerols, shogaol, zingerone, paradol and ziniberol (Lagner, et al. 1998). Studies by Holtmann, Clarke, Scherer, & Hohn (1989) and Phillips, Ruggier, & Hutchinson (1993) indicate that ginger acts directly on the gastrointestinal mucosa and not on the central nervous system, as was first thought. The efficacy of ginger appears to depend on aromatic, carminative and absorbent properties of the pungent substances. Yamahara, Rong, Iwamoto, Kobayashi, Matsuda and Fujimura (1989) reported acetone extract of ginger and gingerols exhibited an anti-serotonin effect, thereby inhibiting intestinal contractions and Huang, Iwamoto, et al. (1991) indicated these components selectively antagonize 5-HT3 receptors.
So, you have a site specific effect of gingerols as anti-spasmodics and more recent literature (not cited here) indicates that gingerols are potent anti-inflammatory agents, blocking prostaglandins and prostacylin production in inflammed tissues.
Evidence of Therapeutic Effects: Several studies indicated the effectiveness of ginger. Ginger was superior to standard anti-nausea drugs in reducing gastrointestinal symptoms of motion sickness. Vertigo symptoms were reduced more with ginger than a placebo in a double-blind crossover trial using induced motion sickness. In a double-blind, randomized, placebo-controlled trial on sea-sickness, ginger significantly reduced tendency to vomit and cold sweats better than a placebo. Powdered ginger root does not appear to effect nystagmus response (eye reaction) to vestibular or optokenetic stimulus and therefore indicates ginger has no effect on the CNS. In a double-blind, randomized, crossover study, ginger demonstrated significantly greater relief of morning sickness compared to a placebo.
Two randomized, double-blind studies showed both ginger and metoclopramide to have a similar effectiveness on postoperative nausea and vomiting, greater than the placebo. After ingesting ginger, patients who were treated with psoralens (which cause nausea), experienced a reduction of nausea.
--->Ginger does not affect the gastric emptying rate (Phillips, et al. 1993). It was found that in lab animals, gingerols have analgesic, sedative, antipyretic, antibacterial. and
GI motility effects, (O'Hara, Kiefer, Farrell, & Kemper, 1998).
Dosage and Regimens: Ginger root needs to be encapsulated to prevent oral and oesophageal irritation. The usual recommended adult dose of ginger root powder is between 250mg to 1g several times per day for symptoms of gastrointestinal distress.
Adverse Effects and Contraindications: Ginger inhibits platelet aggregation and thromboxane synthetase and excessive doses may interfere with existing cardiac, antidiabetic or anticoagulation therapy (Warfarin). However, evidence of ginger inhibiting platelet aggregation is found only when using large amounts of raw ginger and indicates it could be dose-related. During pregnancy and lactation, doses exceeding the amounts used in normal cooking should be avoided.
Ginger does not produce the undesirable side effects associated with other antiemetic (anti-vomiting) medications. No indication of side effects have been reported except for some degree of a heartburn sensation and rare cases of allergic reaction. [6]-gingerol is a potent mutagen, however, ginger juice also contains antimutogenic components that suppress [6]-gingerol (this suggests that use of the whole root is preferrable to an extract).
Discussion: Ginger has been repeatedly proven effective in subduing and alleviating many forms of gastrointestinal distress and is indicated as safe to use in moderate amounts. Overall, studies have proved it to have some effect on motion sickness and post-operative nausea. However, the studies fail to indicate any CNS involvement. Further investigation of ginger, as an antiemetic is required.
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