Ginger is a popular herb used for both culinary and medicinal purposes. Though frequently referred to as a root, ginger is technically a rhizome of the plant Zingiber officinale. From its origins in southern China, ginger is now cultivated all over the tropical and subtropical regions of Asia and South America, as well as on the Caribbean island of Jamaica.1 It has a lemonlike aroma and a warm, pungent taste, and it is a popular ingredient in cuisines all over the world.

Background

Though the flower and leaf of the ginger plant are ornamental and attractive, the root/rhizome structure is the source of the aromatic spice. Ginger root can be found in all forms from fresh to candied, dried, and pickled. Further processing produces powdered ginger, available in loose and capsule form. Many shelf-stock seasonings and cooking sauces contain ginger.

Ginger owes its unique taste to the nonvolatile phenylpropanoids (mainly gingerol and zingerone) and diarylheptanoids (gingeroles and shoagoles). These compounds compose the essential oil of ginger that constitutes up to 3% of the root. Freshly harvested young ginger root is juicy and fleshy, with a mild taste. Older rhizomes become dry and very fibrous.2

Medicinal uses

Ginger has been widely used for centuries to treat mild stomach upset, nausea, and dyspepsia. Documented in ancient Chinese lore as long ago as 4,000 years, few herbs have been so plentiful and widely used.3 More recently, some formal studies have shown definite antiemetic effects in motion sickness, postoperative nausea and vomiting, and nausea and vomiting of early pregnancy. Ginger has been on the FDA’s Generally Regarded As Safe list for years, making it an attractive herbal recommendation.4

In a double-blind study involving placebo, ginger, and dimenhydrinate, a motion simulator was used to induce motion sickness. The participants who ingested ginger root (approximately 1 g) prior to the study were able to tolerate the motion for several minutes longer without any nausea or vomiting than the placebo or dimenhydrinate participants.5 Though this trial involved only 36 subjects, the results were impressive.

Two trials documented ginger’s utility in postoperative nausea and vomiting. Both were active and placebo-controlled trials involving major abdominal surgeries.5 Though participant numbers were small (fewer than 300 total), results were consistent for ginger’s being at least as effective as the active control, and without any of the central nervous system (CNS) anticholinergic side effects of traditional antiemetics.5 In two interesting trials, a 1-g preoperative dose of ginger even reduced the need for postoperative nausea and vomiting management.3

The American College of Obstetricians and Gynecologists has issued a statement citing ginger as possibly useful for uncomplicated nausea and vomiting of early pregnancy.6 It has been shown safe and superior to placebo. The American Herbal Products Association (AHPA) recommends that fresh ginger be used (rather than dried or processed) to maximize safety. Use should also be limited to 1 g/day for no longer than four days. This recommendation was given a class 1 safety rating by the AHPA.4Another aspect of ginger’s appeal is its pleasant taste, as well as its ready availability. Ginger ale, ginger sauce, ginger capsules, and ginger sticks can be found in most large grocery stores and are palatable for all ages.

Mechanism of action

Similar to many other herbals, ginger’s mechanisms of action are not fully understood. However, most studies agree that the GI-protective effect seems to be due to an increase in mucosal defenses and potentiation of natural protective effects, similar to metoclopramide. Ginger is also a saliva-inducing agent.5

How supplied, dosage

Although ginger is available in practically every conceivable form, the forms most commonly recommended are powdered and fresh root. Typical recommended doses for any etiology of nausea and vomiting are 500-1,000 mg of powdered root or 1,000 mg of fresh root in divided doses daily.5

Safety, drug interactions, and allergies

Several known possible drug interactions are associated with ginger. The potential for both enhancement and retardation of prescription drugs used concomitantly with ginger exists. Increased bleeding time is possible when ginger is used by patients taking oral anticoagulants.4

Ginger allergies are not common, but they do exist. These have usually been reported as GI gaseous activity but can also involve respiratory distress and angioedema.4 Allergic contact rashes have been reported. These may be more likely in individuals who work regularly with ginger, apply ginger to the skin, or have a positive allergy test for balsam of Peru. An allergic eye reaction has also been reported.7

Summary

Current pharmacotherapies for nausea and vomiting come with significant side-effect profiles. Phenothiazines can have serious CNS effects, including extrapyramidal dystonia. Anticholinergics are contraindicated in some conditions and come with drying, sedative, and other CNS effects. The newer antiemetics for chemotherapy nausea and vomiting are very costly. Safety has always been a challenge for any drug recommended in early pregnancy. Consequently, the ability to add ordinary grocery-store-variety ginger root to our arsenal for morning sickness, motion sickness, and postoperative nausea and vomiting is a welcome bonus. Considering that the safety requirements for therapies in early pregnancy are among the most stringent in medicine, ginger’s safety rating could hardly be better.

References

1. Gernot Katzer’s Spice Pages. Ginger. Available at www.uni-graz.at/~katzer/engl/Zing_off.html. Accessed March 15, 2007.

2. Wikipedia. Ginger. Available at http://en.wikipedia.org/wiki/Ginger. Accessed March 15, 2007.

3. University of Maryland Medical Center. Ginger. Available at www.umm.edu/altmed/ConsHerbs/Gingerch.html. Accessed March 15, 2007.

4. Skidmore-Roth L. Mosby’s Handbook of Herbs & Natural Supplements. 3rd ed. St. Louis, Mo.: Elsevier Mosby; 2006:482.

5. Fetrow CW, Avila JR. Professional’s Handbook of Complementary & Alternative Medicines. Springhouse, Pa.: Springhouse Corp; 1999:275.

6. American College of Obstetricians and Gynecologists. ACOG Issues Guidance on Treatment of Morning Sickness During Pregnancy. Available at www.acog.org/from_home/publications/press_releases/nr03-29-04-1.cfm. Accessed March 15, 2007.

7. Mayo Clinic. Ginger. Available at www.mayoclinic.com/health/ginger/NS_patient-ginger. Accessed March 15, 2007.