Ginger is an herb. The rhizome (underground stem) is used as a spice and also as a
medicine. It can be used fresh, dried and powdered, or as a
juice or
oil.
Ginger is commonly used to treat various types of "stomach problems," including motion sickness, morning sickness,
colic, upset stomach, gas, diarrhea,
nausea and vomiting after surgery, as well as loss of appetite. Other uses include treating upper respiratory tract
infections,
cough, and bronchitis.
Schwertner HA, Rios DC, Pascoe JE.
Variation in concentration and labeling of ginger root dietary supplements. 1. Obstet Gynecol. 2006 Jun;107(6):1337-43. 
OBJECTIVE:
ginger root dietary
supplements are often used to alleviate symptoms of
nausea and vomiting associated with
pregnancy. In this study, we determined the variation in 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol concentrations and labeling of different brands of
ginger root dietary
supplements. METHODS: Ten different
ginger root dietary
supplements were purchased randomly at local pharmacies and
health food stores. The 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol concentrations of the dietary
supplements were determined by high-performance liquid-chromatography. In addition, we examined the container labeling for the amount of
ginger root powder or extract in each capsule, the serving size, ingredients, expiration date, lot number, standardization procedure, and suggested use. RESULTS: The 6-gingerol
concentration of the
ginger powder dietary
supplements ranged from 0.0 to 9.43 mg/g, (mean +/- standard deviation, 2.56 +/- 2.95 mg/g), 6-shogaol ranged from 0.16 to 2.18 mg/g (1.27 +/- 0.58), 8-gingerol ranged from 0.00 to 1.1 mg/g (0.47 +/- 0.34), and 10-gingerol ranged from 0.00 to 1.40 mg/g (0.36 +/- 0.51). The amounts of 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol in the
ginger root dietary
supplements varied widely on both a milligram per gram basis and on a milligram per capsule basis. Likewise, the suggested
ginger serving sizes varied from 250 mg to 4.77 g per day. CONCLUSION: The results of this study indicate that there is a wide variation in the gingerol composition and in the suggested serving sizes of
ginger root powder from different manufacturers. LEVEL OF EVIDENCE: II-3.