Variation in concentration and labeling of ginger root dietary supplements.

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.