Not all ginger is created equally. . .

. . . which may explain why results of studies to determine whether ginger relieves nausea and vomiting have been inconsistent.

Researchers recently found that supplements containing ginger root powder vary widely in their composition of 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol, the principal components of ginger powder. They looked at 10 random ginger root supplements from local pharmacies and health food stores and found variations to occur both on a mg-per-gram basis and on a mg-per-capsule basis. Concentrations of the four elements varied 8.1-, 15.6-, 2.8-, and 3.9-fold, respectively. One brand contained no 6-gingerol, 8-gingerol, or 10-gingerol at all. Similarly, the suggested serving size varied from 250 mg to 4.77 g per day.

The researchers concluded that clearly more research is needed to determine the appropriate dose, the lower limits of effectiveness, and the safety, bioavailability, and pharmacokinetics of these ginger components.

Commentary from Sharon Phelan MD, FACOG, Professor Ob/Gyn, University of New Mexico Health Science Center School of Medicine Albuquerque, NM:

The use of ginger for the nausea and vomiting of pregnancy has been popular for decades and has a number of studies that support its benefits.

This article emphasizes the lack of consistency in the product used. Anytime one uses a botanical derivative such as ginger, many factors that are not controlled can impact the potency and hence effectiveness of a given preparation. The temperature, humidity, and soil conditions when grown, where in the world the item was grown, and the processing of the botanical will all play a huge part in the final potency. These cannot even be controlled by a given manufacturer let alone across brands. As the research shows, without knowing the key ingredient that is providing the medical benefit it's impossible to standardize botanical preparations. The take-home message is if one ginger preparation does not work, another might-or might not. Patients need to appreciate this lack of true standardization is an integral part of complementary alternative medicine.