Zingiber officinale (ginger) as an anti-emetic in cancer chemotherapy: a review

Despite significant advances and development of novel anti-emetics, nausea and vomiting (emesis) is a major side-effect of cancer chemotherapy. At times, severe nausea and vomiting may also lead to reduction in adherence to the treatment regimen, and this will concomitantly affect the patient's survival. The rhizome of Zingiber officinale, commonly known as ginger, is globally an important spice. It has been used for centuries in the Indian, Chinese, Arabic, Tibetan, Unani, and Siddha systems of traditional medicine to treat nausea and vomiting induced by different stimuli. Preclinical studies with experimental animals (dogs and rats) have shown that the various extracts of ginger and the ginger juice possess anti-emetic effects against chemotherapy-induced nausea and vomiting. Gingerol, the active principle, is also shown to possess anti-emetic effects in minks. However, with regard to humans, while most studies have been supportive of the preclinical observations, a few have been contradictory. The exact mechanism responsible for the anti-emetic effects of ginger is unknown; however, the ginger phytochemicals, especially 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol, may function as a 5-hydroxytryptamine (5-HT3) antagonist, NK1 antagonist, antihistaminic, and possess prokinetic effects. The present review for the first time attempts to address the anti-emetic observations and the variability in response of the anti-emetic effects of ginger in cancer chemotherapy. An attempt is also made to address the lacunae in the published studies and emphasize aspects that need further investigations for ginger to be of use in clinics as an anti-emetic agent in the future.