The genus Glycyrrhiza includes 18 species that range from Eurasia to Australia and the Americas; most have medicinal uses. Glycyrrhiza glabra is native to Europe and western Asia and is widely cultivated. It is a large perennial herb with pinnately compound leaves and racemes of bilabiate, pale violet flowers. The parts used medicinally and for flavoring are the long taproots and the creeping rhizomes or stolons present in one subspecies, which have a characteristic sweet taste. Licorice is used in many cultures for coughs and sore throats, to treat and prevent ulcers, and for liver disease. It is also used to flavor foods and beverages and to make licorice candies (although some candies called ?licorice? today contain little or no actual licorice).

Numerous bioactive compounds have been identified in licorice; one of the most abundant and best-studied of these is glycyrrhizin. Most evidence from human clinical trials in older literature indicates that licorice can alleviate gastritis and ulcers, possibly as well as Western pharmaceutical treatments of the time (however, in modern practice, most ulcers are treated with antibiotics, as they are now known to be caused by bacteria). Some studies that used deglycyrrhizinated preparations, which remove glycyrrhizin to reduce the possibility of side effects, did not show any benefit, although others did. A more recent clinical trial of a multiherb formula for dyspepsia that included licorice showed highly positive results. Licorice has a liver-protective effect in vitro, and human studies of Asian multiherb formulas including licorice have shown benefit for hepatitis and cirrhosis. However, one German authority suggests that licorice should be avoided by people with cirrhosis and cholestatic liver disorders. Multiple human clinical trials have demonstrated that glycyrrhizin, given intravenously as an isolated compound, can reduce elevated liver enzymes and reduce the risk of liver cancer in patients with active chronic hepatitis C; it has been used for this purpose in Japan for decades. Glycyrrhizin can deplete potassium in the body, so consumption of large doses of licorice over long periods of time can cause edema, elevated blood pressure, and cardiovascular symptoms. This condition has been reported in people who eat excessive amounts of licorice hard candies.

Selected References

Ikeda, K., Y. Arase, M. Kobayashi, et al. 2006. A long-term glycyrrhizin injection therapy reduces hepatocellular carcinogenesis rate in patients with interferon-resistant active chronic hepatitis C: a cohort study of 1249 patients. Dig. Dis. Sci. 51:603-609.

Kumada, H. 2002. Long-term treatment of chronic hepatitis C with glycyrrhizin [stronger neo-minophagen C (SNMC)] for preventing liver cirrhosis and hepatocellular carcinoma. Oncology 62 Suppl. 1:94-100.

Madisch, A., G. Holtmann, G. Mayr, B. Vinson, and J. Hotz. 2004. Treatment of functional dyspepsia with a herbal preparation. A double-blind, randomized, placebo-controlled, multicenter trial. Digestion 69:45-52.

Orlent, H., B. E. Hansen, M. Willems, et al. 2006. Biochemical and histological effects of 26 weeks of glycyrrhizin treatment in chronic hepatitis C: a randomized phase II trial. J. Hepatol. 45:539-546.

Stormer, F. C., R. Reistad, and J. Alexander. 1993. Glycyrrhizic acid in liquorice ? evaluation of health hazard. Food Chem. Toxicol. 31:303-312.

van Rossum, T. G., A. G. Vulto, R. A. de Man, J. T. Brouwer, and S. W. Schalm. 1998. Review article: glycyrrhizin as a potential treatment for chronic hepatitis C. Aliment. Pharmacol. Ther. 12:199-205.

Yeo, P. F. 1968. Glycyrrhiza. P. 127 in: T. G. Tutin et al., eds. Flora Europaea, vol. 2. Cambridge University Press: Cambridge.