The genus Humulus includes three species of slender twining vines native to temperate regions of the Northern Hemisphere. Hops is widely distributed in Europe, Asia, and North America. Male and female flowers are found on separate plants; the numerous, tiny wind-pollinated flowers are borne in a ?cone,? with each flower subtended by glandular scales. European cultivars of hops have been widely used since medieval times to give beer flavor and aroma and to improve its stability; the small yellow glands on hops contain compounds that provide bitter flavor and antibacterial activity. Native American varieties of wild hops are not commercially cultivated, but may have contributed to the ancestry of some American cultivated hops. A second wild American species does not have equivalent chemical content and could not be used interchangeably. Hops infusions or tinctures have long been used medicinally for a sedative or soporific effect, both in Europe and in North America, and infusions used topically for inflammation and injuries. Hops also are a popular ingredient in herbal pillows.

Research into the medicinal use of hops has been limited. Several small human studies have supported the sedative effect of hops in combination with other botanicals used for the same purpose, especially valerian. Animal studies find sleep-enhancing and antidepressant properties in single-plant hops extracts; at least three classes of active compounds contribute to these activities. Certain compounds in hops and their metabolites have phytoestrogenic activity, and one small human trial has shown that a hops extract reduced menopausal symptoms. More research is needed. Several compounds in hops have cancer-preventive activity in lab studies.

Selected References

Gerhauser, C. 2005. Beer constituents as potential cancer chemopreventive agents. Eur. J. Cancer 41:1941-1954.

Hampton, R., G. Nickerson, P. Whitney, and A. Haunold. 2002. Comparative chemical attributes of native North American hop, Humulus lupulus var. lupuloides E. Small. Phytochemistry 61:855-862.

Heyerick, A., S. Vervarcke, H. Depypere, M. Bracke, and D. de Keukeleire. 2006. A first prospective, randomized, double-blind, placebo-controlled study on the use of a standardized hop extract to alleviate menopausal discomforts. Maturitas 54:164-175.

Orth-Wagner, S., W. J. Ressin, and I. Friedrich. 1995. Phytosedativum gegen Schlafstörungen. Klinische Wirksamkeit und Verträglichkeit eines Phytosedativums mit Auszügen aus Baldrianwurzel, Hopfenzapfen, und Melissenblättern. Z. Phytother. 16:147-156.

Schiller, H., A. Forster, C. Vonhoff, M. Hegger, A. Biller, and H. Winterhoff. 2006. Sedating effects of Humulus lupulus L. extracts. Phytomedicine 13:535-541.

Small, E. 1979. A numerical and nomenclatural analysis of morphogeographic taxa of Humulus. Syst. Bot. 3:37-76.

Small, E. 1997. Cannabaceae. Pp. 381-387 in: Flora of North America Editorial Committee, eds. Flora of North America, vol. 3. Oxford University Press, New York.

Zanoli, P., M. Rivasi, M. Zavatti, F. Brusiani, and M. Baraldi. 2005. New insight in the neuropharmacological activity of Humulus lupulus L. J. Ethnopharmacol. 102:102-106.