Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer.

The female flowers of the hop plant are used as a preservative and as a fla voring agent in beer. However, a recurring suggestion has been that hops ha ve a powerful estrogenic activity and that beer may also be estrogenic. In this study, sensitive and specific in vitro bioassays for estrogens were us ed for an activity-guided fractionation of hops via selective solvent extra ction and appropriate HPLC separation. We have identified a potent phytoest rogen in hops, 8-prenylnaringenin, which has an activity greater than other established plant estrogens. The estrogenic activity of this compound was reflected in its relative binding affinity to estrogen receptors from rat u teri. The presence of 8-prenylnaringenin in hops may provide an explanation for the accounts of menstrual disturbances in female hop workers. This phy toestrogen can also be detected in beer, but the levels are low and should not pose any cause for concern.