8-Prenylnaringenin is the most estrogenic phytoestrogen known. Its effects are similar to, but weaker than estradiol. 8-Prenylnaringenin is found in hops (Humulus lupulus). It can be produced from isoxanthohumol in fungal cells cultures, and by flora in the human intestine. 8-Prenylnaringenin has been demonstrated to reduce hot flashes. 8-Prenylnaringenin also influences prolactin, and increases other estrogenic responses. 8-prenylnaringenin binds to and activates ER-α more times than it does to ER-β. This prenylflavonoid also interacts with the progesterone receptor. This prenylflavanoid has drawn interest in the study of hormone replacement therapy, and it is comparable to selective estrogen-receptor modulators. In an in vivo study, 8-prenylnaringenin has activated proliferation of mammary cells. At the concentration found in beer, it is unlikely to have an estrogenic effect in breast tissue.