A first prospective, randomized, double-blind, placebo-controlled study on the use of a standardized hop extract to...

To examine the efficacy of a hop extract enriched in 8-prenylnaringenin (8-PN, the phytoestrogen in hops, Humulus lupulus L.) on relief of menopausal discomforts.

A prospective, randomized, double-blind, placebo-controlled study over 12 weeks with 67 menopausal women, who were administered a hop extract standardized on 8-PN (100 or 250 microg). The responses were determined by means of a modified Kupperman index (KI) and a patients' questionnaire.

All groups, including placebo, showed a significant reduction of the KI both after 6 weeks and after 12 weeks. The hop extract at 100 microg 8-PN was significantly superior to placebo after 6 weeks (P=0.023) but not after 12 weeks (P=0.086). No dose-response relationship could be established, as the higher dose (250 microg) was less active than the lower dose both after 6 weeks and after 12 weeks. Still, a trend for a more rapid decrease of KI was noticed for both active groups as compared to placebo. In particular, the decrease in hot flush score (isolated from the KI) was found significant for both treatment groups after 6 weeks (P<0.01) with respect to placebo. Results of the patients' questionnaire were consistent with those of the KI, with the most pronounced effects being observed for the 100-microg treatment.

Daily intake of a hop extract, standardized on 8-PN as a potent phytoestrogen, exerted favorable effects on vasomotor symptoms and other menopausal discomforts. Hop-derived prenylated flavonoids may provide an attractive addition to the alternative treatments available for relief of hot flushes and other menopausal discomforts.