Hops May Improve Hot Flashes

Hops, prized in brewing since antiquity, may have a new use: relief of menopausal symptoms, according to Maturitas: The European Menopause Journal (2005 Nov 28; In press). In a new study, postmenopausal women who took a standardized extract of hops (Humulus lupulus) had improved quality of life and significantly fewer hot flashes.

The strobiles (leafy, cone-like catkins) of hops, like soy and red clover, contain hormone-like substances called phytoestrogens. The main phytoestrogen in hops is 8-prenylnaringenin (8-PN), which was standardized to two different strengths for this study. Phytoestrogens can interact with the body’s estrogen receptors and exert therapeutic effects, often in a more gentle manner than prescription hormone replacement drugs.

Sixty-seven postmenopausal women were randomly assigned to one of three groups for the 12-week, double-blind study: group 1 took 120 mg per day of hops extract (providing 100 mcg of 8-PN); group 2 took 300 mg of hops extract per day (providing 250 mcg of 8-PN); group 3 took a placebo.

Women who took the hops extracts had fewer menopause-related complaints; however, the women taking placebo also improved significantly overall. The women in both hops groups had fairly rapid improvement of hot flashes for 6 weeks, while the placebo group was affected to a lesser degree that was not statistically significant. However, at 12 weeks, the two groups taking hops were only slightly better (a nonsignificant difference statistically) than the placebo group in terms of hot flashes.

Placebo effects tend to be high in studies of phytoestrogens for menopause symptoms. In the present study, the placebo effect was especially high in the second half, which may explain why the comparative efficacy of the hops formulations appeared to fall off at 12 weeks.

A surprising finding was that the most pronounced effects of hops were seen in the group receiving the lower amount of 8-PN. This may have been a chance occurrence, as the number of women in the study was small. It is possible, however, that when taken in large doses hops interferes with the effect of the body’s natural estrogen. A larger study is warranted to confirm these promising results and to identify the most effective dosage.

Jeremy Appleton, ND, CNS, is a licensed naturopathic physician, certified nutrition specialist, and published author. Dr. Appleton was the Nutrition Department Chair at the National College of Naturopathic Medicine, has served on the faculty at Bastyr University of Natural Health Sciences, and is a former Healthnotes Senior Science Editor and a founding contributor to Healthnotes Newswire. He has worked extensively in scientific and regulatory affairs in the supplement industry and is now a consultant through his company Praxis Natural Products Consulting and Wellness Services.

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