A randomized, double-blind, placebo-controlled, cross-over pilot study on the use of a standardized hop extract to alleviate menopausal discomforts

Phytomedicine. 2010 May;17(6):389-96. doi: 10.1016/j.phymed.2010.01.007. Epub 2010 Feb 18.


Objectives: To examine the efficacy of a hop extract (standardized at 100mug 8-prenylnaringenin per day) for relief of menopausal discomforts.

Methods: A 16-week randomized, double-blind, placebo-controlled, cross-over study was conducted with 36 menopausal women. The participants were randomly allocated to either placebo or active treatment (hop extract) for a period of eight weeks after which treatments were switched for another eight weeks. The Kupperman Index (KI), the Menopause Rating Scale (MRS) and a multifactorial Visual Analogue Scale (VAS) were assessed at baseline, and after eight and sixteen weeks.

Results: After 8 weeks, both active treatment and placebo significantly improved all outcome measures when compared to baseline with somewhat higher average reductions for placebo than for the active treatment. After 16 weeks only the active treatment after placebo further reduced all outcome measures, whereas placebo after active treatment resulted in an increase for all outcome measures. Although, the overall estimates of treatment efficacy (active treatment-placebo) based on linear mixed models do not show a significant effect, time-specific estimates of treatment efficacy indicate significant reductions for KI (P = 0.02) and VAS (P = 0.03) and a marginally significant reduction (P = 0.06) for MRS after 16 weeks.

Conclusions: Whereas the first treatment period resulted in similar reductions in menopausal discomforts in both treatment groups, results from the second treatment period suggest superiority of the standardized hop extract over placebo. Thus, phytoestrogen preparations containing this standardized hop extract may provide an interesting alternative to women seeking relief of mild vasomotor symptoms.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Over Studies
  • Double-Blind Method
  • Female
  • Flavanones / pharmacology
  • Flavanones / therapeutic use*
  • Humans
  • Humulus*
  • Menopause*
  • Middle Aged
  • Pain Measurement / drug effects
  • Phytoestrogens / pharmacology
  • Phytoestrogens / therapeutic use*
  • Phytotherapy*
  • Pilot Projects
  • Plant Extracts / pharmacology
  • Plant Extracts / standards
  • Plant Extracts / therapeutic use*
  • Reference Standards
  • Treatment Outcome


  • Flavanones
  • Phytoestrogens
  • Plant Extracts
  • naringenin