Q&A

Red clover extracts not effective for hot flushes

J Fam Pract. 2003 November;52(11):828-848
By
Andrea Gordon, MD
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  • BACKGROUND Women in countries where the diet contains large amounts of soy report a much lower incidence of menopausal symptoms than women in Western countries.1 Since isoflavones cause selective estrogen receptor stimulation, they are hypothesized to be the active ingredients in soy. Isoflavones from other plants, such as red clover, are similarly marketed for the treatment of menopausal symptoms, often without any basis from well-designed research.
  • POPULATION STUDIED: Postmenopausal women were recruited from the community in 3 states. Women consuming more than 2 alcoholic drinks a day or soy products more then once a week were excluded. After exclusions, 252 women with at least 35 hot flushes per day and with a follicle-stimulating hormone level of >30 mIU/mL were enrolled. More than 80% of subjects were white.
  • STUDY DESIGN AND VALIDITY: Subjects meeting inclusion criteria who were at least 80% compliant after a 2-week run-in period were randomized to receive 1 of 2 supplements or placebo. The supplements, Promensil (82 mg of total isoflavones per day) and Rimostil (57 mg of total isoflavones per day), differed slightly in their proportions of individual isoflavones. Women were contacted by telephone at 1, 4, and 8 weeks to assess effects and concerns and were asked to keep hot-flush frequency diaries. Final evaluation was done at a clinic visit at 12 weeks.
  • OUTCOMES MEASURED: Outcomes measured were the number of hot flushes, scores on the Greene Climacteric quality-of-life scale, and urinary excretion of isoflavones.
  • RESULTS Promensil, Rimostil, and placebo all reduced hot flushes by 34% to 41%, without any significant differences between the treatment groups. Scores on the Greene Climacteric quality-of-life scale improved significantly in all 3 groups, but again without significant differences between the groups. Researchers found no significant correlation of change in the number of hot flushes with changes in total isoflavone excretion. Per-protocol (analyzing only those who took their pills) results were similar to the intention-to-treat analysis. Significant adverse effects were not seen in any of the groups.
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PRACTICE RECOMMENDATIONS

Both red clover extracts and placebo equally reduce the frequency of hot flushes. Providers should encourage patients to avoid spending money on supplements and instead add soy to their diet. In general, however, if patients are already convinced that something works, don’t discourage them.

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