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Am Fam Physician. 2004;69(3):659

Conventional hormone therapy is effective in relieving climacteric symptoms, but it is usually contraindicated in women who have had breast cancer. Phytoestrogens from plants such as soybeans and red clover can bind to estrogen receptors, resulting in organ-specific estrogenic and antiestrogenic effects. Despite the lack of good scientific evidence of benefit, phytoestrogens have become popular alternative remedies for menopausal symptoms. Nikander and colleagues studied the ability of phytoestrogens to relieve climacteric symptoms in survivors of breast cancer.

Women eligible for the study had no residual malignant disease; were not using tamoxifen, any form of steroid, or medications that could affect climacteric symptoms or the absorption or metabolism of phytoestrogens; and had no risk factors for thromboembolic disease. Participants were selected on the basis of incapacitating symptoms such as hot flushes, night sweats, and sleeplessness, and demonstrated follicle-stimulating hormone (FSH) levels of 30 mIU per mL (30 IU per L) or greater. The 62 women were assigned randomly to phytoestrogen or placebo treatment for three months. The dosage of 114 mg per day of phytoestrogens included 58 percent glycitein, 36 percent daidzein, and 6 percent genistein. Each three-month treatment period was followed by a two-month washout period before three months of treatment with the alternative regimen (crossover design).

Patients were assessed before and after each treatment period. Standardized interviews were used to document symptoms and calculate a Kupperman index for climacteric symptoms. A visual analog scale was developed to assess the severity of symptoms. Other indexes were used to quantify functional abilities, depression, anxiety, self-confidence, general health, nutrition, exercise, alcohol intake, and side effects. Blood samples were collected to measure FSH and sex-hormone levels.

Overall, 56 women completed the study. During the phytoestrogen regimen, circulating levels of phytoestrogens rose 19- to 106-fold, and the Kupperman index reduced by 15.5 percent. During the placebo phase, the Kupperman index reduced by 14.7 percent, and this difference was not significant. When symptoms were examined individually, no specific symptom was relieved by the phytoestrogen therapy. In addition, neither the quality-of-life measures nor the FSH or sex-hormone–related blood levels were significantly changed during the phytoestrogen therapy. Patients had no apparent side effects, and 44.6 percent expressed a preference for the phytoestrogen regimen (not significantly different from placebo).

The authors conclude that a dosage of 114 mg per day of phytoestrogens for three months does not relieve hot flushes or other climacteric symptoms and has no effect on quality of life, ability to work, or psychologic health.

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