DESIGN: Literature research using PubMed and the Cochrane controlled trials register.
SETTING: None.
PATIENT(S): None.
INTERVENTION(S): None.
MAIN OUTCOME MEASURE(S): None.
RESULT(S): Six systematic reviews and meta-analyses of 25 randomized, controlled trials (RCTs) assessing the use of
phytoestrogens for the treatment of the climacteric syndrome were identified. Systematic reviews of RCTs show contradictory results, and meta-analyses demonstrate no statistically significant reduction of vasomotor symptoms for
phytoestrogens. Individual RCTs report significant reductions in vasomotor symptoms for red clover and soy
phytoestrogens. In selected patient populations, such as in women with early natural postmenopause and mild to moderate vasomotor symptoms, a systematic review of five RCTs found a significant reduction of
hot flashes in five out of five RCTs. Twenty-two case-control and cohort studies examined the incidence of
breast cancer among women with and without a diet high in
phytoestrogens. A meta-analysis of 21 studies found a significantly reduced incidence of
breast cancer among past
phytoestrogen users. RCTs document beneficial effects of
phytoestrogens on surrogate parameters such as bone mineral density, vasodilation, platelet aggregation,
insulin resistance, and serum concentrations of
triglycerides,
high-density lipoprotein, and
low-density lipoprotein. None of the available RCTs documents a protective effect of
phytoestrogens for the clinical end points of
breast cancer,
bone fracture, or cardiovascular events.
CONCLUSION(S): Based on the available evidence,
phytoestrogens should only be used in selected women, i.e., those presenting with mild to moderate vasomotor symptoms in early natural postmenopause. None of the compounds investigated so far have been proven to protect against
breast cancer,
bone fracture, or
cardiovascular disease.