Phytoestrogens in clinical practice: a review of the literature.
OBJECTIVE
To review clinical studies assessing the effect of phytoestrogen supplementation on the signs and symptoms of the climacteric syndrome and on the incidence of breast cancer, cardiovascular disease, and skeletal fractures.


METHODS
Literature research using PubMed and the Cochrane controlled trials register.


METHODS
None.


METHODS
None.


METHODS
None.


METHODS
None.


RESULTS
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.


CONCLUSIONS
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.
Tempfer
Clemens B
CB
Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria. clemens.tempfer@meduniwien.ac.at <clemens.tempfer@meduniwien.ac.at>
Bentz
Eva-Katrin
EK
Leodolter
Sepp
S
Tscherne
Georg
G
Reuss
Ferdinand
F
Cross
Heide S
HS
Huber
Johannes C
JC
D001943:Breast Neoplasms / Q000517:prevention & control*; D015331:Cohort Studies; D004967:Estrogens / Q000097:blood; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000627:therapeutic use; D008593:Menopause / Q000187:drug effects*; D008875:Middle Aged; D048789:Phytoestrogens / Q000627:therapeutic use*; D010936:Plant Extracts / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic
D004967:Estrogens; D007529:Isoflavones; D048789:Phytoestrogens; D010936:Plant Extracts