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Flash: Plant Estrogens Don't Help

Postmenopausal women with vasomotor symptoms derived no more benefit from phytoestrogens than from placebo.

Phytoestrogens, commonly found in edible plants such as soybeans and red clover, bind weakly to the estrogen receptor and are marketed widely as a nonhormonal treatment alternative for hot flashes. But, do they work? In this double-blind trial, 62 postmenopausal symptomatic women were randomized to receive phytoestrogens (isoflavonoids, 114 mg/day) or placebo for 3 months; after a 2-month washout period, the women crossed over to the other arm for 3 months. All women previously had been treated for breast cancer and complained of incapacitating hot flashes, night sweats, and sleeplessness.

Among the 56 women who completed the study, 25 (44.5%) preferred the phytoestrogens, 15 (26.8%) preferred the placebo (nonsignificant difference), and 16 (28.6%) had no preference. Mean hot-flash score (Kupperman index), working-capacity index, and mood index did not differ significantly after phytoestrogen treatment compared with placebo, nor did liver-enzyme levels, hormone parameters, BMI, or blood pressure. The only significant difference was an increase in serum phytoestrogen concentration after phytoestrogen treatment.

Comment: The results from this well-designed, crossover trial prove that phytoestrogens are ineffective in treating menopausal symptoms. The impressive placebo effect underscores the importance of having data from trials with placebo arms before making clinical recommendations for the treatment of vasomotor symptoms.

— Sandra Ann Carson, MD

Published in Journal Watch Women's Health August 6, 2003

Citation(s):

Nikander E et al. A randomized placebo-controlled crossover trial with phytoestrogens in treatment of menopause in breast cancer patients. Obstet Gynecol 2003 Jun; 101:1213-20.

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