Soy Nutrition Institute
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May 18, 2016

Soy isoflavones alleviate hot flashes

Symptoms associated with menopause include hot flashes, night sweats, and vaginal dryness, with 50% to 80% of menopausal women reporting hot flashes or night sweats.  Medical treatments for these symptoms are available, including hormone replacement therapy. However, as much as 50% of women in Western countries choose to use complementary therapies, including plant-based therapies.  In a meta-analysis published in the Journal of the American Medical Association that included 18 clinical trials, Franco et al. (1) found that dietary phytoestrogens statistically significantly reduced hot flash frequency although the effects were relatively modest, approximately 1 hot flash per day above and beyond the placebo response.  While it is welcomed news to see the efficacy of isoflavones recognized in a medical journal, the analysis actually underestimated the effects of isoflavones.  The reason is that the authors of this meta-analysis didn’t sub-analyze the data according to the genistein content of the isoflavone supplements used in the clinical trials.  A 2012 meta-analysis showed quite clearly that  supplements that mimic the isoflavone profile of the soybean, which means genistein is the predominate isoflavones, are about twice as potent as soy isoflavone supplements with a low genistein content (2).

  1. Franco OH, Chowdhury R, Troup J, Voortman T, Kunutsor S, Kavousi M, Oliver-Williams C, and Muka T. Use of plant-based therapies and menopausal symptoms: A systematic review and meta-analysis. JAMA 2016;315:2554-63.

  1. Taku K, Melby MK, Kronenberg F, Kurzer MS, and Messina M. Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause 2012;19:776-790