Posted by Chantel M. Contributed by US national library of medicine, National Insitute of health
In a study of "Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis." by Hooper L, Ryder JJ, Kurzer MS, Lampe JW, Messina MJ, Phipps WR, Cassidy A., researchers found that Forty-seven studies (11 of pre-, 35 of post- and 1 of perimenopausal women) were included. In premenopausal women, meta-analysis suggested that soy or isoflavone consumption did not affect primary outcomes estradiol, estrone or SHBG concentrations, but significantly reduced secondary outcomes FSH and LH [by approximately 20% using standardized mean difference (SMD), P = 0.01 and 0.05, respectively]. Menstrual cycle length was increased by 1.05 days (95% CI 0.13, 1.97, 10 studies), and concluded that Isoflavone-rich soy products decrease FSH and LH in premenopausal women and may increase estradiol in post-menopausal women. The clinical implications of these modest hormonal changes remain to be determined.
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