Effect of soy supplementation on endogenous hormones in postmenopausal women

Aim: The purpose of this study was to investigate the effect of soy supplementation with isoflavones on plasma hormone levels in postmenopausal women. Methods: 16 postmenopausal women (mean age 56.21 +/- 5.01 years) were assigned to 24 weeks of dietary soy supplementation. A defined soy protein amount per day (20 g) with a low dosage of isoflavones (20 mg) was used. Plasma samples were analyzed for estradiol, FSH, LH, prolactin, testosterone and DHEAS. Results: After 24 weeks of soy supplementation, plasma levels of estradiol did not increase. Gonadotropins, prolactin and the measured plasma androgens remained unchanged. We did not see any significant treatment effects. Conclusions: In the postmenopausal hypoestrogenic situation, soy protein consumption with low isoflavones does not influence endogenous hormone levels of estradiol and gonadotropins. Copyright (C) 2003 S. Karger AG, Basel.