The effect of a soy-rich diet on urogenital atrophy: a randomized, cross-over trial

To evaluate the effect of a soy-rich diet on urogenital symptoms, vaginal health index, and vaginal cytology in perimenopausal and postmenopausal women.

Thirty-six perimenopausal and postmenopausal women (mean age 52.5+/-5.1 years) participated in a randomized, cross-over trial with two 12-week diet periods and two 4-week washout periods before and between treatments. The study diet consisted of a control diet (soy-free diet) and an isocaloric soy-rich diet (25 g soy protein in various forms of soy food containing more than 50 mg/day of isoflavones substituted for an equivalent amount of animal protein). Subjects were assessed for urogenital symptoms, vaginal health index, vaginal pH and vaginal cytology. The single physician and the single cytopathologist were blinded with regard to onset, period and randomization number. Statistical analyses were performed using paired t-test or Wilcoxon Signed Ranks Test, significance was set as P<0.05.

Good compliance to the diet was shown by the significant elevation of serum levels of daidzein and genistein during the soy-rich diet period. The symptoms of urge incontinence and vaginal dryness had significantly increased after 12-week of soy-free diet. All other urogenital symptoms did not change in both periods. The vaginal health index, the vaginal pH, the karyopyknotic index, and the maturation value were not significantly changed in both periods.

A soy-rich diet did not relieve the urogenital symptoms or restore the vaginal epithelium or improve the vaginal health in perimenopausal and postmenopausal Thai women.