The Effect of Dietary Soy Supplementation Compared to Estrogen and Placebo on Menopausal Symptoms: a Randomized Controlled Trial

Objectives: To compare the effects of daily ingestion of dietary soy supplementation, low-dose hormone therapy (HT) and placebo on psychological, somatic and urogenital symptoms in postmenopausal women.

Study Design: A double-blind, randomized, controlled trial. Sixty healthy, symptomatic, postmenopausal women of 40-60 years of age were allocated to use dietary soy supplementation (containing 90 mg of isoflavone) or HT (1mg estradiol and 0.5mg norethisterone acetate) or placebo.

Main Outcome Measures: the Menopause Rating Scale (MRS) was used to assess menopausal symptoms at baseline and after 16 weeks of treatment. Intention-to-treat analyses were performed using the chi-square test, Fisher's exact test, the Kruskal-Wallis non-parametric test and analysis of variance (ANOVA).

Results: No statistically significant differences were found between the groups with respect to baseline clinical and sociodemographic characteristics. The psychological, somatic and urogenital symptoms analyzed in the MRS improved during treatment in all the groups, except for urogenital symptoms in the placebo group in which no significant changes were detected. Comparison between groups revealed a statistically significant improvement in somatic symptoms (hot flashes and muscle pain) in the users of HT (-45.6%) and dietary soy supplementation (-49.8%). Urogenital symptoms (vaginal dryness) improved significantly in HT users (-38.6%) and in users of the dietary soy supplementation (-31.2%). There was no statistically significant difference between the groups with respect to overall MRS score or to scores obtained in the psychological symptoms subscale.

Conclusion: Dietary soy supplementation may constitute an effective alternative therapy for somatic and urogenital symptoms of the menopause.