Comparing the effectiveness of sexual education, Lactofem probiotic supplementation, and a combined approach on sexual function, sexual satisfaction, and quality of life in postmenopausal women: a single-blind randomized clinical trial

Sexual dysfunction affects 68–86% of postmenopausal women, impairing quality of life and relationships. Safety concerns with hormone therapy have increased interest in non-hormonal alternatives, yet direct comparative trials remain scarce in Iran. Given the behavioral and supplementation-based nature of the interventions, blinding of participants and the primary investigator was not feasible. However, the data analyst remained blinded to group assignment throughout the statistical analysis phase. This four‑arm parallel randomized controlled trial was conducted in 2025. The data analyst remained blinded to group assignment; however, due to the nature of the interventions, participants and intervention providers could not be blinded. A total of 119 postmenopausal women aged 45–65 years were randomly assigned to four groups using sealed opaque envelopes: Probiotic group ( n = 30): received one 500 mg Lactofem capsule daily containing four bacterial strains (Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus reuteri, and Lactobacillus fermentum) for eight weeks; Sexual Education group ( n = 30): attended five structured weekly 60-minute sessions covering anatomy, physiology, menopausal changes, communication, and sexual skills; Combined group ( n = 30): received both interventions; and Control group ( n = 29): no active intervention. Primary outcomes were sexual function (FSFI), sexual satisfaction (Hudson's ISS), and menopausal symptom burden (MRS), the latter reflecting symptom-related quality of life. Data were analyzed using paired t‑tests, one‑way ANOVA, and Tukey's post‑hoc test in SPSS v.25, with significance set at p<0.05. All three intervention groups showed significant improvements in all outcomes versus baseline (p<0.001), while the control group had no meaningful change. The combined group demonstrated the most pronounced improvements in sexual satisfaction (ISS: -13.67 ± 6.78) and quality of life (MRS: -9.93 ± 4.81). For sexual function (FSFI), although the combined group showed notable improvement (+5.90 ± 2.80), this did not differ significantly from the improvement observed with probiotic supplementation alone (+5.30 ± 2.10), suggesting that the addition of sexual education provided no additional benefit for this specific domain. ANOVA confirmed significant between‑group differences (F=39.131–40.103, p<0.001). Tukey's test showed the combined approach was significantly superior to both single interventions. Effect sizes were large (Cohen's d >1.0) across all active groups. The combined protocol yielded the greatest improvements in sexual satisfaction and quality of life, while for sexual function, probiotic supplementation alone was as effective as the combined approach. These findings suggest that the combined intervention offers additive, domain-specific benefits and represents a well-tolerated, potentially cost-effective non-hormonal strategy for postmenopausal women. Future research should formally evaluate interaction effects and long-term outcomes. It is feasible for primary healthcare in Iran and similar contexts. Longer‑term multicenter studies are recommended. The trial was prospectively registered with the Iranian Registry of Clinical Trials (IRCT) on 13 October 2025 (Registration Number IRCT20250207064680N1).