Pinto Bean Supplementation Modulates Gut Microbiota and Improves Markers of Gut Integrity in a Mouse Model of Estrogen Deficiency

Abstract

Background: Emerging research suggests that changes in gut microbiota play a key role in menopause-related diseases by modulating gut health. Objectives: This study investigated the effects of pinto bean (PB) supplementation on gut integrity in an estrogen-deficient mouse model. Methods: Sixty 3-mo-old female C57BL/6J mice were injected with either sesame oil (vehicle) or vinylcyclohexene diepoxide (VCD, 160 mg/kg) for 30 d to induce estrogen deficiency. Mice were then randomly assigned to 2 dietary groups (n = 15/group): control (AIN-93M) or AIN-93M + 10% (wt/wt) PB for 16 wk. Ovarian failure was confirmed by uterine weight and serum follicle-stimulating hormone (FSH). Gut health was assessed by measuring tight junction proteins, β-glucuronidase activity, short-chain fatty acids (SCFAs), and 16S microbiota composition. PB was evaluated for its estrogenic effects by molecular docking analysis of the identified polyphenols against estrogen receptor (ER)-α and ER-β. Data were analyzed by 2-way analysis of variance, with estrogen status (VCD) and diet as factors followed by post hoc tests when significant (P < 0.05) interaction effect was observed. Results: VCD significantly (PVCD < 0.05) reduced relative uterine weight (∼35%) and increased serum FSH (∼60%), confirming estrogen reduction. PB restored jejunal Cldn1 (Pdiet × VCD < 0.05) in VCD-treated mice and significantly increased (Pdiet=0.010) β-glucuronidase activity (∼25%). PB enriched some beneficial bacteria genera (i.e., Bifidobacterium, Bacteroides, Dubosiella, and Lactobacillus) and increased fecal acetic, propionic, n-butyric, and total SCFAs by 2-fold compared with those on the control diet. Molecular docking analysis identified sinapic and ferulic acid as phytoestrogens in PB with high binding affinity for ERs. Conclusions: PB supplementation improves gut microbial diversity and integrity in estrogen deficiency, offering potential benefits for menopause-related gut health.