Small black bean (Rhynchosia volubilis) extract ameliorates gut microbial and metabolic perturbation in ovariectomized mice

Phytoestrogen is considered a promising natural remedy for various postmenopausal symptoms. However, most studies have focused on common soybean, Glycine max. Here, for the first time, we evaluated the in vivo effect of a distinct species, small black bean (Rhynchosia volubilis), on ovariectomized mice and investigated its impact on the intestinal microbiota and metabolic status. Ovariectomized mice exhibited significant body weight gain, a typical postmenopausal symptom, and microbial changes, such as decreased alpha-diversity; changes in microbial composition, especially abundances of the families Desulfovibrionaceae and Mogibacteriaceae and genus Dorea; and decreased amino acid and short-chain fatty acid levels. Administration of small black bean extract restores body weight and gut microbial perturbation to levels similar to those observed under normal conditions. Our data suggest that small black bean extract is a potential candidate functional food for treating postmenopausal symptoms via remodeling of the intestinal microbiome.