Genistein supplementation alleviates bone damage by regulating gut microbiota composition and metabolism in obesity and estrogen decline

Postmenopausal women face an elevated risk of osteoporosis due to decreased estradiol secretion. Obesity is also a prevalent disease during menopause, but the impact on bone health is understudied. Genistein (GEN) is a soy-derived isoflavone that has beneficial effects on a variety of age-related diseases, but the exact role of GEN in bone health in hypoestrogenism and obesity-induced stress remains to be elucidated. This study employed an ovariectomized (OVX) mouse model subjected to a high-fat diet to simulate postmenopausal obesity and investigate the effects of GEN intake on bone metabolism. Bone mass alterations and metabolic function were evaluated using micro-CT imaging, biochemical markers, and histopathological staining. The homeostasis of the bone matrix was further assessed through primary bone marrow cell differentiation assays, western blotting, and quantitative real-time PCR (qRT-PCR). Additionally, intestinal barrier protein expression, 16S rRNA gene sequencing, and untargeted metabolomics were integrated to examine GEN's impact on gut structure, microbiota composition, and fecal metabolic profiles. Our findings indicated that diet-induced obesity (DIO) exacerbated OVX-induced osteopenia in mice, whereas GEN supplementation significantly mitigated bone loss and restored balanced differentiation among osteoblasts, adipocytes, and osteoclasts. Furthermore, GEN improved metabolic abnormalities associated with obesity. It also preserved intestinal barrier integrity by maintaining tight junction proteins and mucus levels, thereby reducing systemic inflammation. The results of 16s rDNA gene sequencing showed that GEN alleviated intestinal microbiota dysbiosis and increased the abundance of beneficial bacteria <i>g-Dubosiella</i> and <i>g-Blautia</i> in feces. Moreover, metabolomics analysis showed that GEN intervention could alleviate lipid peroxidation and promote primary bile acid biosynthesis. In conclusion, long-term intake of GEN can regulate gut microbiota composition and metabolism, maintain intestinal barrier function, ameliorate pathological metabolic abnormalities, and ultimately prevent obesity and estrogen hypoestrogenic-induced osteopenia. These findings provide novel insights into how GEN intake and soy diet prevent osteoporosis.