Associations Among Estrogens, the Gut Microbiome and Osteoporosis

Abstract Purpose of the Review The purpose of this Review was to summarize the evidence on the associations among estrogen status, cellular senescence, the gut microbiome and osteoporosis. Recent Findings Indicate that osteoporosis is a global public health problem that impacts individuals and society. In postmenopausal women, a decrease in estrogen levels is associated with a decrease in gut microbial diversity and richness, as well as increased permeability of the gut barrier, which allows for low-grade inflammation. The direct effects of estrogen status on the association between bone and the gut microbiome were observed in untreated and treated ovariectomized women. In addition to the direct effects of estrogens on bone remodeling, estrogen therapy could reduce the risk of postmenopausal osteoporosis by preventing increased gut epithelial permeability, bacterial translocation and inflammaging. However, in studies comparing the gut microbiota of older women, there were no changes at the phylum level, suggesting that age-related comorbidities may have a greater impact on changes in the gut microbiota than menopausal status does. Summary Estrogens modify bone health not only by directly influencing bone remodeling, but also indirectly by influencing the gut microbiota, gut barrier function and the resulting changes in immune system reactivity.