| A total of more than 1000 microbes, such as bacteria, fungi, viruses, and archaea in the human gut, together constitute the human gut microbiome. Intestinal microorganisms play an important role in the regulation of human mucosal barrier function, immune function, endocrine function, digestive function, and energy metabolism. In recent years, it has been found that intestinal microorganisms can also regulate bone metabolism. The ways that intestinal microorganisms affect bone quality mainly include stimulating osteoclast formation by promoting the expression of inflammatory factors, regulating the activation level of osteoblasts and osteoclasts by acting on the endocrine axis, and releasing metabolites to form an acidic intestinal environment which is conducive to calcium absorption. In addition, intestinal microorganisms are also involved in the regulation of bone loss caused by the decrease of estrogen level. Therefore, intestinal microorganisms have two-way regulation on bone quality, which are briefly summarized in this paper. |