New interventions are needed to improve bone health and reduce the risk for osteoporosis and fracture. Dysbiosis is increasingly linked to metabolic abnormalities, although the effect of the microbiota on skeletal health is poorly understood. Previous studies suggest microbiota are detrimental to bone by increasing resorption. In this report, we show that the gut resident microbiota promote bone formation, as well as resorption, with long-term exposure to microbiota resulting in net skeletal growth. Microbiota induce the hormone insulin-like growth factor 1 (IGF-1), which promotes bone growth and remodeling. Short-chain fatty acids (SCFAs), produced when microbiota ferment fiber, also induce IGF-1, suggesting a mechanism by which microbiota affect bone health. Manipulating the microbiome or its metabolites may afford opportunities to optimize bone health and growth
