Bone and the microbiome

Abstract The gut microbiota (GM) could be regarded as a separate highly metabolic active organ harboring many more genes than the human genome and, in contrast to the human genome, the microbiome is adapting rapidly to environmental changes. Animal studies using germ-free mice, antibiotics, probiotics, or prebiotics have collectively shown that the GM is an important regulator of bone homeostasis in rodents. The major known pathways for the GM to regulate bone homeostasis include involvement of the immune system, intestinal permeability, short-chain fatty acids, calcium absorption, and serum insulin-like growth factor 1. Two recent placebo controlled randomized clinical trials demonstrated that probiotic treatment has the capacity to regulate bone mass also in humans. The term osteomicrobiology is used for the rapidly emerging research field of the role of the microbiota in bone health and we anticipate that this research field will continue to expand in the coming years.