Bone is a dynamic, living organ that plays structural, protective, and functional roles in the body. It is made up of a protein matrix and mineral deposits. The matrix provides a framework, and the mineral deposits provide hardness and strength. Remodeling is a process of removing old bone and rebuilding new. Remodeling is ongoing throughout life, continually working to maintain bone homeostasis and responding to injury, inflammation, and mechanical load. The process is regulated by several hormones, cytokines, and growth factors, and it requires many nutrients for building and maintenance.