The mechanism of dietary protein modulation of bone metabolism via alterations in members of the GH/IGF axis.

Dietary protein intake as a critical regulatory factor of bone metabolism is a vital element to regulate nutritional status of mammals. Under the action of protease, dietary protein is digested into peptides and free amino acids (FAAs). Then, the metabolites are absorbed by enterocytes and metabolized in various organs of mammals. The dietary protein intake regulates bone metabolism generally via two aspects, dietary itself and signaling transduction. At the dietary level, different kinds of amino acids (AAs) of dietary protein may affect various protein metabolism of bone by regulating proteasome depending on proteolysis and protein synthesis. In addition, dietary protein from multiple sources such as animal, vegetal and healthcare products, presents distinct influences on bone metabolism via regulating calcium balance; At the cellular level, these products can regulate several biological functions via regulating signaling transduction. For example, the significant member of growth hormone/insulin-like growth factor (GH/IGF) axis can be regulated by dietary protein, which has an influence on bone metabolism through different approaches. This review mainly discusses the relationship between dietary protein and GH/IGF axis and illustrates the regulation of bone metabolism in mammals by dietary protein and its signaling transduction.