Glycine metabolism in skeletal muscle: implications for metabolic homeostasis

Purpose of review The review summarizes the recent literature on the role of glycine in skeletal muscle during times of stress. Recent findings Supplemental glycine protects muscle mass and function under pathological conditions. In addition, mitochondrial dysfunction in skeletal muscle leads to increased cellular serine and glycine production and activation of NADPH-generating pathways and glutathione metabolism. These studies highlight how glycine availability modulates cellular homeostasis and redox status. Summary Recent studies demonstrate that supplemental glycine effectively protects muscles in a variety of wasting models, including cancer cachexia, sepsis, and reduced caloric intake. The underlying mechanisms responsible for the effects of glycine remain unclear but likely involve receptor-mediated responses and modulation of intracellular metabolism. Future research to understand these mechanisms will provide insight into glycine's therapeutic potential. Our view is that glycine holds considerable promise for improving health by protecting muscles during different wasting conditions.