Protein Metabolism in the Elderly

Aging is associated with a gradual loss in protein mass and physical function due to metabolic dysregulations that result in an imbalance between net rates of protein synthesis and degradation. Aging affects protein and amino acid metabolism in many tissues, including skeletal muscle, splanchnic tissues, cardiovascular tissues, skin, and brain. The characteristic loss of muscle protein that occurs during aging is predominantly due to a decline in sensitivity of the protein synthetic processes that respond to acute anabolic stimuli such as nutrition and exercise. Nutritional intake, physical activity, and endocrine function tend to decline with aging and further contribute to the decline in metabolic function and physical health. Metabolic stressors including oxidative and nitrositive reactive species and the accumulation of posttranslational proteins modifications are central to the age-related dysregulation of protein and amino acid metabolism and the development of sarcopenia and frailty.