Sarcopenia, the age-associated loss of skeletal muscle mass and strength, is a frequent precursor to functional impairment, disability, falls, and loss of independence in the elderly. The prevalence of sarcopenia is high, with ≥ 45% of the U.S. population aged 60 years or older sarcopenic. Some possible causative factors include a decline in muscle protein synthesis, inactivity, hormonal changes, pro-inflammatory conditions, and reactive oxygen species within the muscle mitochondria, which may all be exacerbated by inadequate nutritional intake. Since dietary protein is targeted to muscle and muscle mass represents the largest tissue in the body, protein nutrition plays a significant role in muscle metabolism.