A decrease in skeletal muscle mass and strength, a condition called sarcopenia, occurs with aging. Because sarcopenia is one of the main factors of frailty and the need for nursing care in elderly people, effective treatment measures for it should be established. The skeletal muscle protein synthetic response to food/nutrition is blunted in the elderly and is thought to be the cause of sarcopenia. Therefore, stimulating skeletal muscle protein synthesis is the most effective way to prevent and treat sarcopenia in the elderly. A series of studies demonstrated that the oral intake of essential amino acids is important for promoting skeletal muscle protein synthesis in the elderly, and that the use of an essential amino acid mixture with an increased leucine content of up to 40% (Amino L40) more efficiently stimulated skeletal muscle protein synthesis in the elderly. We confirmed that Japanese women (aged >75 years) with sarcopenia who were prescribed 3 g of Amino L40 twice daily and moderate intensity exercise for 3 months gained muscle mass and strength as well as increased walking speed. Thus, use of the nutritional supplement Amino L40 would be an effective strategy to combat sarcopenia.