肌肉衰减综合征是随年龄增加，以肌肉质量、肌肉力量及身体活动能力下降为主要特征的病征，是导致老年人失能、半失能和病死率增加的主要原因。研究表明，营养补充可作为肌肉衰减综合征的重要调整因素。必需氨基酸的补充一方面能促进机体合成类激素和细胞因子增加，促进蛋白质合成；另一方面能通过降低分解类细胞因子减缓蛋白质的分解。β－羟基－β－丁酸甲酯（ HMB ）是亮氨酸的代谢产物，研究显示，补充HMB能改善肌肉衰减。“,”Sarcopenia,characterized by decreased muscle mass,muscle strength,and physical perform-ance,is the main cause of loss of energy,semi-loss of energy and mortality increase in the elderly.Nutritional supplementation is considered an efficient method to reduce muscle atrophy .It has been suggested that sup-plementation of amino acid can enhance protein synthesis via upregulation of anabolic signaling pathways and attenuate proteolysis via downregulation of catabolic signaling pathways .β-hydroxy-β-methylbutyrate ( HMB) ,a metabolite of the branched-chain amino acid leucine,has been investigated by many researchers to improve muscle quality.