Murton Andrew J
MRC/ARUK Centre for Musculoskeletal Ageing Research,Division of Nutritional Sciences,School of Biosciences,Sutton Bonington Campus,The University of Nottingham,LE12 5RD,UK.
Proc Nutr Soc. 2015 Nov;74(4):387-96. doi: 10.1017/S0029665115000130. Epub 2015 Mar 31.
The underlying aetiology of sarcopenia appears multifaceted and not yet fully defined, but ultimately involves the gradual loss of muscle protein content over time. The present evidence suggests that the loss of lean tissue in the elderly is exacerbated by low dietary protein intake. Moreover, acute stable-isotope-based methodologies have demonstrated that the muscle anabolic response to a given amount of protein may decline with age, a phenomenon that has been termed anabolic resistance. Although the mechanism responsible for the inability of muscle to mount a satisfactory anabolic response to protein provision with increasing age is presently unknown, it does not appear due to impaired digestion or absorption of dietary protein. Rather, the issue could reside with any combination of: a diminished delivery of amino acids to peripheral tissues, impaired uptake of amino acids into muscle cells, or an inability of amino acids to elicit intracellular events pivotal for anabolism to occur. Despite the presence of anabolic resistance to dietary protein, present evidence suggests that protein supplementation may be able to overcome these issues, particularly when combined with resistance exercise programmes. As such, protein supplementation may prove to be an effective approach to delay the loss of muscle mass with age and has led to calls for the recommended daily intake of protein to be increased for the elderly population.
肌肉减少症的潜在病因似乎是多方面的，尚未完全明确，但最终涉及肌肉蛋白质含量随时间的逐渐流失。目前的证据表明，老年人膳食蛋白质摄入量低会加剧瘦组织的流失。此外，基于急性稳定同位素的方法表明，随着年龄增长，肌肉对一定量蛋白质的合成代谢反应可能会下降，这一现象被称为合成代谢抵抗。尽管目前尚不清楚随着年龄增长肌肉无法对蛋白质供应产生令人满意的合成代谢反应的原因，但这似乎不是由于膳食蛋白质消化或吸收受损所致。相反，问题可能在于以下任何一种组合：输送到外周组织的氨基酸减少、氨基酸进入肌肉细胞的摄取受损，或氨基酸无法引发对合成代谢至关重要的细胞内事件。尽管存在对膳食蛋白质的合成代谢抵抗，但目前的证据表明，补充蛋白质可能能够克服这些问题，特别是与抗阻运动计划相结合时。因此，补充蛋白质可能被证明是延缓肌肉质量随年龄流失的有效方法，并导致有人呼吁增加老年人群的蛋白质每日推荐摄入量。
