Bales Connie W, Ritchie Christine S
Geriatric Research, Education and Clinical Center, Durham VA Medical Center and Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Annu Rev Nutr. 2002;22:309-23. doi: 10.1146/annurev.nutr.22.010402.102715. Epub 2002 Jan 4.
The progression of the aging process leads to a decreased margin of homeostatic reserve and a reduced ability to accommodate metabolic challenges, including nutritional stress. Nutritional frailty refers to the disability that occurs in old age owing to rapid, unintentional loss of body weight and loss of lean body mass (sarcopenia). Sarcopenia, a loss of muscle mass and strength, contributes to functional impairment. Weight loss is commonly due to a reduction in food intake; its possible etiology includes a host of physiological and nonphysiological causes. The release of cytokines during chronic disease may also be an important determinant of frailty. In addition to being anorectic, cytokines also contribute to lipolysis, muscle protein breakdown, and nitrogen loss. Whereas the multiple causes of nutritional frailty are not completely understood, clinical interventions for weight loss, sarcopenia, and cytokine alterations have been used with modest success.
衰老过程的进展导致体内稳态储备的余地减小，应对包括营养应激在内的代谢挑战的能力降低。营养性衰弱是指由于体重快速、非故意减轻以及瘦体重（肌肉减少症）丧失而在老年时出现的残疾。肌肉减少症，即肌肉质量和力量的丧失，会导致功能障碍。体重减轻通常是由于食物摄入量减少；其可能的病因包括许多生理和非生理原因。慢性病期间细胞因子的释放也可能是衰弱的一个重要决定因素。细胞因子除了具有食欲抑制作用外，还会促进脂肪分解、肌肉蛋白质分解和氮流失。虽然营养性衰弱的多种原因尚未完全了解，但针对体重减轻、肌肉减少症和细胞因子改变的临床干预措施已取得一定成效。
