DIETARY PROTEIN REQUIREMENTS OF ELDERLY MEN AND WOMEN

目前，所有年龄段的成年人的平均蛋白质需求量为0.6克 kg-1.d-1，建议安全蛋白质摄入量设定为0.75 g 1985年粮农组织/卫生组织/联合国大学联合专家协商会议 (WHO)和0.8g蛋白质.kg-1.d-1（推荐膳食允许量， RDA）于1989年由美国国家研究理事会（NRC）提出。氮平衡 （NBal）是目前唯一被接受的标准方法，用于 确定总蛋白质（氮）的需要量和允许量。两者 卫生组织和挪威难民理事会指出， 在老年受试者中进行，以确定蛋白质需求， 信心因此，目前对老年人的建议是 很大程度上是从对年轻男性进行的NBal研究中推断出来的。然而， 肌肉减少症（与年龄相关的肌肉质量损失），以及 体力活动、食物摄入量和老年人的疾病频率 人们可能会改变对蛋白质的需求， 人口 来自我们实验室的有限NBal数据表明， 老年人的要求实际上比接受的高出50% 要求。其他研究人员使用1- 13 C-亮氨酸平衡研究， 最近提出，老年人的蛋白质需求是 与年轻人相似或更少。我们已经证明 坚持低蛋白饮食的老年妇女10周不利 影响去脂质量、肌肉质量、肌肉力量和功能。 我们的初步数据显示， 提供14周无脂肪蛋白质RDA的合理热量饮食 质量和肌肉质量，并获得了身体脂肪。公共卫生 这种适应蛋白质RDA的影响主要是 未知 这项研究将首次测试平均蛋白质是否 7-85岁人群需求量大于18-30岁人群， 老年人男女将分别研究。双盲 NBal研究设计将在4项单独的7天NBal试验中使用。 严格的饮食控制将通过给受试者提供能量来维持- 0.40、0.60、0.80或1.00 g蛋白质的平衡菜单。kg-1.d- 1.1- 13 C-亮氨酸平衡研究将在每次蛋白质摄入时进行， 评估年龄相关的亮氨酸氧化、利用 氧化，利用，掺入白蛋白和表观 蛋白质需求内脏蛋白质状态的临床标志物将 也要衡量。研究结果将有助于我们 了解蛋白质的代谢和需求，并将 这对建立老年人蛋白质的RDA至关重要。

The current mean protein requirement for adults of all ages is 0.6 g protein.kg-1.d-1, with a suggested safe protein intake set a 0.75 g protein.kg-1.d-1 in 1985 by the Joint FAO/WHO/UNU Expert Consultation (WHO) and at 0.8 g protein.kg-1.d-1 (the Recommended Dietary Allowance, RDA) in 1989 by the US National Research Council (NRC). Nitrogen balance (NBal) is the current standard, and only accepted, method used to establish total protein (nitrogen) requirements and allowances. Both the WHO and NRC indicated that insufficient data were available from studies done with elderly subjects to determine a protein requirement with confidence. Thus, the current recommendations for elderly people are largely extrapolations from NBal studies done in young men. Yet, sarcopenia (the age-related loss of muscle mass), and changes in physical activity, food intake, and the frequency of disease in elderly people may contribute to an altered protein requirement in this population. Limited NBal data from our laboratory suggest that the protein requirement of elderly people is actually 50% higher than the accepted requirement. Other researchers using 1-13C-leucine balance studies, recently suggested that the protein requirement of elderly people is similar to or less than that of younger adults. We have shown that adherence to a low-protein diet by elderly women for 10 weeks adversely effected fat-free mass, muscle mass, and muscle strength and function. Our preliminary data now indicates that elderly people who consumed eucaloric diets providing the RDA for protein for 14 weeks lost fat-free mass and muscle mass, and gained body fat. The public health implications of this accommodation to the protein RDA are largely unknown. This research will, for the first time, test whether the mean protein requirement of 7-85 year-old people is greater than that of 18-30 year- old people. Women and men will be studied separately. A double-blinded NBal study design will be used during four separate 7 day NBal trials. Strict dietary control will be maintained by giving the subjects energy- balanced menus with either 0.40, 0.60, 0.80 or 1.00 g protein.kg-1.d- 1.1-13C- leucine balance studies will be done at each protein intake to assess age related differences in leucine oxidation, utilization oxidation, utilization, incorporation into albumin and the apparent protein requirement. Clinical markers of visceral protein status will also be measured. The results of the study will contribute to our understanding of the metabolism and requirement for protein, and will be critical to establishing a RDA for protein of elderly people.