DIETARY PROTEIN REQUIREMENTS OF ELDERLY MEN AND WOMEN

目前所有年龄段成年人的平均蛋白质需要量为0.6克 蛋白质.kg-1.d-1，建议的安全蛋白质摄入量为0.75g Prote.kg-1.d-1,1985年粮农组织/世卫组织/联合国大学联合专家协商会 (世卫组织)和0.8g蛋白质.kg-1.d-1(推荐膳食供给量， 美国国家研究委员会(NRC)在的报告中写道。氮素平衡 (NBAL)是当前标准，也是唯一接受的方法，用于 确定总蛋白质(氮)的需要和摄入量。这两个 世卫组织和国家研究委员会表示，从研究中获得的数据不足 对老年受试者进行实验，以确定蛋白质需要量 自信。因此，目前对老年人的建议是 这在很大程度上是从在年轻人中进行的NBAL研究得出的。然而， 骨质疏松症(与年龄相关的肌肉质量丧失)，以及 老年人的体力活动、食物摄入量和患病频率 在这种情况下，人们可能会导致蛋白质需求的改变 人口。 我们实验室有限的NBAL数据表明，这种蛋白质 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1-13C-亮氨酸平衡研究， 最近提出，老年人对蛋白质的需求是 与更年轻的成年人相似或更少。我们已经证明了 老年妇女坚持低蛋白饮食10周不利 影响脱脂质量、肌肉质量以及肌肉力量和功能。 我们的初步数据现在表明，老年人消费 持续14周提供蛋白质RDA的无脂饮食减去了脂肪 质量和肌肉质量，并增加了身体脂肪。公共卫生 这种适应对蛋白质RDA的影响主要是 未知。 这项研究将首次测试平均蛋白质 7-85岁人群的需求大于18-30岁人群的需求 老人们。女性和男性将被分开研究。双目失明 NBal研究设计将在四个独立的7天NBal试验中使用。 严格的饮食控制将通过给予受试者能量来维持- 平衡菜单含有0.40、0.60、0.80或1.00克蛋白质。kg-1.d- 1.1-13C-亮氨酸平衡研究将在每个蛋白质摄入量进行，以 评估与年龄相关的亮氨酸氧化、利用的差异 氧化、利用、并入白蛋白和表观 蛋白质需要量。内脏蛋白状态的临床标志物将 也是被测量的。研究结果将有助于我们的 了解新陈代谢和对蛋白质的需求，并将 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.