Optimizing Protein Intake in Older Americans with Mobility Limitations

描述（由申请人提供）：蛋白质的推荐膳食供给量（RDA），设定为成年男性和女性每天0.8克/公斤，引起了争论，许多专家主张蛋白质摄入量大大高于RDA，以帮助老年人保持肌肉的活力。目前尚不清楚增加美国老年人的蛋白质摄入量是否会增加骨骼肌质量，肌肉性能和身体功能，他们目前的摄入量低于RDA。我们的第一个目的是确定与RDA（0.8 g/kg/17天）相比，1.3 g/kg/17天蛋白质的给药是否会导致老年男性的瘦体重、最大随意肌肉力量和力量以及自我报告和基于表现的身体功能测量的更大改善。我们的第二个目的是确定是否在瘦体重，最大随意力量和自我报告和基于性能的措施的身体功能在睾酮管理的增益与1.3克蛋白质比与RDA在老年男性的eucaloric饮食。我们将采用2 × 2析因设计进行随机、安慰剂对照、双盲试验.社区居住的男性，65岁或以上，自我报告有活动受限，每日蛋白质摄入量< 0.8 g/kg-17天-1且无睾酮治疗禁忌症，将被随机分配到四组之一：安慰剂注射加蛋白质0.8 g/kg-17天-1;安慰剂注射加蛋白质1.3 g/kg-17天-1;庚酸睾酮125 mg每周加蛋白质0.8 g 7 kg-17天-1;庚酸睾酮125 mg每周加1.3 g蛋白质7 kg-17天-1。治疗持续时间为6个月。主要结果是通过双能X线吸收法测量的从基线到6个月的瘦体重变化。次要结局包括腿部和胸部按压运动中最大随意力量的变化、腿部力量、自我报告（SF-36的身体功能领域）和基于表现的身体功能指标（6分钟步行距离和速度、爬楼梯力量和负重）、疲劳、健康和情感平衡。安全性指标包括估计的GFR、尿钙排泄、血细胞比容、PSA和前列腺检查。几种策略-包装餐，部分控制，经常增援，并通过使用食品合规检查表合规检查-将用于提高遵守饮食处方。仔细的受试者选择、纳入良好试验设计的属性（如随机化、分层和设盲）、基于效应量和把握度考虑的适当样本量、细心的安全性监测以及多学科团队应最大限度地提高成功实现拟议目标的机会，这些目标具有重要的公共卫生和政策意义。 公共卫生相关性：蛋白质的推荐膳食供给量（RDA）引起了很大的争议。许多专家主张老年人的蛋白质摄入量高于目前的RDA。我们将确定在改善瘦体重和身体功能方面，单独摄入更高的蛋白质是否比RDA更安全，更有效，以及这种更高的蛋白质摄入是否会增强对行动不便的老年人的功能促进合成代谢治疗的合成代谢反应。这个问题对美国老年人有着巨大的公共卫生和政策影响。

DESCRIPTION (provided by applicant): The recommended dietary allowance (RDA) for protein, set at 0.8 grams/kg/day for adult men and women, has engendered debate and many experts advocate protein intakes substantially above the RDA to help maintain muscle anabolism in older individuals. It is not known whether increasing protein intake in older Americans, whose current intake is below the RDA, increases skeletal muscle mass, muscle performance and physical function. Our first aim is to determine whether administration of 1.3 g7kg-17day-1 of protein, compared to the RDA (0.8 g7kg-17day-1), will result in greater improvements in lean body mass, maximal voluntary muscle strength and power, and self-reported and performance-based measures of physical function in older men. Our second aim is to determine whether the gains in lean body mass, maximal voluntary strength and self-reported and performance-based measures of physical function during testosterone administration are greater with 1.3 g protein than with the RDA in older men on a eucaloric diet. We will conduct a randomized, placebo- controlled, double blind, and trial using a 2 X 2 factorial design. Community dwelling, men, 65 years or older, who have self-reported mobility limitation, a daily protein intake of < 0.8 g7kg-17day-1 and no contraindications for testosterone therapy, will be randomly assigned to one of four groups: placebo injections plus protein 0.8 g7kg- 17day-1; placebo injections plus protein 1.3g7kg-17day-1; testosterone enanthate 125 mg weekly plus protein 0.8 g7kg-17day-1; testosterone enanthate 125 mg weekly plus 1.3 g protein7kg-17day-1. Treatment duration will be 6 months. The primary outcome is change in lean body mass from baseline to 6 months, measured by dual energy X-ray absorptiometry. Secondary outcomes include change in maximal voluntary strength in leg and chest press exercises, leg power, self-reported (physical function domain of SF-36) and performance-based measures of physical function (6-min walking distance and speed, stair climbing power, and load carrying), fatigue, wellbeing, and affectivity balance. Safety measures include estimated GFR, urinary calcium excretion, hematocrit, PSA, and prostate examination. Several strategies - packaged meals, portion control, frequent reinforcements, and compliance checks by using food compliance checklists - will be used to enhance compliance with dietary prescription. Careful subject selection, incorporation of the attributes of good trial design such as randomization, stratification, and blinding, an appropriate sample size based on consideration of effect size and power, attentive safety monitoring, and a multidisciplinary team should maximize the chances of successful attainment of the proposed aims, which have important public health and policy implications. PUBLIC HEALTH RELEVANCE: The recommended dietary allowance (RDA) for protein has invited a great deal of controversy. Many experts advocate higher levels of protein intake for older individuals than the current RDA. We will determine whether higher protein intakes alone are safe and more effective than the RDA in improving lean body mass and physical function and whether this higher protein intake augments the anabolic response to function promoting anabolic therapy in older persons with mobility limitations. This issue has enormous public health and policy implications for older Americans.