Departments of Nutrition Science (MT and WWC) and Statistics (GPM), Purdue University, West Lafayette, IN; the Department of Pediatrics, University of British Columbia, Vancouver, Canada (RE); the Department of Paediatrics and Nutrition Science, University of Toronto, Toronto, Canada (PBP); and the Department of Agricultural, Food and Nutrition Science, University of Alberta, Edmonton, Canada (ROB).
Am J Clin Nutr. 2014 Apr;99(4):891-8. doi: 10.3945/ajcn.112.042325. Epub 2014 Jan 15.
Data on the protein requirements of elderly adults are limited, because it is impractical to conduct repeated nitrogen balance protocols in these vulnerable humans.
This study was designed to determine the dietary protein requirement of elderly women by using the recently developed minimally invasive indicator amino acid oxidation (IAAO) technique.
Six white women aged 80-87 y [mean ± SEM: 82 ± 1 y and body mass index (in kg/m²) 26 ± 2] completed a 3-d protocol 7 times. Each woman consumed an adaptation diet for 2 d and on day 3 consumed a complete test diet with a crystalline amino acid mixture containing 1 of 7 protein intakes (0.1, 0.3, 0.6, 0.9, 1.2, 1.5, or 1.8 g · kg⁻¹ · d⁻¹) tested randomly. A group-based protein requirement was assessed by using a nonlinear mixed model of protein intake and L-[1-¹³C]phenylalanine oxidation. The breakpoint, at which there was no further decline in the rate of appearance of ¹³C in the breath, was used as an index of the mean protein requirement.
The mean protein requirement (95% CI) was 0.85 (0.60, 1.09) g · kg⁻¹ · d⁻¹. This requirement is 29% higher than the current Estimated Average Requirement (EAR) for adults of 0.66 g · kg⁻¹ · d⁻¹ based on the nitrogen balance technique, although the 95% CI includes the current EAR. The corresponding adequate protein allowance of 1.15 (0.77, 1.54) g · kg⁻¹ · d⁻¹ is 44% higher, although the 95% CI includes the Recommended Dietary Allowance (RDA) of 0.80 g · kg⁻¹ · d⁻¹.
Notwithstanding uncertainty about the validity of the use of the IAAO technique to assess protein requirements, the results of this study with octogenarian women suggest that the current EAR and RDA for elderly women may be underestimated. The limitations of this short-term, noninvasive method underscore the need for new research that uses alternative experimental designs and measuring physiologic, morphologic, and health-related outcomes.
老年人的蛋白质需求量数据有限，因为对这些脆弱人群进行重复氮平衡试验是不切实际的。
本研究旨在使用新开发的微创指标氨基酸氧化（IAAO）技术确定老年女性的膳食蛋白质需求量。
6 名年龄 80-87 岁的白人女性[平均±SEM：82±1 岁，体重指数（kg/m²）26±2]共完成 3 天 7 次方案。每位女性先适应 2 天饮食，第 3 天摄入含有 7 种蛋白质摄入量（0.1、0.3、0.6、0.9、1.2、1.5 或 1.8 g·kg⁻¹·d⁻¹）的完全测试饮食，随机摄入其中一种。通过基于蛋白质摄入量和 L-[1-¹³C]苯丙氨酸氧化的非线性混合模型评估基于组的蛋白质需求量。无¹³C在呼吸中进一步出现的转折点被用作平均蛋白质需求量的指标。
平均蛋白质需求量（95%CI）为 0.85（0.60，1.09）g·kg⁻¹·d⁻¹。这一需求量比目前基于氮平衡技术的成年人 0.66 g·kg⁻¹·d⁻¹的估计平均需求量（EAR）高 29%，尽管 95%CI 包含了目前的 EAR。相应的充足蛋白质允许量为 1.15（0.77，1.54）g·kg⁻¹·d⁻¹，高 44%，尽管 95%CI 包含了推荐的膳食允许量（RDA）0.80 g·kg⁻¹·d⁻¹。
尽管使用 IAAO 技术评估蛋白质需求量的有效性存在不确定性，但这项针对 80 岁女性的研究结果表明，目前老年人女性的 EAR 和 RDA 可能被低估了。这种短期、非侵入性方法的局限性突出表明，需要使用替代实验设计和测量生理、形态和健康相关结果的新研究。
