Hayamizu Kohsuke, Aoki Yuma, Izumo Nobuo, Nakano Makoto
Department of Pharmacy, Yokohama University of Pharmacy, Matano-cho 601, Totsuka-ku, Yokohama, Kanagawa 245-0066, Japan.
J Clin Biochem Nutr. 2021 Jan;68(1):32-36. doi: 10.3164/jcbn.20-79. Epub 2020 Jul 31.
The indicator amino acid oxidation (IAAO) method is a recently developed method to determine the protein requirement and is particularly useful for analyzing human subjects because of its minimal invasiveness. IAAO study is performed using two-phase regression analysis, with the break-point between these phases being the estimated average requirement. However, this method requires that the break-point lie within a certain range in advance, which is in practice difficult. Recently, the change-point regression model (CPRM) has been proposed to be more effective for two-phase regression analysis. There is also a need to re-evaluate the value corresponding to the recommended dietary allowance. Calculation of the recommended dietary allowance requires data on the average requirement and the inter-individual variability of this requirement. However, no inter-individual variability values have been reported in the IAAO method. The aim of this study was thus to estimate the inter-individual variation in protein requirement using CPRM. From seven IAAO studies, the inter-individual variability was estimated as a coefficient of variation of about 20%. The coefficient of variation of the protein requirement determined by IAAO study was wider than the ordinary coefficient of variation obtained from the nitrogen balance test.
指示性氨基酸氧化（IAAO）法是一种最近开发的用于确定蛋白质需求量的方法，由于其微创性，对分析人类受试者特别有用。IAAO研究采用两阶段回归分析进行，这两个阶段之间的断点即为估计平均需求量。然而，该方法要求断点预先处于一定范围内，而在实际中这很难做到。最近，有人提出变化点回归模型（CPRM）在两阶段回归分析中更有效。此外，还需要重新评估与推荐膳食摄入量相对应的值。计算推荐膳食摄入量需要平均需求量以及该需求量个体间变异性的数据。然而，在IAAO法中尚未报告个体间变异性值。因此，本研究的目的是使用CPRM估计蛋白质需求量的个体间变异。从七项IAAO研究中，个体间变异性估计为变异系数约20%。通过IAAO研究确定的蛋白质需求量变异系数比通过氮平衡试验获得的普通变异系数更宽。
