Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, PA.
J Nutr. 2019 Jul 1;149(7):1282-1287. doi: 10.1093/jn/nxz056.
Sampling times and study duration impact estimates of kinetic parameters and variables including total body stores (TBS) and disposal rate (DR) when compartmental analysis is used to analyze vitamin A kinetic data.
We hypothesized that inclusion of dietary intake (DI) of vitamin A as an additional input would improve confidence in predictions of TBS and DR when modeling results appear to indicate that studies are not long enough to accurately define the terminal slope of the plasma retinol isotope response curve.
We reanalyzed previously published data on vitamin A kinetics monitored over 52 d in 7 US and 6 Chinese adults (means: 56 y, BMI 26.6 kg/m2, 38% males), adding an estimate for vitamin A intake [2.8 µmol/d (mean RDA)] as an input during application of the Simulation, Analysis and Modeling software.
Use of a model with 1 extravascular compartment (1 EV), as in the original analysis, resulted in predictions of vitamin A intake that were higher than physiologically reasonable; inclusion of intake data in a model with 2 extravascular compartments (2 EV DI) resulted in more realistic estimates of intake and DR. Specifically, predictions of DR by the 2 EV DI (versus 1 EV) model were 2.10 compared with 12.2 µmol/d (US) and 2.21 compared with 5.13 µmol/d (Chinese). Predictions of both TBS [2056 compared with 783 µmol (US) and 594 compared with 219 µmol (Chinese)] and days of vitamin A stores [981 compared with 64 d (US) and 269 compared with 43 d (Chinese)] were higher using the new approach.
Inclusion of vitamin A intake as additional data input when modeling vitamin A kinetics can compensate for less-than-optimal study duration, providing more realistic predictions of vitamin A TBS and DR. This approach advances the application of compartmental analysis to the study of vitamin A and, potentially, other nutrients.
当使用房室分析来分析维生素 A 动力学数据时，采样时间和研究持续时间会影响动力学参数和变量的估计，包括总体体储（TBS）和处置率（DR）。
我们假设，当模型结果表明研究时间不够长，无法准确定义血浆视黄醇同位素反应曲线的终末斜率时，将膳食摄入（DI）作为维生素 A 的附加输入，将有助于提高对 TBS 和 DR 的预测的置信度。
我们重新分析了之前发表的在 7 名美国和 6 名中国成年人中监测 52 天的维生素 A 动力学数据（平均值：56 岁，BMI 26.6kg/m2，38%男性），在应用 Simulation、Analysis and Modeling 软件时，将维生素 A 摄入量的估计值（2.8µmol/d[平均 RDA]）作为输入添加到模型中。
使用原始分析中具有 1 个血管外隔室（1EV）的模型，导致维生素 A 摄入量的预测值高于生理合理值；在具有 2 个血管外隔室（2EVDI）的模型中包含摄入量数据，导致更现实的摄入量和 DR 估计值。具体而言，2EVDI（与 1EV 相比）模型对 DR 的预测值分别为 2.10µmol/d（美国）和 2.21µmol/d（中国），分别为 12.2µmol/d（美国）和 5.13µmol/d（中国）。使用新方法，TBS[2056µmol（美国）和 594µmol（中国）]和维生素 A 储存天数[981d（美国）和 269d（中国）]的预测值均更高。
在建模维生素 A 动力学时，将维生素 A 摄入量作为附加数据输入，可以补偿研究时间不足的问题，更真实地预测维生素 A 的 TBS 和 DR。这种方法推进了房室分析在维生素 A 及其他营养素研究中的应用。
