Hambidge K Michael, Krebs Nancy F, Westcott Jamie E, Miller Leland V
Section of Nutrition, Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
J Pediatr. 2006 Nov;149(5 Suppl):S64-8. doi: 10.1016/j.jpeds.2006.06.054.
Zinc (Zn) nutrition is of special practical importance in infants and young children, however relatively little is known about maturation and comparative aspects of Zn absorption. The principal objective of this paper is to compare Zn absorption of term infants, preterm infants, and adults on low phytate diets. Existing data derived from using Zn stable isotopes as extrinsic labels for an entire day were modeled with saturation kinetic analysis (saturable response model). When adjusted for differences in length of small intestine, the efficiency of Zn absorption for both term (4 months) and preterm (33 weeks post-conception) infants was comparable with that for adults, suggesting early maturation of mechanisms that regulate absorption. However, infant intestinal lengths were shorter, and Zn absorptive capacity was proportionately less. Reduced capacity was matched by lower Zn requirements for normal term infants. This favorable match, however, did not occur in the preterm infant because of relatively high Zn requirements. Although intestinal conservation of endogenous Zn in these preterm infants was appropriate in relation to the quantity of Zn absorbed, it was not optimal for achieving the retention required. Normal homeostatic mechanisms in the premature infant prevented efficient absorption of the quantity of Zn required or/and optimal conservation of endogenous Zn.
锌（Zn）营养对婴幼儿具有特殊的实际重要性，然而，关于锌吸收的成熟过程和比较方面的了解相对较少。本文的主要目的是比较足月儿、早产儿和成年人在低植酸饮食条件下的锌吸收情况。使用锌稳定同位素作为全天的外源性标记所获得的现有数据，采用饱和动力学分析（饱和反应模型）进行建模。当根据小肠长度差异进行调整后，足月儿（4个月）和早产儿（孕33周）的锌吸收效率与成年人相当，这表明调节吸收的机制早期就已成熟。然而，婴儿的肠长度较短，锌吸收能力相应较低。正常足月儿较低的锌需求量与较低的吸收能力相匹配。然而，由于早产儿对锌的需求量相对较高，这种良好的匹配并未出现。尽管这些早产儿肠道对内源性锌的保留与吸收的锌量相关是合适的，但对于实现所需的锌潴留并非最佳。早产儿正常的体内平衡机制阻碍了所需锌量的有效吸收和/或内源性锌的最佳保留。
