Uenishi K, Horio H, Manabe S, Sakamoto S
Kagawa Nutrition College, Sakado, Saitama, Japan.
Tokushima J Exp Med. 1993 Dec;40(3-4):147-58.
In order to clarify the effects of dietary proteins on zinc bioavailability during pregnancy, two experiments were carried out. In Experiment 1, changes in zinc retention due to pregnancy (difference in retention between pregnant and nonpregnant animals) during early-mid and late pregnancy were examined in rats fed 10 and 20% egg white diets. Total amounts of retained zinc due to pregnancy were about 1000 micrograms or slightly more, equal to the zinc content in the products of conception at term. However, extra zinc retention during late pregnancy ranged between only 20 to 40% of overall retention, suggesting that almost all zinc retained during early-mid pregnancy moved from the mothers to the fetuses near term. Zinc retention in early-mid and late periods of pregnancy was higher in pregnant than nonpregnant rats, due mainly to increases in intake and bioavailability. In Experiment 2, to examine the effects of quality and quantity of dietary proteins, pregnant rats were fed either 10 or 20% egg white (EW), whole egg (WE), casein (C) and soy protein isolate with or without methionine (SM and S, respectively) diets. Total zinc retention during pregnancy was affected by both zinc and nitrogen intakes, though the former effect was greater than the latter. Because rats fed the EW diets retained dietary zinc efficiently, a relationship between zinc retention (Y, microgram/100 g BW/21 d.) and zinc intake (X, microgram/100 g BW/21 d.) was also examined in the non-EW protein groups, resulting in the following regression equation: Y = 0.471X-1790 (n: 51, r = 0.81, p < 0.001). Dietary protein quality affected the food intake resulting in different zinc intake and retention during pregnancy. Zinc from EW diets was more available than from the other four protein diets, because similar plots for rats fed the 10 and 20% EW diets fell above this line. Reasons for efficient bioavailability of zinc in EW were discussed in connection with the forms of zinc in diets and the pancreatic or intestinal responses to ingested EW.
为了阐明孕期膳食蛋白质对锌生物利用率的影响，进行了两项实验。在实验1中，对喂食10%和20%蛋清日粮的大鼠，检测了妊娠早中期和晚期因妊娠导致的锌潴留变化（妊娠大鼠与未妊娠大鼠的潴留差异）。因妊娠而潴留的锌总量约为1000微克或略多，相当于足月时妊娠产物中的锌含量。然而，妊娠晚期额外的锌潴留仅占总潴留量的20%至40%，这表明妊娠早中期潴留的几乎所有锌在接近足月时从母体转移到了胎儿体内。妊娠大鼠妊娠早中期和晚期的锌潴留高于未妊娠大鼠，主要是由于摄入量和生物利用率的增加。在实验2中，为了研究膳食蛋白质的质量和数量的影响，给妊娠大鼠喂食10%或20%的蛋清（EW）、全蛋（WE）、酪蛋白（C）以及添加或不添加蛋氨酸的大豆分离蛋白（分别为SM和S）日粮。孕期总锌潴留受锌和氮摄入量的影响，尽管前者的影响大于后者。由于喂食EW日粮的大鼠能有效潴留膳食锌，因此在非EW蛋白质组中也检测了锌潴留（Y，微克/100克体重/21天）与锌摄入量（X，微克/100克体重/21天）之间的关系，得出以下回归方程：Y = 0.471X - 1790（n：51，r = 0.81，p < 0.001）。膳食蛋白质质量影响食物摄入量，导致孕期锌摄入量和潴留量不同。EW日粮中的锌比其他四种蛋白质日粮中的锌更易利用，因为喂食10%和20%EW日粮的大鼠的相似图线落在这条线之上。结合日粮中锌的形式以及胰腺或肠道对摄入EW的反应，讨论了EW中锌生物利用率高的原因。
