Castillo-Durán Carlos, Weisstaub Gerardo
Institute of Nutrition and Food Technology, Universidad de Chile, Macul 5540, Santiago, Chile.
J Nutr. 2003 May;133(5 Suppl 1):1494S-7S. doi: 10.1093/jn/133.5.1494S.
Zinc deficiency limits growth in young children, and in animal models it also affects fetal growth. In animals, the effect of severe zinc deficiency on growth is evident. However, controlled trials of zinc supplementation during pregnancy in humans have not demonstrated consistent effects on weight at birth and/or duration of gestation. Those studies that have identified a positive effect of zinc on fetal growth were performed on low-socioeconomic or migrant groups in industrialized countries or in countries where diet and living conditions are improving. In contrast, in studies conducted either on populations with minimal risk of zinc deficiency or those suffering from multiple and severe nutritional deficiencies, no effects have been found. The potential confounding factors that may help explain the contradictory results include the following: age of pregnant women; presence of digestive diseases, other nutritional deficiencies, phytates or other factors that affect bioavailability; timing and duration of zinc supplementation and compliance with supplements. Few studies of zinc supplementation were conducted on infants that were born small for their gestational age or preterm; in this case, a positive effect on growth was shown. A study of zinc supplementation during pregnancy found reduced risk of diseases (diarrhea or impetigo) in small-for-gestational-age but not preterm infants. A second study demonstrated reduced mortality in small-for-gestational-age infants. We conclude that supplementation trials during human pregnancy do not provide conclusive evidence for a beneficial effect of zinc supplementation despite the experimental evidence that zinc deficiency may retard fetal growth or shorten pregnancy. However, early zinc supplementation in low birth weight or small-for-gestational-age infants reveals an effective improvement in growth, which suggests a prenatal depletion or insufficient zinc intake to support catch-up growth postnatally.
锌缺乏会限制幼儿的生长，在动物模型中，它还会影响胎儿的生长。在动物身上，严重锌缺乏对生长的影响很明显。然而，关于人类孕期补充锌的对照试验尚未证明对出生体重和/或妊娠期有一致的影响。那些发现锌对胎儿生长有积极作用的研究是在工业化国家的低社会经济群体或移民群体中进行的，或者是在饮食和生活条件正在改善的国家进行的。相比之下，在对锌缺乏风险极小的人群或患有多种严重营养缺乏症的人群进行的研究中，未发现有影响。可能有助于解释这些矛盾结果的潜在混杂因素包括：孕妇年龄；是否存在消化系统疾病、其他营养缺乏、植酸盐或其他影响生物利用度的因素；锌补充的时间和持续时间以及对补充剂的依从性。很少有关于对小于胎龄儿或早产儿补充锌的研究；在这种情况下，显示出对生长有积极作用。一项关于孕期补充锌的研究发现，小于胎龄儿而非早产儿患疾病（腹泻或脓疱病）的风险降低。另一项研究表明小于胎龄儿的死亡率降低。我们得出结论，尽管有实验证据表明锌缺乏可能会阻碍胎儿生长或缩短妊娠期，但人类孕期补充试验并未提供确凿证据证明补充锌有有益效果。然而，对低出生体重或小于胎龄儿早期补充锌显示出生长有有效改善，这表明产前锌消耗或锌摄入量不足，无法支持出生后的追赶生长。
