Wasantwisut E
Institute of Nutrition, Mahidol University Salaya, Phutthamonthon, Nakhon Pathom, Thailand.
Southeast Asian J Trop Med Public Health. 1997;28 Suppl 2:78-82.
Previous studies have provided strong evidence that protein-energy malnutrition, deficiencies of iron and iodine early on in life led to compromised growth and cognitive functions in young children. Recently, a growing body of knowledge indicated that other micronutrients also play a role in young child development. Severe as well as marginal vitamin A efficiency were shown to lead to an increased risk of morbidity and mortality in children. A meta-analysis of vitamin A intervention trials indicated an overall reduction of 23% in all-cause mortality rate. Delayed growth, especially stunting, was reported in children with clinical signs of vitamin A deficiency. In addition, deficiency of zinc, which is essential for DNA and protein synthesis, leads to growth failure and delayed secondary sexual maturation in man and animals. Preterm infants appear to benefit from zinc administration in terms of growth and development. Supplementation studies in infants and older children revealed that those who manifested overt zinc deficiency through either clinical or biochemical indicators showed an improvement in linear growth and occasionally, an increase in weight gain. Zinc may also play a major role in brain function based on strong evidence from experimental animals. Zinc deficiency gestation in mice, rats, rhesus monkeys caused impaired learning, reduced attention and poor memory in their offspring. Data in humans are few and inconclusive. With respect to brain function alone, other nutrients such as docosahexaenoic acid (DHA, 22:6 n-3 fatty acid) improve visual acuity and mental development in small-for-gestational-age infants, folate supplementation during pregnancy prevents neural tube defect in infants, selenium deficiency in animals affects activities of brain enzymes necessary for brain development and function. Although evidence is accumulating that micronutrients other than iron and iodine may be important for physical growth and brain development in young children, more well-controlled studies in humans are needed. Critical issues to be considered include: single vs multiple limiting nutrients, critical period of deficiency, responsive indicators and variables that may affect the results as environmental, psychological and social factors.
以往的研究提供了强有力的证据，表明生命早期的蛋白质 - 能量营养不良、铁和碘缺乏会导致幼儿生长发育和认知功能受损。最近，越来越多的知识表明，其他微量营养素在幼儿发育中也发挥着作用。严重以及边缘性维生素A缺乏均显示会增加儿童发病和死亡风险。一项维生素A干预试验的荟萃分析表明，全因死亡率总体降低了23%。有维生素A缺乏临床症状的儿童出现生长发育迟缓，尤其是发育迟缓。此外，锌对于DNA和蛋白质合成至关重要，锌缺乏会导致人和动物生长发育不良以及第二性征发育延迟。早产儿在生长发育方面似乎受益于锌的补充。对婴儿和大龄儿童的补充研究表明，那些通过临床或生化指标表现出明显锌缺乏的儿童，其线性生长得到改善，偶尔体重增加也会增多。基于实验动物的有力证据，锌在脑功能中可能也起着重要作用。小鼠、大鼠、恒河猴孕期锌缺乏会导致其后代学习能力受损、注意力下降和记忆力不佳。关于人类的数据较少且尚无定论。仅就脑功能而言，其他营养素如二十二碳六烯酸（DHA，22:6 n - 3脂肪酸）可改善小于胎龄儿的视力和智力发育，孕期补充叶酸可预防婴儿神经管缺陷，动物缺硒会影响大脑发育和功能所需的脑酶活性。尽管越来越多的证据表明，除铁和碘之外的微量营养素可能对幼儿的身体生长和脑发育很重要，但仍需要在人类中进行更多严格对照的研究。需要考虑的关键问题包括：单一营养素与多种受限营养素、缺乏的关键时期、反应指标以及可能影响结果的变量，如环境、心理和社会因素。
