Gibson R A, Makrides M
Child Nutrition Research Centre, Child Health Research Institute, Flinders Medical Centre, Adelaide, SA, Australia.
Adv Exp Med Biol. 2001;501:375-83. doi: 10.1007/978-1-4615-1371-1_46.
The need for long-chain polyunsaturated fatty acids (LC-PUFA), such as docosahexaenoic acid (DHA, C22:6n3) and arachidonic acid (AA, C20:4n6), in the diet of infants in order to achieve full developmental potential is a matter of intense investigation by several research groups worldwide. It has been widely reported that breast-fed infants perform better on tests that assess neurodevelopmental outcomes than do formula-fed infants. Although human milk contains LC-PUFA that are absent from formula, it is necessary to demonstrate that any beneficial effects of human milk on infant development are purely attributed to the presence of LC-PUFA in human milk and their absence from formula to establish causality. The hypothesis that dietary DHA is associated with developmental outcome needs to be plausible; the effect must be consistent, specific, and independent of confounding factors. The hypothesis is certainly plausible. DHA is avidly incorporated and retained in brain cerebral phospholipids, and a most consistent finding has been the lower level of cerebral DHA in the brains of formula-fed infants (receiving no DHA) relative to those fed human milk (receiving DHA). The formula-fed infants in these studies were generally fed formulas with adequate alpha-linolenic acid levels, and this may indicate a nutritional requirement for preformed DHA. Several studies have compared the effects of breast- and formula-feeding on functional outcomes in preterm and term infants. While many of the outcomes have involved visual testing, others have attempted more global assessments. The results have shown differences in favor of breast-feeding but have been colored by the strong socioeconomic differences between mothers who choose to breast feed and those who choose formula-feeding. Randomized clinical trials involving preterm infants have shown a clear requirement for DHA for full visual and neural development. These results are consistent with primate studies. However, intervention studies with term infants that have attempted to improve the DHA supply of infant formula and hence infant development have not yielded consistent results. Some randomized studies have demonstrated improved visual and developmental indices in supplemented over unsupplemented infants, others have failed to demonstrate an effect. This disparity could be due to methodological and environmental differences. It is also notable that supplemental regimens have not specifically added DHA and have included other LC-PUFA, raising the question as to the specificity of the effect. However, only tissue DHA levels have consistently correlated with outcomes.
为了实现全面的发育潜能，婴儿饮食中对长链多不饱和脂肪酸（LC-PUFA）的需求，如二十二碳六烯酸（DHA，C22:6n3）和花生四烯酸（AA，C20:4n6），是全球多个研究小组深入研究的课题。广泛报道称，母乳喂养的婴儿在评估神经发育结果的测试中比配方奶喂养的婴儿表现更好。虽然母乳中含有配方奶中没有的LC-PUFA，但有必要证明母乳对婴儿发育的任何有益影响完全归因于母乳中LC-PUFA的存在以及配方奶中没有这些成分，以此来确立因果关系。饮食中DHA与发育结果相关的假设需要合理；这种影响必须是一致的、特定的，且不受混杂因素的影响。这个假设当然是合理的。DHA被大量摄取并保留在脑细胞膜磷脂中，一个最一致的发现是，与母乳喂养（摄取DHA）的婴儿相比，配方奶喂养（未摄取DHA）的婴儿大脑中的脑DHA水平较低。这些研究中的配方奶喂养婴儿通常食用的是含有足够α-亚麻酸水平的配方奶，这可能表明对预先形成的DHA有营养需求。几项研究比较了母乳喂养和配方奶喂养对早产和足月婴儿功能结果的影响。虽然许多结果涉及视力测试，但其他研究尝试进行了更全面的评估。结果显示有利于母乳喂养，但选择母乳喂养和配方奶喂养的母亲之间存在巨大的社会经济差异，这给结果带来了影响。涉及早产儿的随机临床试验表明，全面的视力和神经发育显然需要DHA。这些结果与灵长类动物研究一致。然而，试图改善婴儿配方奶中的DHA供应从而促进婴儿发育的足月婴儿干预研究并未得出一致的结果。一些随机研究表明，补充DHA的婴儿比未补充的婴儿在视力和发育指标上有所改善，而其他研究则未能证明有效果。这种差异可能是由于方法和环境的不同。同样值得注意的是，补充方案并非专门添加DHA，而是包含了其他LC-PUFA，这就引发了关于这种影响的特异性的问题。然而，只有组织中的DHA水平一直与结果相关。
