Department of Pediatrics, PMU Salzburg, Salzburg, Austria.
Department of Pediatrics, Emma Children's Hospital, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
Nestle Nutr Inst Workshop Ser. 2021;96:86-100. doi: 10.1159/000519394. Epub 2022 May 10.
For preterm and small-for-gestational age infants on enteral nutrition, the best solution is to add human milk fortifier (HMF) to human milk (HM) which is provided by the mother or a milk bank. HMF provides a means to add additional protein, energy, and micronutrients, while maintaining HM as the main source of nutrition. Because of their rapid increase of lean body mass, preterm infants have much higher protein requirements than term infants. Recommendations on protein requirements of preterm infants are available, but protein quality - i.e. the amino acid (AA) profile in HMFs has not been systematically assessed. Present guidelines for enteral nutrition recommend protein intakes around 4 g/kg body weight (BW) for preterm infants <1,500 g, an intake that is not achievable with unfortified HM intakes <200 mL/kg BW/day. It is generally assumed that the AA profile of HM is the best reference for the AA profile of HMF. We calculated advisable intakes of AAs for preterm infants between 400-2,500 g which are based on AA increments of the fetus. Corrections for absorption, inevitable losses, oxidation, and variation of AAs in HM were introduced. Our calculations indicate that extremely low birth weight (ELBW <1,000 g) and very low birth weight (VLBW <1,500 g) infants have substantially higher AA requirements than low birth weight (LBW) infants growing from 1,900 to 2,400 g. In ELBW infants, daily intakes of the different indispensable AAs (IAA) with 4 g of (term) HM protein/kg BW range between 59 and 125% of the respective advisable intakes. Intakes of 7 IAAs and 3 conditionally indispensable AAs (CIAA) are below advisable intakes. On the other hand, with 4 g HM protein per kg BW/day, the IAAs isoleucine and leucine and some dispensable AAs are already supplied in abundance. In VLBW infants, daily intakes of the IAA methionine and 3 CIAAs are still below the advisable intakes. In LBW infants (<2,000 g) receiving 3.5 g HM protein per kg BW daily intakes of 1 IAA and 3 CIAAs would be too low. Preterm infants should receive HMFs which provide adequate amounts of AAs which are needed for their rapid growth and development while avoiding excessive intakes. In particular, very high AA requirements of ELBW infants are a challenge. AA composition of present HMFs for preterm infants should be reconsidered: spiking HMF protein with the AAs which are presently undersupplied or providing targeted AA-based HMF are options to further improve the AA profile in fortifiers.
对于接受肠内营养的早产儿和小于胎龄儿，最好的解决方案是在母亲或母乳库提供的人乳（HM）中添加人乳强化剂（HMF）。HMF 提供了一种添加额外蛋白质、能量和微量营养素的方法，同时保持 HM 作为主要营养来源。由于早产儿的瘦体重迅速增加，他们对蛋白质的需求远高于足月儿。目前有关于早产儿蛋白质需求的建议，但 HMF 中的蛋白质质量（即氨基酸（AA）谱）尚未得到系统评估。目前的肠内营养指南建议，对于体重<1500g 的早产儿，蛋白质摄入量应为 4g/kg 体重，而未强化的 HM 摄入量<200ml/kg BW/天则无法达到这一摄入量。一般认为，HM 的 AA 谱是 HMF 的 AA 谱的最佳参考。我们根据胎儿的 AA 增量计算了 400-2500g 之间早产儿的建议 AA 摄入量。我们引入了对吸收、不可避免的损失、氧化和 HM 中 AA 变化的校正。我们的计算表明，极低出生体重（ELBW<1000g）和超低出生体重（VLBW<1500g）婴儿的 AA 需求比体重从 1900 到 2400g 增长的低出生体重（LBW）婴儿高得多。在 ELBW 婴儿中，每天摄入 4g（足月）HM 蛋白/kg BW 的不同必需氨基酸（IAA）的摄入量为各自建议摄入量的 59%至 125%。7 种必需氨基酸（IAA）和 3 种条件必需氨基酸（CIAA）的摄入量低于建议摄入量。另一方面，对于 4gHM 蛋白/kg BW/天，异亮氨酸、亮氨酸和一些非必需氨基酸已经供应过多。在 VLBW 婴儿中，每天摄入的 IAA 蛋氨酸和 3 种 CIAAs 仍低于建议摄入量。在 LBW 婴儿（<2000g）中，每天接受 3.5gHM 蛋白/kg BW 的摄入量，1 种 IAA 和 3 种 CIAAs 的摄入量过低。早产儿应接受 HMF，其提供的 AA 量应足以满足他们快速生长和发育的需要，同时避免过量摄入。特别是，ELBW 婴儿的高 AA 需求是一个挑战。应重新考虑目前用于早产儿的 HMF 的 AA 组成：用目前供应不足的 AA 对 HMF 进行“加塞”或提供基于 AA 的 HMF 是进一步改善强化剂中 AA 谱的选择。
