EVALUATION OF MINERAL ABSORPTION IN INFANTS FED HUMAN MILK OR FORMULA

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。enfamilil和enfamilil Lipil富含棕榈油，其脂肪混合物由40%的棕榈酸和43%的油酸组成。然而，与人乳相比，植物油中的棕榈酸主要在sn-1和sn-3位置而不是sn-2位置酯化(1)，就像在人乳中发现的棕榈酸一样（2,3）。在sn-1和sn-3位置酯化的棕榈酸在消化过程中容易被水解，形成不溶性钙皂，导致脂肪和钙的吸收比sn-1和sn-3位置棕榈酸较少的配方更差（4-6）。在Enfamil配方中加入互化棕榈油（在sn-2位置有更大的棕榈酸）是否会比目前的配方更好地吸收脂肪和钙还不清楚。此外，目前的enfamili配方中的钙吸收是否与人乳提供的钙吸收相似，还没有直接研究。现在市场上的配方奶粉，像许多婴儿配方奶粉一样，棕榈酸主要在sn-1和sn-3位置酯化，而不是在sn-2位置，就像在人乳中发现的棕榈酸一样。第二种配方在sn-2位置含有更多的棕榈酸（sn-1和sn-3位置较少），使其更类似于母乳。由于它的成分更接近母乳，我们认为它是一种安全的产品，只是在评估对钙吸收的影响。从FDA的层面来看，这种变化被认为是次要的，例如，不需要像重大变化那样需要进行全套研究来允许这种变化。最后，之前的耐受性研究已经证明了该配方的安全性。由于配方的修改和改进是由人乳的营养成分和功能营养成分指导的，因此美赞臣营养品公司（MJN）确认enfamilil Lipil与人乳相比功能充足是很重要的。公布的母乳中钙的平均吸收量为58 +/- 17%，平均钙含量为41毫克/100千卡，每天的钙吸收量为24.6 +/- 15 （SD）毫克/100千卡。enfamili的高钙含量（78毫克/100千卡）实际上弥补了较少的钙吸收量（38 +/- 16%）。因此，每日钙吸收量为29.6 +/- 12.5 mg/100 kcal，所有这些值都反映了使用经典平衡技术而不是双稳定同位素产生的值。先前的研究表明，通过双同位素吸收方法，我们可以预计Enfamil Lipil的SD值为8而不是12.5，与互化棕榈油脂混合物（IPO-EL）的Enfamil Lipil的SD值约为40 +/- 10。与配方奶不同的是，母乳中钙的含量在不同的母亲之间也有很大的差异，除了测量到的吸收分数的差异之外，各组之间的吸收分数应该更相似。因此，将人乳钙绝对吸收的更广泛的经典平衡与公式（标准差为15,8和10）估计的双同位素方法方差合并，估计总体方差为11.4，以计算本研究在α水平为0.05的情况下提供80%功率所需的n。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Enfamil and Enfamil Lipil are rich in palm olein, with a fat blend comprised on 40% palmitic acid and 43% oleic acid. However, in contrast to human milk, the palmitic acid in vegetable oils is predominantly esterified in the sn-1 and sn-3 position rather than the sn-2 position (1), as is the case for palmitic acid found in human milk (2,3). Palmitic acid that is esterified in the sn-1 and sn-3 position tends to be hydrolyzed during digestion and made available to form insoluble calcium soaps, resulting in poorer fat and calcium absorption than is seen with formulas with less palmitic in the sn- 1 and sn-3 position (4-6). Whether the inclusion of interesterified palm olein (with greater palmitic acid in the sn-2 position) in an Enfamil formulation would results in better fat and calcium absorption than the current formulation is not known. Moreover, whether calcium absorption in the current Enfamil formulation is similar to that provided by human milk has not been studied directly. The formula on the market now, like many infant formulas, has the palmitic acid predominantly esterified in the sn-1 and sn-3 position rather than the sn-2 position, as is the case for palmitic acid found in human milk. The second formula has more palmitic acid in the sn-2 position (less in the sn-1 and sn-3 positions), making it more comparable to human milk. As it is even closer in composition to human milk, we consider it to be a safe product and are merely assessing the effect on calcium absorption. From an FDA level, this change is considered minor and does not, for example, require the full set of research studies to allow the change as would be needed for a major change. Finally, previous tolerance studies have been done to demonstrate the safety of the formula. Since modifications and improvements of formulations have been guided by the nutrient content and functional nutrient composition of human milk, it is important that Mead Johnson Nutritionals (MJN) confirm the functional adequacy of Enfamil Lipil compared to human milk. The mean published absorption of calcium from breast milk is 58 +/- 17% with a mean calcium content of 41 mg/100 kcal, yielding a daily calcium absorption of 24.6 +/- 15 (SD) mg/100 kcal. The higher calcium content of Enfamil (78 mg/100 kcal) actually compensates for less fractional calcium absorption (38 +/- 16%). Therefore daily calcium absorption is 29.6 +/- 12.5 mg/100 kcal. All of these values reflect values generated using classic balance techniques rather than dual stables isotopes. Previous studies have shown that by using dual isotope absorption methods we can expect SD for Enfamil Lipil of 8 rather than 12.5 and SD values for Enfamil Lipil with interesterified palm olein fat blend (IPO-EL) of about 40 +/- 10. In contrast to formula, human milk calcium content also varies significantly between mothers in addition to variation in measured fractional absorption, which would be expected to be more similar between groups. Thus, the wider classical balance for absolute calcium absorption from human milk was pooled with the estimated double isotope method variance from the formulas (standard deviations of 15, 8, and 10) to estimate the population variance of 11.4 to calculate the n needed for this study to provide 80% power with an alpha level of 0.05.