Supplementary Material for: The Study of Breast Milk IGF-1, Leptin, Ghrelin and Adiponectin Levels as Possible Reasons of High Weight Gain in Breast-Fed Infants

Background: Excessive consumption of protein that leads to increased blood levels of insulin-like growth factor-1 (IGF-1) is an important risk factor for high growth velocity and obesity in formula-fed infants. However, it is not clear whether these factors can explain the high growth velocity in breast-fed infants. Aim: To study the possible links between the growth velocity in breast-fed infants and the levels of protein, IGF-1 and other hormones, which regulate energy homeostasis, in mothers' breast milk. Methods: We studied 103 mother-infant pairs. Their daily breast milk intake and level of IGF-1, leptin, ghrelin, adiponectin, protein and fat in breast milk were measured at 1, 2 and 3 months of lactation. The infant group was divided into three subgroups of low, normal and high weight gain tertiles. Results: The breast milk consumed by the infants with high weight gain contained higher levels of IGF-1 than that consumed by those with low weight gain at all periods studied (p = 0.032 at 3 months of lactation), and ghrelin levels were higher at 1 and 2 months and leptin levels at 2 and 3 months of lactation (p < 0.05). A positive correlation was observed between the breast milk IGF-1 level and infant weight gain (r = 0.294, p = 0.043). Total daily breast milk, fat and hormone intake was also higher in the high weight gain group compared to the low weight gain group. Conclusion: One of the reasons for the high growth velocity in breast-fed infants may be the enhanced levels of the studied hormones in breast milk.

背景：过度摄入蛋白质可导致血液胰岛素样生长因子-1（IGF-1）水平升高，是配方喂养婴儿生长速度过快与肥胖的重要危险因素。但目前尚不清楚此类因素是否可解释母乳喂养婴儿的快速生长现象。
研究目的：探讨母乳喂养婴儿的生长速度与母亲母乳中蛋白质、IGF-1及其他调控能量稳态的激素水平之间的潜在关联。
研究方法：本研究纳入103对母婴。在泌乳第1、2、3个月时，测定婴儿每日母乳摄入量，以及母乳中IGF-1、瘦素（leptin）、胃饥饿素（ghrelin）、脂联素（adiponectin）、蛋白质与脂肪的水平。依据婴儿体重增长三分位将其分为低、正常、高体重增长三个亚组。
研究结果：在所有观测时段内，高体重增长组婴儿摄入的母乳IGF-1水平显著高于低体重增长组（泌乳第3个月时p=0.032）；泌乳第1、2个月时母乳胃饥饿素水平更高，泌乳第2、3个月时母乳瘦素水平更高（均p<0.05）。母乳IGF-1水平与婴儿体重增长呈正相关（r=0.294，p=0.043）。高体重增长组婴儿的每日母乳总摄入量、脂肪及激素摄入量亦高于低体重增长组。
研究结论：母乳喂养婴儿生长速度过快的潜在原因之一，可能为母乳中上述研究涉及的激素水平升高。