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

Abstract

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.