The relationship of human milk leptin and macronutrients with gastric emptying in term breastfed infants

BACKGROUND: Infants breastfed on demand exhibit a variety of feeding patterns and self-regulate their nutrient intake, but factors influencing their gastric emptying (GE) are poorly understood. Despite research into appetite regulation properties of leptin, there is limited information about relationships between human milk leptin and infant GE. METHODS: Gastric volumes were calculated from ultrasound scans of infants' stomachs (n=20) taken before and after breastfeeding, and then every 12.5 min (median; range: 3-45 min) until the next feed. Skim milk leptin and macro nutrient concentrations were measured and doses were calculated. RESULTS: The leptin concentration was (mean +/- SD) 0.51 +/- 0.16 ng/ml; the leptin dose was 45.5 +/- 20.5 ng per feed. No relationships between both concentration and dose of leptin and time between the feeds (P=0.57; P = 1, respectively) or residual stomach volumes before the subsequent feed (P=0.20; P=0.050) were found. Post-feed stomach volumes (GE rate) were not associated with leptin concentration (P = 0.77) or dose (P = 0.85). CONCLUSION: GE in term breastfed infants was not associated with either skim milk leptin concentration or dose. Further investigation with inclusion of whole-milk leptin and other hormones that affect gastrointestinal activity is warranted.