Human Milk Macronutrients and Bioactive Molecules and Development of Regional Fat Depots in Western Australian Infants during the First 12 Months of Lactation

We investigated associations between intakes of human milk (HM) components (macronu-trients and biologically active molecules) and regional fat depots development in healthy term infants(n= 20) across the first year of lactation. Infant limb (mid-arm and mid-thigh) lean and fat areas wereassessed by ultrasound imaging at 2, 5, 9 and 12 months of age. Concentrations of HM total protein,whey protein, casein, adiponectin, leptin, lysozyme, lactoferrin, secretory IGA, total carbohydrates,lactose, HM oligosaccharides (total HMO, calculated) and infant 24-h milk intake were measured,and infant calculated daily intakes (CDI) of HM components were determined. This pilot studyshows higher 24-h milk intake was associated with a larger mid-arm fat area (p= 0.024), higherbreastfeeding frequency was associated with larger mid-arm (p= 0.008) and mid-thigh (p< 0.001)fat areas. Lysozyme (p= 0.001) and HMO CDI (p= 0.004) were time-dependently associated withthe mid-arm fat area. Intakes of HM components and breastfeeding parameters may modulateinfant limb fat depots development during the first year of age and potentially promote favorabledevelopmental programming of infant body composition; however, further studies are needed to