Structural and compositional changes in human milk proteins, lipids, and carbohydrates according to maternal metabolic profile: a multimodal characterization approach in a cohort of mothers from Northeastern Mexico.

Human milk (HM) contains key macronutrients (proteins, lipids, and carbohydrates) essential for infant development; however, compositional differences do not necessarily reflect equivalent structural properties. This study analyzed HM samples collected at 1 and 3 months postpartum from mothers with normal weight (NW), overweight or obesity (OWO), and OWO with gestational diabetes (OWO + D) to evaluate associations between maternal metabolic status and HM composition, morphology, and thermodynamic behavior. Macronutrient concentrations were quantified, and structural and thermal properties were assessed using DLS, fluorescence microscopy, FTIR, SDS-PAGE, and nanoDSC. Although protein and fat concentrations did not differ significantly between groups, OWO + D samples exhibited enlarged casein micelles, reduced fat globule size and distinct thermal profiles, indicating altered supramolecular organization. Lactose was higher in OWO + D, while total HMOs were highest in NW and lowest in OWO + D. Overall, these results highlight that maternal metabolic status may influence HM biophysical properties beyond bulk composition.