Oligosaccharide Diversity in Milks: A Comparative Analysis of Human, Mammalian, and Plant-Based Sources

Abstract

This study conducts a comprehensive comparative analysis of oligosaccharide composition and glycosidic linkage patterns across eight milk types: human, bovine (cow and buffalo), goat, Gaddi sheep, camel, donkey/mare, and selected plant-based alternatives. Utilizing advanced analytical techniques, including Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry (UPLC-MS/MS), High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD), Liquid Chromatography–Quadrupole Time-of-Flight Mass Spectrometry (LC-QTOF-MS), Nuclear Magnetic Resonance (NMR), and exoglycosidase linkage mapping, we profiled and quantified the oligosaccharide content and linkage diversity. Results revealed that human milk possesses the highest complexity, with ∼35–40 g/L of oligosaccharides comprising over 160–240 unique structures, including critical fucosylated and sialylated variants for neonatal immunity and gut health. Goat (42 oligosaccharides) and cow milk (35 oligosaccharides) followed in complexity, while camel (34 oligosaccharides) and Gaddi sheep (approx. 16 oligosaccharides) exhibited more limited profiles. Donkey/mare milk shared notable similarities with human milk in lactose levels and structural roles, though with lower oligosaccharide diversity. In contrast, plant-based milks, such as almond and soy, lacked complex mammalian-type oligosaccharides, primarily containing simpler plant-derived oligosaccharides like raffinose and stachyose, typically with α-galactosyl linkages. Functional insights demonstrated that specific OS from goat and donkey milk exhibited prebiotic potential and pathogen inhibition. This study offers critical biochemical insights for designing optimized infant formulas and enhancing plant-based milk alternatives by replicating the beneficial oligosaccharide patterns found in mammalian milk