Short‐chain milk oligosaccharide levels in human milk and infant plasma

A complex mixture of oligosaccharides comprises approximately 3–19 g/L in human milk. These human milk oligosaccharides (HMO) are thought to play myriad roles in host defense, immunity and potentially neurodevelopment. However, little is known about the relationship between dietary intake of HMO and plasma concentrations of HMO. Short‐chain milk oligosaccharides were quantified in human milk and infant plasma from a total of 55 mother‐infant dyads representing three countries: the Philippines, Oman, and Mexico. Concentrations of 3′sialyllactose (3′SL), 6′sialyllactose (6′SL), 2′fucosyllactose (2′FL) and 3 fucosyllactose (3FL) were determined by HPAEC and LC‐MS/MS. Concentration ranges were determined in human milk (3′SL: 54.3–225 mg/L, 6′SL: 29.3–726 mg/L, 2′FL: 0–3.8 g/L and 3FL: 0.04–1.10 g/L) and infant plasma (3′SL: 0.10–0.78 mg/L, 6′SL: 0.05–0.68 mg/L, 2′FL: 0–2.25 g/L). Regional differences were observed between levels of 2′FL and 3FL in the milk samples. Infant plasma 3′SL was weakly correlated and 6′SL was strongly correlated to mother's milk content. A moderately strong positive correlation was seen between 2′FL in breast milk and plasma samples. These data suggest concentration of HMO in mother's milk can impact plasma levels of HMO in breastfed infants.