Characteristics of Oligosaccharide Composition in Chinese Human Milk

To analyze the impact of different regions, lactation times, and blood group genotypes on the oligosaccharide composition of healthy lactating mothers’ breast milk from representative regions of China, and to explore the compositional characteristics of oligosaccharides in Chinese human milk, in this longitudinal cohort study, the concentrations of 23 oligosaccharides in breast milk samples from 109 healthy mothers at three lactation stages in six cities in east, west, north and south China were analyzed by ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UPLC-MS-MS). Besides, the attribution of breast milk to blood group genotypes was investigated. The results showed that concentrations of total oligosaccharides and total fucosylated neutral oligosaccharides were significantly higher in samples from Kunming, Jinan and Shenzhen than those from Beijing, Baotou and Xining, and the concentrations of 3-fucosyllactose (3-FL), lactodifucotetraose (LDFT) and lacto-N-neodifucohexaose Ⅱ (LNnDFH-Ⅱ) were significantly lower in samples from Baotou than those from Shenzhen, Jinan and Beijing, respectively. The concentrations of eight neutral oligosaccharides and four acidic oligosaccharides showed a significant decreasing trend with lactation time, whereas 3-FL concentration increased significantly, and the concentrations of LDFT and LNnDFH-Ⅲ also increased but not significantly. The concentrations of two monofucosylhexasaccharides were the highest in 1-month-old mature milk, and then remained unchanged or decreased slightly as lactation progressed. Based on oligosaccharide types, it was inferred that the majorblood group genotype of lactating mothers was Se⁺Le⁺ for all the six cities. In this genotype, the concentrations of lacto-N-difucohexaose-Ⅱ (LNDFH-Ⅱ), LNDFH-Ⅰ & LNnDFH-Ⅰ, 6’-sialyllactose (6’-SL) and sialyllacto-tetrasaccharide c (LSTc) were higher and the concentrations of 18 other oligosaccharides were lower than in other genotypes. This study provides scientific theoretical guidance for precise estimation of the intake of breast milk oligosaccharides by infants and young children at the early life stage.