Gastrointestinal-active oligosaccharides from human milk and functional foods

Keywords: human milk oligosaccharides (HMOs), galacto-oligosaccharides (GOS), konjac glucomannan (KGM), breast milk, baby feces, gastrointestinal metabolization, blood-group specific conjugates, CE-LIF-MSn Oligosaccharides, as present in human milk or supplemented to food, are renowned for their biological activity in the gastrointestinal tract. So far, little is known about the implication of oligosaccharide structures on their gastrointestinal fate. The influence of diet-related oligosaccharides on the postnatal gastrointestinal development and on the establishment of a balanced microflora is of special interest. Therefore, the present research aimed at an advanced understanding of the gastrointestinal metabolization of diet-related oligosaccharides, focusing on infant nutrition. Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was introduced as a sensitive, qualitative and quantitative method for the analysis of individual galactooligosaccharides (GOS) from complex food matrices. The method also showed to be useful for the monitoring and characterization of complex konjac glucomannan (KGM) oligosaccharides, resulting from enzymatic digestion of the KGM polysaccharide andin vitro fermentation with human gut flora. The analysis and identification of human milk oligosaccharides (HMOs) in breast milk and the characterization of oligosaccharides as present in the feces of breast-, formula- and mixed-fed babies was performed by CE-LIF coupled to a mass spectrometer (CE-LIF-MSn). The type of feeding determines the presence of diet-related oligosaccharides in baby feces. For breast-fed babies a gradual change in fecal oligosaccharide profile was found during the first six months postpartum. Three continuous stages of fecal oligosaccharide profiles were defined, comprising the presence of the genetically determined HMO-profile of the breast milk consumed (stage 1), the presence of HMO-units conjugated to blood group determinants from gastrointestinal mucins (stage 2) and predominantly oligosaccharides characteristic for follow-up feeding when solid food is introduced (stage 3). In total, sixteen fecal oligosaccharides, which pointed to the degradation and gastrointestinal metabolization of diet-related oligosaccharides and which were not present in human milk or infant formula, were identified in this research. Monitoring the gastrointestinal fate of diet-related oligosaccharides pointed to an individual-dependent gastrointestinal adaptation to enteral food during the postnatal period.