Advanced Characterization of Biofunctional Human Milk Oligosaccharides by Mass Spectrometry and Complementary Methods

Human milk oligosaccharides (HMOs) are soluble carbohydrates and represent the 3rd most abundant molecular fraction in human milk (HM). The biofunction potential of HMOs is broad and includes prebiotic, anti-infective and anti-inflammatory effects. A better characterisation of individual HMO-variations in early life could be key to further unravel their impact on the healthy development of breast fed infants. In the course of this thesis, novel analytical methods were successfully developed and deployed to quantify relevant HMO-structures present in HM. By application of these cutting edge (primarily) mass spectrometry (MS) based approaches, even formerly difficult to distinguish HMO-isomers (e.g. 2’-FL, 3-FL, 3’-SL, 6’-SL, LNT, LNnT, LNFP I, II,III and V) could be accurately analysed. HMO-profiles were yielded for more than 1000 European HM specimens collected at 6 weeks, 6month and 12 month after birth. As a result, unexpected insights about early life HMO-variations were unveiled. For example, a surprising increase or decrease of specific trioses (3’-SL, 3-FL, and DFL versus 6’-SL and 2’-FL) over the investigated course of lactation was observed. Also, the presence of the galactosyllactoses 3’-GL and 6’GL could be confirmed in > 75 % of investigated HM samples. Most intriguingly, further evidence for two new HM (sub) groups with different phenotypes of alpha 1,2 fucosylated HMOs could be confirmed. Future research is warranted to explore the biological significance of these new findings. Nevertheless, they may be useful to inspire new generations of formulations for early life nutrition with HMO profiles much closer to their natural blueprint, human milk.