Fucosylated human milk oligosaccharides vary between individuals and over the course of lactation

Specific human milk oligosaccharides, especially fucosylated neutral oligos accharides, protect infants against specific microbial pathogens. To study the concentrations of individual neutral oligosaccharides during lactation, a total of 84 milk samples were obtained from 12 women at 7 time periods d uring weeks 1-49 postpartum. The neutral oligosaccharides from each sample were isolated, perbenzoylated, resolved, and quantified by reversed-phase h ighperformance liquid chromatography, The resultant oligosaccharide peaks, identified by co-elution with authentic standards and mass spectrometry, ra nged in size from trito octasaccharides, The total concentration of oligosa ccharides declined over the course of lactation; the mean concentration at 1 year was less than half that in the first few weeks postpartum One of the 12 donors produced milk fucosyloligosaccharides that were essentially devo id of alpha1,2 linkages (but contained alpha1,3- and alpha1,4-linked fucose ) until late in lactation, consistent with the nonsecretor phenotype, In mi lk samples from the remaining 11 donors, fucosyloligosaccharides containing alpha1,2-linked fucose were prevalent, and their profiles were distinct fr om those of fucosyloligosaccharides devoid of alpha1,2-linked fucose, The r atio of al,2-linked oligosaccharide concentrations to oligosaccharides devo id of al,2-1inked fucose changed during the first year of lactation from 5: 1 to 1:1, Furthermore, the absolute and the relative concentrations of indi vidual oligosaccharides varied substantially, both between individual donor s and over the course of lactation for each individual. The patterns of mil k oligosaccharides among individuals suggest the existence of many genotype subpopulations. This variation in individual oligosaccharide concentration s suggests that the protective activities of human milk could also vary amo ng individuals and during lactation.