2′-fucosyllactose: an abundant, genetically determined soluble glycan present in human milk

Abstract

[EN]Lactose isthe preeminent soluble glycan in milk and a significant source of energy for most newborn mammals. Elongation of lactose with additional monosaccharides gives rise to a varied repertoire of free soluble glycans such as 2′-fucosyllactose (2′-FL), which is the most abundant oligosaccharide in human milk. In infants, 2′-FL is resistant to digestion and reaches the colon where it is partially fermented, behaving as soluble prebiotic fiber. Evidence also suggests that portions of small soluble milk glycans, including 2′-FL, are absorbed, thus raising the possibility of systemic biological effects. 2′-FL bears an epitope of the Secretor histo-blood group system; approximately 70–80% of all milk samples contain 2′-FL, since its synthesis depends on a fucosyltransferase that is not uniformly expressed. The fact that some infants are not exposed to 2′-FL has helped researchers to retrospectively probe for biological activities of this glycan. This review summarizes the attributes of 2′-FL in terms of its occurrence in mammalian phylogeny, its postulated biological activities, and its variability in human milk.