HUMAN MILK OLIGOSACCHARIDES: THE SECRET WEAPON FOR NEONATES AND INFANTS

Krishnendu Sarkar and Maitrayee Banerjee Mukherjee*

ABSTRACT

The human milk oligosaccharides (HMOS) range from 3 to 32 sugars in size, and differ greatly in composition from those of any other mammal. HMOs account for a notable quantity of human milk, similar to the quantity of total protein. The HMOs are ―prebiotic‖ agents that selectively encourage the growth of beneficial (probiotic) organisms. In addition, the HMOS and their protein conjugates are recognized as pathogen-binding inhibitors that function as soluble ―decoy‖ receptors for pathogens that have an affinity for binding to oligosaccharide receptors expressed on the infant’s intestinal surface. These diverse milk glycans serve many functions, including protection and development ranging from selectively enriching gut bifidobacteria; prophylactically binding bacteria, viruses, and toxins; promoting the immune system; and enhancing intestinal epithelial barrier function. Mothers vary in the specific structures of HMOS in their milk as a result of genetic differences similar to blood group types. This variation in HMOS composition, unlike blood group types, does not create incompatability, so that all mothers may be considered ―universal donors.‖ Rather, the variation in HMOS composition among mothers is thought to promote human survival as pathogens differ in their affinity for binding to specific oligosaccharides. Protection by some forms of HMOS has been shown in relation to diarrhea caused by specific pathogens and HIV. The apparent differences in lactose and HMOS composition of preterm milk requires further investigation.

Keywords: Human milk, oligosaccharides, immunity, pathogens.