Human milk glycosaminoglycans

Glycosaminoglycans (GAGs) are natural complex linear heteropolysaccharides able to regulate many cellular events and physiological processes due to their strong interactive capacity. This chapter focuses on recent comparative results on structural characterization of human and bovine milk GAGs also providing the first quantitative data on GAGs content both in term and preterm milk during the first month of lactation. Great differences existbetween human and bovine milk. Chondritin sulfate (CS) and dermatan sulfate (DS) differ considerably between the two typs of milk. Hardly any DS is observed in human milk, on the contrary a low-sulfated CS is found in large amounts. Furthermore, structural analysis shows the prevalence of fast-moving heparin that accounts for about 30-40% of total GAGs in both milks. Hyaluronic acid is present in minor accounts. GAG content in human milk is about 7 times higher compared to bovine milk. During the first month of lactation total GAG concentration shows a progressive decrease both in term and preterm milks, with absolute amounts constantly and significantly higher in preterm milk. Breastfed infants ingest consisten amounts of GAGs daily, which, due to their particular structure, may play an active role in the defence mechanisms of the newborn. In fact, undigested human milk GAGs colud play an important role as glycomimetics against several pathogenes (viruses, bacteria and their toxins) through a receptor-like mechanism which prevets their adhesion to intestinal cells. Furthermore, human milk GAGs, due to their well-known antioxidant and antiflammatory activities, may play important defence roles. Once in the colon, they colud be degradated by resident bacteria and, behaving as prebiotics, contribute to stimulate the development of the bifidogenic microflora.