THE OLIGOSACCHARIDE COMPOSITION OF HUMAN-MILK - TEMPORAL AND INDIVIDUAL VARIATIONS IN MONOSACCHARIDE COMPONENTS

Oligosaccharides are an important component of human milk, but little is known about variations in their composition. The aim of this study was to determine the temporal and inter-individual variations in carbo hydrate composition of human milk during the first 3 months of lactati on. Serial milk samples of 10 mothers (eight fullterm and two preterm births) were analyzed to determine the concentration of lactose and th ree monosaccharide components derived from the non-lactose carbohydrat e: sialic acid, N-acetylglucosamine, and fucose. In full-term milk, si alic acid and N-acetylglucosamine were found to decrease significantly (p < 0.05) from weeks 1 to 13 postnatally. On average (mean +/- SD), sialic acid decreased by 71% (from 879 +/- 157 to 256 +/- 82 mg/L; p < 0.05) and N-acetylglucosamine by 56% (from 1,459 +/- 282 to 646 +/- 2 14 mg/L; p < 0.05), while fucose decreased by only 35% (from 660 +/- 1 92 to 432 +/- 180 mg/L; p > 0.05). On average, lactose concentration i ncreased by 17% over the same period, from 55.4 +/- 4.2 g/L in week 1 to 64.9 +/- 2.3 g/L at 3 months. Preterm milk contained higher concent rations of each component, but temporal changes were similar to those seen in full-term milk. Apart from temporal changes, there were large inter-individual differences in oligosaccharide composition: fucose va ried fourfold, sialic acid threefold, and N-acetylglucosamine twofold among women at the same stage of lactation. The changes observed may s imply reflect the aging of the cells responsible for milk secretion, b ut they are also consistent with a programmed adaptation of the milk c omposition to the needs of the infant.