SIALIC-ACID IN HUMAN-MILK AND INFANT FORM ULAS

Objective: Sialic acid (N-acetylneuraminic acid, NANA) is an essential component of mucins, glycoproteins and gangliosides and therefore imp ortant for the function of cell membranes, membrane receptors and the normal development of the brain. The capacity of the metabolic pathway for the synthesis of sialic acid from glucose and other carbohydrate sources in preterm infants and term-born neonates is currently unknown . Methods: In the present study the overall nutritional sialic acid su pply of infants was analysed by means of HPLC-based determination of s ialic acid concentrations in a total of 51 human milk samples obtained from nursing mothers at different stages of lactation. The data were compared with 3 commercial preterm infant formulas, 7 adapted infant f ormulas, 11 partially adapted infant formulas, 4 follow-up and 2 soyba sed formulas. Results: The sialic acid concentration in colostrum and transitory human milk was 1300+/-322 mg/l. After the 10th day of lacta tion the concentration dropped to 983+/-455 mg/l (p<0.01). Preterm inf ant formulas contained 197+/-31, adapted formulas 190+/-31, partially adapted formulas 100+/-33, follow-up formulas 100+/-33 and soy-based f ormulas 34+/-9 mg sialic acid/l, respectively. Conclusions: Formula-fe d infants obtain less than 20% of the amount of sialic acid supplied i f breast-fed. A sufficient sialic acid supply may be essential in very -low-birth-weight infants and neonates at risk for the normal developm ent of brain function.