SIALIC-ACID CONTENT OF INFANT SALIVA - COMPARISON OF BREAST-FED WITH FORMULA-FED INFANTS

Sialic acid is found in especially high concentrations in brain gangli osides, and supplementary sialic acid is associated with increased lea rning behaviour in animals. It was hypothesised that breast fed infant s may have higher concentrations of sialic acid in body fluids and tis sues because human milk is a rich source of sialylated oligosaccharide s, while formulas contain very Little. The aim therefore was to compar e the sialic acid content of saliva collected from full term infants w ho were either solely breast fed or formula fed until weaning at 3-5 m onths of age. Thirty three infants, 18 breast fed and 15 formula fed, were studied at a mean (SD) age of 5 (2) months. The breast fed infant s, when compared with formula fed infants, were found to have almost t wo times more free sialic acid in saliva (mean (SE) 16.0 (2.7) v 8.2 ( 2.1) mg/l, p < 0.036) and nearly 50% more total sialic acid (47.3 (3.9 ) v 32.2 (4.4) mg/l, p < 0.014). The findings provide a preliminary in dication that an exogenous source of sialic acids derived from human m illi may contribute to higher concentrations of sialic acid in body fl uids. There are important implications for the formulation of human mi lk substitutes.