Brain ganglioside and glycoprotein sialic acid in infants fed human milk vs infant formula

Background: The concentration of sialic acid in brain gangliosides
and glycoproteins has been linked to learning ability in
animal studies. Human milk is a rich source of sialic acid–containing
oligosaccharides and is a potential source of exogenous
sialic acid.
Objective: The aim of the study was to compare the sialic acid
concentration in the brain frontal cortex of breastfed and formulafed
infants.
Design: Twenty-five samples of frontal cortex derived from infants
who died of sudden infant death syndrome were analyzed.
Twelve infants were breastfed, 10 infants were formula-fed, and 1
infant was mixed-fed; the feeding status of the remaining 2 infants
was unknown. Ganglioside-bound and protein-bound sialic acid
were determined by HPLC. Ganglioside ceramide fatty acids were
also analyzed to determine the relation between sialic acid and
long-chain polyunsaturated fatty acids.
Results: After adjustment for sex with age at death as a covariate,
ganglioside-bound and protein-bound sialic acid concentrations
were 32% and 22% higher, respectively, in the frontal cortex gray
matter of breastfed infants than in that of formula-fed infants (P
0.01). Protein-bound sialic acid increased with age in both groups
(P 0.02). In breastfed but not in formula-fed infants, ganglioside-
bound sialic acid correlated significantly with ganglioside
ceramide docosahexaenoic acid and total n3 fatty acids.
Conclusions: Higher brain ganglioside and glycoprotein sialic
acid concentrations in infants fed human milk suggests increased
synaptogenesis and differences in neurodevelopment.