Abstract
The content of N-acetylneuraminic acid (NeuAc) in serum, urine and feces from breast-fed and formula-fed infants at 2-7 days after delivery was determined. The serum content of NeuAc in breast-fed infants was 41.2±8.58mg/dl and that in formula-fed infants was 37.0±5.45mg/dl, the latter being significantly lower (p<0.05). The ratio of NeuAc to creatinine in urine of breast-fed infants was 0.390±0.079 and that of formula-fed infants was 0.294±0.081 (p<0.05). The content of NeuAc in feces of breast-fed infants was 4.59±2.10mg/g fresh feces, and that in formula-fed infants was 2.36±1.00mg/g fresh feces. The amount of NeuAc excreted into urine and feces was 18.6mg/day and 45.9mg/day in breast-fed infants, and 14.0mg/day and 23.6mg/day in formula-fed infants. High-performance thin-layer chromatography revealed little 6′-sialyllactose in urine and feces of formula-fed infants. These differences may be because human milk contains more NeuAc than infant formula.
