Objective: To determine the concentration of secretory immunoglobulin A (SIgA) in human milk at 1, 2, 3 and 4 months after delivery and in infants' feces in the same period and find out the effect of milk on the content of SIgA in infants' intestine.
Methods: 20 women and 12 breast feeding infants and 13 formula feeding infants were studied, and milk and infants' feces were collected at 1, 2, 3 and 4 months after delivery, respectively. The concentrations of SIgA in milk and feces were determined by radioimmunoassay.
Results: No apparent changes in the concentration of SIgA were found in human milk and feces from breast feeding and formula feeding infants at 1-4 months after delivery, but the concentration of fecal SIgA in breast feeding infants was significantly higher than that in the formula feeding infants, during the first 4 months after birth.
Conclusions: Human milk can provide a large amount of SIgA for infants. We conclude from these data that human milk is beneficial in protecting the immunological function of infants digestive tract.