[Importance of breast-feeding in antioxidant defence]

We investigated the importance of two enzymes (superoxide dismutase--SOD and glutathione peroxidase--GSH-Px) in the antioxidant defence of newborns and analysed their activity in: human colostrum and milk (from 63 mothers, after normal delivery, without complications or signs of infection), gastric fluid (from 10 breast-fed newborns, 7-28 days after birth; and from 15 artificially-fed newborns, with no signs of infection, 7-28 days after birth), and plasma (from 10 newborns, 1-28 days old, with no signs of infection, and 10 newborns, 1-28 days old, with signs of neonatal sepsis). The results of the study showed that there was statistically significant increased activity of SOD (p<0.001) in colostrum compared to mature milk. There was no statistically important difference in the activity of GSH-Px between those two samples. The activity of SOD in the gastric fluid of the artificially-fed newborns was statistically significantly lower than in the breast-fed newborns (p<0.001). The same results were found for mature mother's milk. We discovered a significant increase of SOD plasma activity in the newborns with sepsis, compared to the breast-fed newborns, with no signs of infection. The negative correlation between the activities of SOD and GSH-Px in the gastric fluid samples of the breast-fed and the artificially-fed newborns and the newborns with sepsis, showed that the activities of both enzymes were important for adequate antioxidant defence during the neonatal period. Breast-feeding with both colostrum and mature human milk is probably very important for adequate antioxidant defence in newborns.