Postnatal changes in plasma chain-breaking antioxidants in healthy preterm infants fed formula and/or human milk.

Concentrations of chain-breaking antioxidants were studied in the first 6 postnatal weeks in 29 healthy preterm infants (gestational age 30-35 wk). Vitamin C, uric acid, and sulfhydryl groups declined, whereas vitamin E rose and bilirubin followed its typical biphasic postnatal course. The influence of these changes on the plasma peroxyl radical trapping capacity was assessed in vitro (TRAP assay). The trapping capacity decreased postnatally and this appeared to be related to the coincident fall in uric acid concentrations. Results did not differ between babies fed with only preterm formula (n = 12) and those fed predominantly with human milk (n = 6), except for higher bilirubin and TRAP values in the breast-fed infants. There are major postnatal changes in the concentrations of the plasma chain-breaking antioxidants and this may influence the susceptibility of the preterm baby to oxygen toxicity.