Copper, zinc and superoxide dismutase activities in premature infants: a review.

Zinc and copper are quite abundant trace elements and important in many metabolic processes and enzyme systems. Preterm infants whose diet is deficient in copper and/or zinc may suffer anemia, anorexia, skin changes, diarrhea, growth retardation, impaired connective tissue formation, osteoporosis, and impaired cell mediated immunity as well as failure to thrive. The fetus stores 70% of its body reserve of copper and zinc in the last trimester, indicating that the premature infant has low reserves of cooper and zinc at delivery. They may not amass or develop body stores in the same was as does the fetus. Premature infants receiving pasteurized breast milk have a negative zinc balance for at least the first 60 days of life and a negative copper balance for the first 35 days of life. Parental nutrition without copper and zinc supplements result in deficiency conditions. Some oxidation-reduction reactions using oxygen may generate free radicals; with ventilators delivering oxygen directly into the alveoli, generated free radicals may pulmonary oxygen toxicity. This condition is called bronchopulmonary dysplasia (BPD). Preterm infants without hyaline membrane disease are more likely to support hyperopic increase of pulmonary superoxide dismutase (SOD) (a free radical scavenger) activities than those with hyaline membrane disease (e.g., plasma samples, 88.5% vs. 33%). This suggests that preterm infants with the condition do not have a plasma factor needed for pulmonary SOD response. A possible factor is ceruloplasmin. Copper and zinc are important components of both SOD and ceruloplasmin. More research is needed to examine serial levels of copper, zinc, SOD, and ceruloplasmin in newborns to determine whether postnatal levels are linked to associated morbidities. In the event of failure of vitamin E therapy, administration of bovine SOD to premature infants may prevent and reduce the severity of BPD. In developing countries, physicians should prevent BPD and other chronic problems of premature infants by administering antioxidants with copper and zinc.