Possible antioxidant effect of vitamin A supplementation in premature infants

Background: Increased lipid peroxidation caused by oxygen free radicals is thought to be one of the common pathogenetic mechanisms for the so-called oxygen radical diseases of pre-maturity. Since in vitro studies have shown that various forms of vitamin A can exert antioxidant effects that are more potent than those of vitamin E (treatment with which has been ineffective in these diseases), the purpose of this prospective, controlled study was to determine whether administration of supplemental vitamin A to premature infants deficient in this vitamin would have an antioxidant effect in vivo. Methods: Fourteen infants (1181 ± 35 g; gestational age 29 ± 0.04 weeks) with a serum retinol concentration at 7 ± 2 days of age in the deficient range, lower than 0.7 μmol/l (<20 μg/dl), were enrolled in the study. Infants were randomized to receive the standard amount of vitamin A or standard plus supplemental (2.6 μmol/l [2500 IU] orally each day) vitamin A, beginning at 1 week of age. Antioxidant effects of supplementation were assessed by a decrease in lipid peroxidation, quantified by the ethane content of expired air. Results: Three weeks after study enrollment, total dully vitamin A intake in the infants receiving supplements was 4.565 ± 0.236 μmol (4354 ± 225 IU) versus 1.879 ± 0.317 μmol/l (1792 ± 302 IU) in infants receiving standard amounts of the vitamin. In spite of the difference in intake of vitamin A, 3 weeks after study enrollment, serum retinol concentrations did not differ between the infants given supplements and those receiving standard amounts of vitamin A, 0.70 ± 0.21 versus 0.66 ± 0.07 μmol/l (20 ± 6 μg/dl versus 19 ± 2 μg/dl, respectively). In the infants receiving supplemental vitamin A, breath ethane values declined from baseline values. There was an inverse correlation between the number of weeks of supplementation and breath ethane values, whereas there was no significant correlation between the duration of the study and breath ethane values in the infants not given supplements. Conclusions: Our data suggest that supplementation with vitamin A in a small group of vitamin A-deficient preterm infants was associated with an antioxidant effect. Although no immediate clinical benefits were associated with supplementation, the data provide the rationale for future investigations of possible antioxidant effects of (larger amounts) of vitamin A in higher risk premature infants born with subnormal serum retinol concentrations.