Copper deficiency does not affect conversion of β-carotene to vitamin A in rats

Abstract

The central cleavage of β-carotene to vitamin A purportedly involves a dioxygenase that may be copper dependent. Therefore, the purpose of this study was to determine the effect of copper (Cu) deficiency on the conversion of β-carotene to vitamin A as measured by total liver retinol. Weanling male rats, pre-depleted of vitamin A, were divided into three groups of 12: I) Cu and vitamin A deficient; II) Cu adequate and vitamin A deficient; pair-fed to group I; III) Cu adequate and vitamin A deficient, fed ad libitum. After four weeks, six animals of each group were killed and hepatic vitamin A determined for baseline (depleted) levels. β-carotene (13.4 mg/kg) was then added to the diets, and after two weeks the rats were killed. Cu deficiency was verified by tissue analyses and by decreased activity of Cu dependent superoxide dismutase. Total liver vitamin A increased similarly in all three groups, ranging from 73–79 μg. Large variations among animals within each group suggests a marked variability in utilization of β-carotene. The results indicate that Cu deficiency does not affect the conversion of β-carotene to vitamin A in the rat.