Effect of dietary zinc deficiency on vitamin A and alpha-tocopherol metabolism in the rat

Abstract

In order to study the effect of alimentary zinc deficiency on vitamin A and alpha-tocopherol metabolism, weaned, male Sprague-Dawley rats with a mean weight of 48 g were divided into three groups. Zinc depletion animals (n = 7) were provided a half-synthetic, casein-based diet with a zinc concentration of 1.3 ppm; the pair-fed (n = 7) and ad libitum-fed (n = 6) control animals were given a diet containing 96 ppm zinc. After 24 days, the serum zinc level for depletion animals was 80% lower than the level for the two control groups, although the vitamin A, beta-carotine and tocopherol concentrations in deficiency animals and in pair-fed control animals did not differ significantly from one another. In comparison with adlibitum-fed control rats, however, vitamin A and beta-carotine concentrations in depletion and pair-fed animals were elevated. The zinc concentration in livers of deficiency animals was reduced only in comparison to the value for pair-fed control animals, while the vitamin A, beta-carotine and alpha-tocopherol concentrations in livers of zinc-deficient animals were reduced in comparison to the values for both of the control groups. Nevertheless, these changes are less likely a result of zinc deficiency per se, but rather are more likely a result of the lowered feed intake during zinc deficiency and the reduced growth.