Zinc deficiency and vitamin E status in rats fed olive oil or linseed oil

SUMMARY: The present study was carried out to investigate the effect of zinc deficiency on the vitamin E status in rats fed diets containing either olive oil or linseed oil, using a bifactorial experimental design. To ensure an adequate food intake, all the rats were force-fed by gastric tube. The zinc concentrations of the zinc-deficient diets were 0.5 mg/kg; zinc-adequate diets were supplemented with 45 mg Zn/kg. All the diets were adjusted to an identical vitamin E activity of 75 IU per kg of diet by supplementation with all-rac-α-tocopherol acetate. Parameters used to assess the vitamin E status were concentrations of tocopherols in plasma, heart and liver tissues and liver microsomes. Feeding the zinc-deficient diets markedly lowered body weight gain, plasma zinc concentration and activity of alkaline phosphatase in plasma. In contrast, tocopherol concentrations in liver and heart tissues and in liver microsomes were not influenced by zinc deficiency, regardless of the type of fat. Zinc-deficient rats fed linseed oil had higher concentrations of tocopherols in plasma than zinc-adequate rats fed linseed oil. However, tocopherol concentrations in plasma were significantly correlated with plasma lipid concentrations, and increased concentrations of tocopherols in zinc-deficient rats fed linseed oil were due to increased concentrations of plasma lipids in those rats. Tocopherol concentrations related to concentrations of plasma total lipids were not different between zinc-deficient and zinc-adequate rats fed both types of fat. Those results demonstrate that zinc deficiency does not affect the vitamin E status of rats. The concentration of malondialdehyde in liver microsomes which is a product of lipid peroxidation was also not influenced by zinc-deficiency. The dietary fat also did not influence the concentrations of total tocopherols in liver and heart tissues and liver microsomes. In contrast, the concentration of total tocopherols in plasma was higher in the rats fed olive oil than in the rats fed linseed oil. However, this effect was due to higher plasma lipid concentrations in the rats fed olive oil, and the tocopherol concentrations, expressed per mg of plasma total lipids, were even higher in the rats fed linseed oil.