CONCENTRATIONS OF LIPIDS IN PLASMA AND LIPOPROTEINS AND OXIDATIVE SUSCEPTIBILITY OF LOW-DENSITY LIPOPROTEINS IN ZINC-DEFICIENT RATS FED LINSEED OIL OR OLIVE OIL

The present study was performed to investigate the effect of zinc defi ciency on concentrations of lipids in plasma and lipoproteins and the susceptibility of low-density lipoproteins (LDL) to lipid peroxidation in rats fed diets containing either linseed oil or olive oil as dieta ry fat, using a bifactorial experimental design. To ensure an adequate food intake, all rite rats were force-fed by gastric tube. The dietar y fat had a stronger effect on those parameters than the zinc supply. Rats fed linseed oil had lower concentrations of cholesterol, triglyce rides, and phospholipids in plasma and lipoproteins but a higher susce ptibility of LDL to lipid peroxidation than rats fed alive oil. The ef fect of zinc deficiency on those parameters were modified by the dieta ry fat Zinc-deficient mts fed linseed oil had increased concentrations of total lipids, cholesterol, and phospholipids in plasma as well as in low- and high-density lipoproteins and an increased susceptibility of LDL to copper-induced lipid peroxidation compared to zinc-adequate rats fed linseed oil. The increased susceptibility of LDL in those rat s might be attributable to increased levels of arachidonic acid and ei cosapentaenoic acid in LDL. In contrast, in zinc-deficient rats fed ol ive oil, concentrations of lipids in plasma and lipoproteins were only slightly changed and the susceptibility of LDL to copper-induced lipi d peroxidation was reduced compared to zinc-adequate rats fed olive oi l. Tocopherol concentrations in plasma, expressed per mol lipid, were not influenced by zinc deficiency in the rats fed both types of fat. T herefore, a changed vitamin E status might not be involved in the effe cts of zinc deficiency on the susceptibility of LDL. In conclusion the study shows that the effects of zinc deficiency on the concentrations of plasma lipids and the susceptibility of LDL to lipid peroxidation depend on the type of fat. Therefore, the type of dietary fat must be given attention in the investigation of the effects of zinc deficiency on parameters of lipid metabolism. (C) Elsevier Science Inc. 1997.