Effect of Dietary Fats and Vitamin E on Oxidative Denaturation of Serum Low Density Lipoproteins. ∗

Summary

The stability or lability of serum low density lipoproteins appeared to be greatly affected by dietary fat and by the presence or absence of vit. E. The low density lipoproteins isolated from the serum of chicks which had been fed corn oil stripped of vit. E under high vacuum were less stable in vitro toward oxidative denaturation catalyzed by hemin than the lipoproteins obtained from the serum of chicks fed hydrogenated coconut oil. Although a dietary source of tocopherol partially prevented the oxidative denaturation of serum low density lipoproteins in chick serum, a decrease in the content of unsaturated dietary fat prevented more effectively the oxidative denaturation of serum low density lipoproteins. The percentage of linoleic and C₂₀ tetraenoic acids in the lipid moiety of the low density lipoproteins as determined by gas chromatography of the methyl esters was shown to be dependent on the percentage of linoleic acid in the dietary fat and was shown to be the most important factor which influenced the stability of the low density lipoproteins. Dietary fats rich in linoleic acid, therefore, should be stabilized with a sufficient amount of vit. E in order to prevent possible in vivo peroxidation of serum and tissue lipoproteins.