Effect of a single oral dose of antioxidant mixture (vitamin E, carotenoids) on the formation of cholesterol oxidation products after ex vivo LDL oxidation in humans.

During oxidation of LDL not only polyunsaturated fatty acids and apolipoproteins but also cholesterol is affected. To test the preventive effect of vitamin E and carotenoids against metal ion-induced oxidative modification of the cholesterol moiety, LDL of five females (age 25-30 years) were enriched by single oral supplementation with a mixture of alpha-tocopherol, beta-carotene, lycopene, canthaxanthin, and lutein. LDL was isolated from blood samples before as well as 10 and 24 hours after supplement intake. In the 10 and 24 hours samples, total concentration of the supplemented antioxidants increased significantly to 127% and 125% of the initial value, respectively. As a consequence, the lag phase until beginning of oxidative modification of fatty acids--measured in terms of lag phase time till diene production--significantly increased by 13% (10 h and 24 h). After stopping the oxidation process in all LDL samples (0 h, 10 h, 24 h) of one person when the maximal absorbance value of diene production in the 10 h sample was reached, a statistically significant reduction in the formation of cholesterol oxidation products (COP) could be measured. In the average, 10 h and 24 h after supplementation the COP concentration reached 84% and 86% of the 0 h-value, respectively. Except for 7 beta-hydroxycholesterol, all COP measured decreased by 10-20%. The results of the in vitro-model demonstrate that an antioxidant enrichment of LDL has the potential to protect also cholesterol (besides unsaturated fatty acids) against oxidative modification.