Dietary Supplementation With Orange and Carrot Juice in Cigarette Smokers Lowers Oxidation Products in Copper–Oxidized Low–Density Lipoproteins

Abstract

Objective Our objective was to evaluate the effect of daily supplementation with foods high in vitamin C and beta carotene on plasma vitamin levels and oxidation of low–density lipoprotein (LDL) in cigarette smokers. Subjects Fifteen normolipidemic male cigarette smokers who did not usually take vitamin supplements were recruited into the study. Interventions Throughout the study, subjects consumed a diet rich in polyunsaturated fatty acids, which provided 36% of energy as fat: 18% from meat, dairy products, vegetable oils, and fat spreads and 18% from walnuts (68 g/day). Subjects consumed a vitamin–free drink daily for 3 weeks; then for 3 weeks they consumed daily supplements of orange juice (145 mg vitamin C) and carrot juice (16 mg beta carotene). Results Vitamin–rich food supplements raised plasma levels of ascorbic acid (1.6–fold; P<.01) and beta carotene (2.6–fold; P<.01). Malondialdehyde, one end product of oxidation, was lower in copper–oxidized LDL after vitamin supplementation (mean±standard error=65.7±2.0 and 57.5±2.9 μmol/g LDL protein before and after supplementation, respectively; P<.01). Rate of LDL oxidation and lag time before the onset of LDL oxidation were not affected by antioxidant supplementation. Conclusions In habitual cigarette smokers, antioxidant vitamins, which can be feasibly provided from food, partly protected LDL from oxidation despite a diet rich in polyunsaturated fatty acids. J Am Diet Assoc. 1995; 95: 671–675.