Faster plasma vitamin E disappearance in smokers is normalized by vitamin C supplementation

Vitamin E disappearance is accelerated in cigarette smokers due to their increased oxidative stress and is inversely correlated with plasma vitamin C concentrations. Therefore, we hypothesized that ascorbic acid supplementation (500 mg, twice daily; 2 weeks) Would normalize smokers' plasma alpha- and gamma-tocopherol disappearance rates and conducted a double-blind, placebo-controlled, randomized crossover investigation in smokers (n = 11) and nonsmokers (n = 13) given a single dose of deuterium-labeled alpha- and gamma-tocopherols (50 mg each d(6)-kRR-alpha and d(2)-RRR-gamma-tocopheryl acetate). During the placebo trial, smokers, compared with nonsmokers, had significantly (P < 0.05) greater alpha- and gamma-tocopherol fractional disappearance rates and shorter half-lives. Ascorbic acid supplementation doubled (P < 0.0001) plasma ascorbic acid concentrations in both groups and attenuated smokers', but not nonsmokers', plasma alpha- and gamma-tocopherol (P < 0.05) fractional disappearance rates by 25% and 45%, respectively. Likewise, smokers' plasma deuterium-labeled alpha- and gamma-tocopherol concentrations were significantly higher (P < 0.05) at 72 It during ascorbic acid supplementation compared with placebo. Ascorbic acid supplementation did not significantly change (P > 0.05) time of maximal or maximal-labeled alpha- and gamma-tocopherol concentrations. Smokers' plasma F-2 alpha-isoprostanes were similar to 26% higher than nonsmokers (P > 0.05) and were not affected by ascorbic acid Supplementation in either group (P > 0.05). In summary, cigarette smoking increased plasma alpha- and gamma-tocopherol fractional disappearance rates, suggesting that the oxidative stress from smoking oxidizes tocopherols and that plasma ascorbic acid reduces alpha- and gamma-tocopheroxyl radicals to nonoxidized forms, thereby decreasing vitamin E disappearance in humans. (c) 2005 Elsevier Inc. All rights reserved.