Faster plasma vitamin E disappearance in smokers is normalized by vitamin C supplementation
| Autor: | Thomas J. Montine, Rajasekhar Ramakrishnan, Jeffery Atkinson, Tammy M. Bray, Richard S. Bruno, Scott W. Leonard, Maret G. Traber |
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| Rok vydání: | 2006 |
| Předmět: |
Adult
Male medicine.medical_specialty medicine.medical_treatment alpha-Tocopherol Administration Oral Biological Availability Alpha (ethology) Ascorbic Acid Isoprostanes Placebo medicine.disease_cause Biochemistry Antioxidants Placebos Double-Blind Method Physiology (medical) Internal medicine medicine Humans Vitamin E Deficiency Cross-Over Studies gamma-Tocopherol Vitamin C Chemistry Vitamin E Smoking Ascorbic acid Crossover study Oxidative Stress Endocrinology Dietary Supplements Female Vitamin E deficiency Oxidative stress |
| Zdroj: | Free Radical Biology and Medicine. 40:689-697 |
| ISSN: | 0891-5849 |
| Popis: | 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 d6-RRR-alpha and d2-RRR-gamma-tocopheryl acetate). During the placebo trial, smokers, compared with nonsmokers, had significantly (P0.05) greater alpha- and gamma-tocopherol fractional disappearance rates and shorter half-lives. Ascorbic acid supplementation doubled (P0.0001) plasma ascorbic acid concentrations in both groups and attenuated smokers', but not nonsmokers', plasma alpha- and gamma-tocopherol (P0.05) fractional disappearance rates by 25% and 45%, respectively. Likewise, smokers' plasma deuterium-labeled alpha- and gamma-tocopherol concentrations were significantly higher (P0.05) at 72 h during ascorbic acid supplementation compared with placebo. Ascorbic acid supplementation did not significantly change (P0.05) time of maximal or maximal-labeled alpha- and gamma-tocopherol concentrations. Smokers' plasma F2alpha-isoprostanes were approximately 26% higher than nonsmokers (P0.05) and were not affected by ascorbic acid supplementation in either group (P0.05). 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. |
| Databáze: | OpenAIRE |
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