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 d6-RRR-alpha and d2-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 h 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 F2alpha-isoprostanes were approximately 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.
Bruno
Richard S
RS
Linus Pauling Institute, 571 Weniger Hall, Oregon State University, Corvallis, OR 97331, USA.
Leonard
Scott W
SW
Atkinson
Jeffery
J
Montine
Thomas J
TJ
Ramakrishnan
Rajasekhar
R
Bray
Tammy M
TM
Traber
Maret G
MG
D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001682:Biological Availability; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D028421:Isoprostanes / Q000378:metabolism; D008297:Male; D018384:Oxidative Stress; D010919:Placebos; D012907:Smoking; D014811:Vitamin E Deficiency; D024502:alpha-Tocopherol / Q000097:blood; D024504:gamma-Tocopherol / Q000097:blood
D000975:Antioxidants; D028421:Isoprostanes; D010919:Placebos; D024504:gamma-Tocopherol; D024502:alpha-Tocopherol; D001205:Ascorbic Acid