Does vitamin C supplementation influence the levels of circulating oxidized LDL, sICAM-1, sVCAM-1 and vWF-antigen in healthy male smokers?

Objective: To examine the effects of vitamin C supplementation on the concentration of oxidation markers, in particular, circulating oxidized LDL ( OxLDL) and on endothelial activation markers. Design: Randomized double-blind, placebo-controlled crossover trial. Setting: Belgian population of the city of Leuven. Subjects: A total of 34 healthy male smokers aged 26 - 73 y. Intervention: Smokers were randomly assigned to receive either vitamin C (250 mg twice daily) or placebo capsules, each to be taken for 4 weeks. After a 1-week washout period, participants then crossed over to the alternative capsules for further 4 weeks. Mean outcome measures: Markers of oxidation (bilirubin, uric acid, alpha-tocopherol, retinol, malondialdehyde, circulating Oxidized LDL ( OxLDL)) and markers of endothelial activation (sICAM-1, sVCAM-1, vWF-antigen) were analysed. Results: Plasma ascorbate concentrations significantly increased from 46.6 +/- 17.6 to 70.1 +/- 21.2 mumol/l after a 4-week treatment with 500 mg vitamin C per day. The other plasma antioxidants concentrations, including bilirubin, uric acid, alpha-tocopherol and retinol, were similar in both treatment periods. Vitamin C did not change plasma malondialdehyde and circulating OxLDL compared with placebo (vitamin C 0.73 +/- 0.25 mg/dl OxLDL; placebo 0.72 +/- 0.21 mg/dl OxLDL). After vitamin C supplementation, neither sICAM-1 and sVCAM-1 levels nor the concentration of vWF-antigen significantly differed from placebo condition. Conclusions: Oral supplementation of vitamin C is not associated with changes in markers of oxidation or endothelial activation in healthy male smokers. Sponsorship: The Unilever Chair in Nutritional Epidemiology, University of Leuven, Belgium.