1. ¹Department of Public Health, Division of Nutritional Epidemiology, University of Leuven, Leuven, Belgium
2. ²Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen, The Netherlands
3. ³Metabolic Research Unit, University of Antwerp, Antwerp, Belgium
4. ⁴Department of Public Health, Division of Youth Health Care, University of Leuven, Leuven, Belgium

Correspondence: EHM Temme, Department of Public Health, Division of Nutritional Epidemiology, Kapucijnenvoer 33, B-3000 Leuven, Belgium. E-mail: Liesbeth.Temme@med.kuleuven.ac.be

Received 22 October 2003; Revised 22 March 2004; Accepted 1 April 2004; Published online 5 May 2004.

Abstract

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, -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 46.617.6 to 70.121.2 mol/l after a 4-week treatment with 500 mg vitamin C per day. The other plasma antioxidants concentrations, including bilirubin, uric acid, -tocopherol and retinol, were similar in both treatment periods. Vitamin C did not change plasma malondialdehyde and circulating OxLDL compared with placebo (vitamin C 0.730.25 mg/dl OxLDL; placebo 0.720.21 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.