Oxidative stress in smokers supplemented with vitamin C

The ability of vitamin C supplement to influence lipid peroxidation and pulmonary function tests in healthy smokers was investigated. In this randomized double blind controlled trial, 56 smokers (S) received either 500 mg of vitamin C (C) or placebo (P) daily for 4 weeks. All completed the trial. Both groups were comparable and the number of cigarettes smoked were C: 14.2 +/- 1.8 and P: 18.3 +/- 2.0 pack-years. Plasma vitamin C concentrations increased significantly (p < 0.005) only in the group supplemented with vitamin C. Lipid peroxidation measured by breath pentane output (BPO) (C: 7.5 +/- 1.4 vs P: 7.0 +/- 1.3 pmol.kg(-1).min(-1)) and plasma HPLC-separated malondialdehyde (MDA) (C: 0.58 +/- 0.05 vs P: 0.47 +/- 0.05 nmol.ml(-1)) were not significantly different between the 2 groups at baseline and did not change after four weeks of vitamin C supplementation (BPO: C: 5.3 +/- 0.9 vs P: 5.5 +/- 0.9 pmol.kg(-1).min(-1); HPLC-MDA: C: 0.50 +/- 0.07 vs P: 0.42 +/- 0.07 nmol.ml(-1)). No changes were detected in pulmonary function tests eve in heavy smokers. Therefore 4 week supplementation with 500 mg of vitamin C did not change lipid peroxidation indices and had no effect on pulmonary function tests.