Gender difference in systemic oxidative stress and antioxidant capacity in current and former heavy smokers

Background: Several studies suggested that women may be more susceptible to oxidative damage induced by cigarette smoking, but the role of smoking status and antioxidant capacity in gender difference in susceptibility to oxidative damage has not been well studied. Methods: We conducted a cross-sectional analysis of the baseline data from 146 current and former heavy smokers enrolled in a chemoprevention trial to determine the gender difference in oxidative damage and antioxidant capacity. Oxidative DNA and lipid damage were assessed by urinary 8-hydroxy-2′-deoxyguanosine (8OHdG) and 8-isoprostaglandin F _2α (8-iso-PGF_2α), respectively. The erythrocyte antioxidant enzymes and serum fat-soluble antioxidants were measured to assess antioxidant capacity. Results: Female smokers had significantly greater levels of 8OHdG and 8-iso-PGF_2α than males but the gender difference was only significant in current smokers. No gender difference was noted in erythrocyte antioxidant enzymes, although female current smokers had significantly lower or a trend for lower antioxidant enzymes. Female smokers had higher serum β-carotene than males. Biomarkers of oxidative damage did not correlate significantly with the antioxidant enzymes. Urinary 8OHdG did not correlate significantly with fat-soluble antioxidants. Inverse correlations were observed between urinary 8-iso-PGF_2α and several serum carotenoids. Conclusion: Female current smokers have a greater extent of oxidative damage despite having higher serum levels of fat-soluble antioxidants. Lower erythrocyte antioxidant enzymes in female current smokers may contribute to the greater extent of oxidative damage. Impact: The study may help identify appropriate high-risk populations for interventions that attenuate oxidative damage and appropriate biomarkers for clinical studies in smokers.