Smoking and exposure to environmental tobacco smoke decrease some plasma antioxidants and increase γ-tocopherol in vivo after adjustment for dietary antioxidant intakes

Abstract

Background: Free radicals in cigarette smoke may cause oxidative damage to macromolecules, contributing to cardiovascular diseases and cancer. Decreased plasma antioxidant concentrations may indicate cigarette smoke-related oxidative stress. Objective: We compared the effects on plasma antioxidant concentrations in cotinine-confirmed active and passive smokers with those in nonsmokers, independent of differences in dietary intakes and other covariates. Design: Plasma samples from 83 smokers, 40 passive smokers, and 36 nonsmokers were analyzed for total ascorbic acid, α- and γ-tocopherols, 5 carotenoids, retinol, and cotinine. Groups were compared by using analysis of variance with adjustment for sex, age, race, body mass index, alcohol intake, triacylglycerol concentration, fruit and vegetable intakes, and dietary antioxidants. Results: After adjustment for dietary antioxidant intakes and other covariates, smokers and passive smokers had significantly lower plasma β-carotene concentrations than did nonsmokers (0.15, 0.17, and 0.24 μmol/L, respectively) and significantly higher γ-tocopherol concentrations (7.8, 7.8, and 6.5 μmol/L, respectively). Smokers had significantly lower plasma ascorbic acid and β-cryptoxanthin concentrations than did nonsmokers and passive smokers (ascorbic acid: 43.6, 54.5, and 54.6 μmol/L, respectively; β-cryptoxanthin: 0.12, 0.16, and 0.16 μmol/L, respectively) and significantly lower concentrations of lutein and zeaxanthin than did nonsmokers (0.33 compared with 0.41 μmol/L). The P values for all the differences described above were < 0.05. No significant differences in plasma concentrations of α-tocopherol, α-carotene, total carotenoids, lycopene, or retinol were observed. Conclusions: These results indicate that cigarette smokers and nonsmokers exposed to cigarette smoke have a significantly lower plasma antioxidant status than do unexposed nonsmokers, independent of differences in dietary antioxidant intakes. Further research is required to explain why plasma γ-tocopherol concentrations were significantly higher in smokers and passive smokers than in nonsmokers.