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

« 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, alpha- and gamma-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 P-carotene concentrations than did nonsmokers (0.15, 0.17, and 0.24 mumol/L, respectively) and significantly higher gamma-tocopherol concentrations (7.8, 7.8, and 6.5 mumol/L, respectively). Smokers had significantly lower plasma ascorbic acid and beta-cryptoxanthin concentrations than did nonsmokers and passive smokers (ascorbic acid: 43.6, 54.5, and 54.6 mumol/L, respectively; beta-cryptoxanthin: 0.12, 0.16, and 0.16 mumol/L, respectively) and significantly lower concentrations of lutein and zeaxanthin than did nonsmokers (0.33 compared with 0.41 mumol/L). The P values for all the differences described above were < 0.05. No significant differences in plasma concentrations of a-tocopherol, a-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 ?-tocopherol concentrations were significantly higher in smokers and passive smokers than in nonsmokers."