Long-term effects of smoking on serum concentrations of oxidative stress biomarkers: Results of a large, population-based cohort study.

INTRODUCTION

Cross-sectional studies have consistently shown an association between current smoking and oxidative stress biomarkers. However, no longitudinal studies have been performed so far.

METHODS

The oxidative stress biomarkers "total thiol groups of serum proteins" (TTP), and "derivatives of reactive oxygen metabolites" (D-ROM) were measured in serum samples of 3835 participants of a population-based, German cohort study of older adults (age: 60-84 years) with repeated measurements for 2834 participants three years later. Multivariable linear regression models were applied and β-coefficients with 95% confidence intervals were obtained.

RESULTS

In both cross-sectional and longitudinal analysis, current smoking was statistically significantly associated with increased D-ROM levels, and a dose-response relationship between the amount of daily tobacco consumption and the D-ROM concentrations was observed that plateaued at ≥15 g of tobacco consumption per day. Former smoking was also associated with D-ROM levels. Only former smokers who quitted smoking more than 10 years ago had no increased D-ROM levels compared to never smokers. There was neither a cross-sectional nor longitudinal association between any of the smoking variables and TTP levels.

CONCLUSION

This large population-based cohort of older German adults suggests that smoking has long-term effects on the oxidative stress burden. The further increasing D-ROM levels of current smokers at an older age and the observation that it may take more than 10 years until the redox balance is restored are solid arguments for quitting smoking as soon as possible at any age.