Effect of age, smoking and other lifestyle factors on urinary 7-methylguanine and 8-hydroxydeoxyguanosine.

Urinary 8-hydroxydeoxyguanosine (8-OH-dG) and 7-methylguanine (m⁷Gua) were measured by a column-switching high performance liquid chromatography method as markers of oxidative and methylating DNA damage, respectively. We investigated the associations between urinary 8-OH-dG or m⁷Gua and various lifestyle and demographic factors, such as age and sex. The urinary 8-OH-dG excretion level was positively correlated with cigarette smoking, but inversely correlated with fruit consumption, physical activity and total energy consumed per day. A multiple regression analysis revealed that daily physical activity and healthy meal combinations decreased the urinary 8-OH-dG level, whereas alcohol consumption increased it. In terms of the urinary m⁷Gua measurement, cigarette smoking, age and consumption of meat, fish, egg, soybean, etc. were positively correlated with the urinary m⁷Gua level, whereas body weight, BMI, physical activity, and dietary index score, which indicates good nutritional balance, were negatively correlated with the amount of m⁷Gua. Based on a multiple regression analysis, cigarette smoking and age correlated with the m⁷Gua level, while high BMI and healthy meal combinations have significant reducing effects on m⁷Gua level. Therefore, the urinary m⁷Gua level is considered to be a useful marker of DNA methylation, not only from smoking, but also from aging and unhealthy dietary habits. ( Cancer Sci 2009; 100: 715–721) [ABSTRACT FROM AUTHOR]