A Chemoprevention Trial to Study the Effects of High Tea Consumption on Smoking-Related Oxidative Stress

Our overall goal is to develop a safe and feasible model for the chemoprevention of a wide range of tobacco-related diseases. Our immediate goal, that was addressed over a 5-year study period, is to determine the effects of high tea consumption on biological markers of oxidative stress that mediate lung cancer risk. We completed a 6-month randomized, controlled, double-blinded chemopreventive trial in a group of chronic obstructive pulmonary disease (COPD) subjects who are being randomized to green or black tea preparations or a control intervention (matching placebo). Levels of 8-hydroxydeoxyguanosine and 8-F2-isoprostanes are used to measure DNA and lipid damage respectively. Changes in biomarkers of oxidative damage were measured in urine and blood. The study protocol was approved by all parties in September 2003. Recruitment and screening of participants for eligibility criteria started in October 2003. Total recruitment was completed in December 2007. A total of 158 participants (86 females and 72 males) completed the study. All laboratory analyses, data entry, and quality control measures were completed. Our preliminary data show that although women have a significant lower pack/year smoking history, they have significantly higher DNA damage as measured by urinary 8-OhDG. Female smokers on green tea have a 35% significant decrease in DNA damage and a significant decrease in blood cholesterol and LDL levels. These data confirm our previous findings related to the beneficial effects of green tea on DNA damage among smokers.
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