Flow Diagram of the progress through the phases of the study. Assuming a drop-out rate of 5% of patients for the control colonoscopy, 1267 randomized patients per arm will be required, resulting in randomization of 2534 patients after the run-in period. 1203 patients per arm are expected to be available for the ITT analysis undergoing control colonoscopy after three years. A drop-out rate of 20% is assumed for regular capsule intake. Thus, 1014 patients will be evaluable for the per-protocol analysis of the green tea effect.