Design and baseline characteristics of study participants in the Wheat Bran Fiber trial.

The Wheat Bran Fiber (WBF) trial is a Phase III clinical trial designed to assess the effect of a WBF intervention for 3 years on the recurrence of adenomatous polyps. Men and women, 40-80 years of age, who had removal of one or more colorectal adenoma(s) 3 mm or larger within 3 months prior to study entry were recruited from three sites in the Phoenix metropolitan area. After meeting eligibility criteria, 1509 individuals entered a 6-week run-in period, consisting of a low WBF (2 g/day) intervention. Participants (n = 1429) successfully completed this phase and were randomized to a high (13.5 g/day) or low (2 g/day) WBF intervention. Various data and specimens were collected at baseline and throughout the intervention phase, which included dietary intake, physical activity, other risk factor information, blood specimens, rectal biopsies, and polyp tissues. The study design called for a colonoscopy at approximately 1 year after the qualifying colonoscopy; thus, the period between the first year and the final colonoscopy will be used to assess the effect of the intervention, which is expected to be completed in the latter part of 1998.