Intake of supplemental and total fiber and risk of colorectal adenoma recurrence in the wheat bran fiber trial

Abstract

The Wheat Bran Fiber (WBF) trial was a double-blind Phase III clinical trial in which participants were randomized to a cereal fiber supplement of either 13.5 or 2.0 g/day. No protective effect for adenoma recurrence was observed for those randomized to the high-fiber group as compared with those in the low-fiber group. However, the high-fiber group had significantly lower adherence to the supplement as assessed by cereal box counts. The aim of this study was to determine whether reported supplemental and total fiber intake affected colorectal adenoma recurrence in the WBF trial population, regardless of treatment group assignment. A total of 1208 participants who completed the WBF trial had a colonoscopy before the date of the last cereal box count and/or at least one colonoscopy within 90 days after it and, thus, were eligible for the current analyses. Statistical analyses were done using multivariate logistic regression models that included potentially confounding variables. Compared with individuals consuming less than 1.8 g/day of supplemental fiber, the adjusted odds ratio (95% confidence interval) for adenoma recurrence for those consuming greater than 11.0 g/day was 0.94 (0.66-1.33). The odds ratio (95% confidence interval) for participants whose total fiber intake was greater than 30.3 g/day was 0.98 (0.68-1.42) compared with those whose intake was less than 17.9 g/day. The results of this study show that neither fiber intake from a wheat bran supplement nor total fiber intake affects the recurrence of colorectal adenomas, thus lending further evidence to the body of literature indicating that consumption of a high-fiber diet, especially one rich in cereal fiber, does not reduce the risk of colorectal adenoma recurrence.