Effect of a cereal fiber intervention on nutrient intake and adenoma recurrence in the Wheat Bran Fiber trial

Abstract

The Wheat Bran Fiber (WBF) trial was a double-blind, placebo-controlled intervention trial in which participants were randomized to receive a cereal fiber supplement of either 2.0 or 13.5 g/day to determine whether the high-fiber supplement could decrease the risk of recurrent colorectal adenomas. No effect of the supplement was observed. However, there are several issues in the WBF trial that remain to be explored, including whether there were non-supplemental dietary changes throughout the course of the study, and whether baseline fiber intake or the amount of fiber consumed by participants during the trial were associated with adenoma recurrence. With regard to changes in nutrient intake, no significant differences were found between the high-fiber and low-fiber groups at any of the three time points. Therefore, data from the two treatment groups were combined to assess longitudinal change during the study. Participants significantly decreased their fat intake during the trial, but the intake of most micronutrients was increased. With regard to food groups, the number of servings of fruits, vegetables, and dairy products did not change appreciably, while servings from the fat and meat groups were significantly decreased. The intake of cereals, breads and crackers increased significantly, possibly due to the addition of the cereal supplement to the diet. Furthermore, it is likely that the increase in micronutrient intake can be attributed to the consumption of the study supplement. The next issue was whether baseline fiber intake was associated with risk of adenoma recurrence. No association was found between the amount of fiber consumed at baseline and adenoma recurrence, nor did baseline fiber intake modify the effect of treatment group. Finally, it was important to determine whether the amount of fiber consumed during the WBF trial, regardless of treatment group, was associated with adenoma recurrence. There were no significant associations between amount of.