The White Diet is preferred, better tolerated, and non-inferior to a clear-fluid diet for bowel preparation: A randomized controlled trial

Background and Aim: Dietary restrictions contribute to the unpleasantness of bowel preparation for colonoscopy. We compare the effectiveness and tolerability of a low residue diet of white-colored foods ("White Diet") with a clear-fluid diet the day prior to colonoscopy in an endoscopist-blinded randomized non-inferiority trial. Methods: Adults undergoing outpatient colonoscopy were randomized with stratification by procedure timing to a White Diet or clear-fluid diet. All received a 2-L polyethylene glycol lavage solution with ascorbate, sodium sulfate, and electrolytes, the day-before for morning and as a split-dose for afternoon procedures. The primary end-point was successful bowel preparation (A or B on the Harefield Cleansing Scale). Regimen tolerance/acceptance was assessed by questionnaire. An intention-to-treat analysis with a predefined non-inferiority margin of 15% was used to compare efficacy. Results: A total of 226 patients (average age 52years, 51% male) were randomized (111 clear diet, 115 White Diet). Bowel preparation was successful in 91% on the clear-fluid diet vs 84.4% on the White Diet, difference being -6.6% (lower one sided 95% CI -13.8%), with no difference according to diet. The split-dose regimen (in 55%) had a higher success rate than day-before regimen (96% vs 80%, p<0.001). The White Diet was preferred with less hunger and interference with daily activities (p<0.001). Procedural/withdrawal time and polyp/adenoma detection were similar between groups. Conclusions: The White Diet was preferred and better tolerated by patients without detriment to the success of bowel preparation or colonoscopy performance, especially with the split-dose regimen.