Original Article

Effect of Diet Liberalization on Bowel Preparation

Authors: Danny J. Avalos, MD, Daniel A. Sussman, MD, MSPH, Luis F. Lara, MD, Fayez S. Sarkis, MD, Fernando J. Castro, MD


Objectives: Precolonoscopy dietary regimens often are restricted to clear liquids; however, the superiority of a clear liquid diet (CLD) for bowel preparation quality is ambiguous. We performed a meta-analysis of randomized trials comparing bowel preparation outcomes between a low-residue diet (LRD) or regular diet (RD) compared with a CLD.

Methods: MEDLINE, clinicaltrials.gov, Cochrane Central Register, Scopus, Embase, Cumulative Index to Nursing and Allied Health Literature, and the Web of Science databases were used to conduct a search for randomized controlled trials from 1976 to March 2015. Of 122 relevant references, 12 studies met our inclusion criteria, 7 studies of which were classified as being of high quality. Pooled estimates of bowel preparation quality were defined as adequate versus inadequate. Secondary outcomes included tolerability, willingness to repeat bowel preparation, adverse events, and adenoma detection rate. Pooled estimates of relative risk (RR) were used for dichotomous variables and standardized mean difference for continuous variables.

Results: In the high-quality studies, there were no differences in bowel preparation quality among the LRD/RD and CLD groups (RR 0.98; 95% confidence interval [CI] 0.93–1.04). Analysis of secondary outcomes included all of the studies. Tolerability (RR 1.04, 95% CI 1.01–1.08) and willingness to repeat favored the liberalized diet arm (RR 1.08, 95% CI 1.01–1.16). There was no significant difference in the adenoma detection rate, whereas hunger was more common in the CLD group.

Conclusions: An LRD/RD provided no difference in bowel preparation quality as compared with a CLD. As such, it may be reasonable for patients without risk factors for poor preparation to undergo an LRD until lunch the day before their colonoscopy given that bowel preparation tolerability and willingness to repeat were greater among groups with a liberalized diet.

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