Digestive Disease Week

Digestive Disease Week

Perspective from John J. Vargo, MD, MPH
June 01, 2016
3 min read

Low residue diet may be superior to clear liquid diet for colonoscopy bowel prep

Perspective from John J. Vargo, MD, MPH
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SAN DIEGO — A less restrictive low residue diet may improve colonoscopy bowel preparation quality compared with a clear liquid diet, according to interim randomized controlled trial data presented at Digestive Disease Week 2016. The study also showed the low residue diet improved patient satisfaction and tolerability, and could help to increase patient participation in colorectal cancer screening programs.

“Colon cancer deaths can be prevented by colonoscopy, yet participation in screening and prevention programs remains too low,” Jason B. Samarasena, MD, associate clinical professor of medicine in the division of gastroenterology and hepatology at the University of California, Irvine, said during his presentation. “Patients often cite bowel preparation and associated dietary restrictions as deterrents to having colonoscopy performed, and despite data supporting the use of low residue diet over clear liquid diet regimen, adoption in the United States has been slow.”

Between November 2014 and November 2016, Samarasena and colleagues randomly assigned 83 adults to consume a standard clear liquid diet or a planned low residue diet the day before their outpatient colonoscopy at a tertiary care center and a VA hospital. All patients also received a standard 4L split-dose PEG-ELS regimen.

Throughout the day before their colonoscopy, “the low residue group was allowed small portions of protein, carbohydrate and fat at three meals,” Samarasena said during a press conference. “Patients could choose between foods such as eggs, yogurts or cheeses, bread, butter, rice, lunchmeat, chicken breast and ice cream.”

The researchers then compared bowel preparation quality, determined by a blinded physician who assessed videos of the procedures using the Boston Bowel Preparation Score, as well as patient tolerance and satisfaction.

The mean Boston Bowel Preparation Score was 7.98 with the low residue diet vs. 7.54 with the clear liquid diet, which was not statistically significant; however, the low residue diet group had significantly more adequate bowel preparations (91.3% vs. 75.7%; P = .05).

Mean symptom scores for nausea, vomiting, bloating, abdominal cramping and overall discomfort did not significantly differ between groups. Patients in the low residue diet group were significantly less hungry the evening before colonoscopy (3.5 vs. 6.9 on a 10-point scale; P = .001), but hunger scores were not significantly different the morning of colonoscopy.

“Patients in the low residue diet group had less fatigue than patients in the clear liquid diet group on the evening before colonoscopy,” Samarasena said. “There appeared to be a trend toward a similar result on the morning of colonoscopy, although this was not statistically significant.”

Finally, 97% of patients in the low residue diet group reported they were satisfied with the diet compared with 46% of patients in the clear liquid diet group (P < .001).

“This interim analysis demonstrates that patients using a low residue diet before colonoscopy achieve a bowel preparation quality that may be superior to patients on a clear liquid diet restriction,” Samarasena said. “This study shows a low residue diet improves patient satisfaction and results in significantly better tolerability of bowel preparation through decreased hunger and fatigue. These results are in line with the most recent ASGE guidelines on bowel preparation, which endorse the use of low residue diet prior to colonoscopy, and as a less restrictive dietary regimen, a low residue diet may help alleviate patient concerns with bowel preparation experience and potentially improve patient participation in colorectal cancer prevention programs.” – by Adam Leitenberger


Samarasena JB, et al. Abstract #723. Presented at: Digestive Disease Week; May 21-24, 2016; San Diego.

Disclosures: Samarasena reports consulting for Medtronic, Medivators, Olympus and Pentax, and speaking and teaching for Medtronic. Please see the DDW disclosure list for all other researchers’ relevant financial disclosures.