Low-Residue Diet Acceptable for Bowel Prep

Caroline Helwick

May 23, 2016

SAN DIEGO — A diet of low-residue solid foods the day before colonoscopy leads to more effective bowel cleansing than the traditional clear-liquid diet, new research shows.

And patients who followed the low-residue diet "were more comfortable in the 24 hours before the test," said Jason Samarasena, MD, from the University of California, Irvine. They were "less hungry and less fatigued on the morning of the colonoscopy."

This finding is "good news for patients who dread the clear-liquid diet," he said here at Digestive Disease Week 2016. For many people, dietary restrictions the day before colonoscopy are a deterrent to life-saving screening for colorectal cancer, he pointed out.

Dr John Vargo

This study is one of the most important at the meeting, said John Vargo, MD, chair of the Department of Gastroenterology and Hepatology at the Cleveland Clinic's Digestive Disease and Surgery Institute.

"This is an interim analysis," he pointed out, "but the fact is that if patients can eat a low-residue diet, rather than just pure liquids, their satisfaction with and adherence to colonoscopy prep will be markedly improved."

In their study, Dr Samarasena and his colleagues assessed 83 patients undergoing colonoscopy at a tertiary care center and a Veterans Administration hospital.

Patients randomly assigned to the low-residue diet consumed small portions of solid foods, such as protein, carbohydrate, and fat, during meals up until 6:00 PM the day before the procedure.

"Patients could choose foods such as eggs, yogurt, cheese, white bread, chicken breasts, and ice cream," Dr Samarasena explained. "These are foods that are easily liquefied in the small intestine, wash out easily with the prep agent, and therefore do not interfere with colonoscopy."

Those randomly assigned to the clear-liquid diet could drink only broth, black coffee, black tea, and other clear liquids the day before the procedure.

All patients consumed two doses of PEG-ELS purgative — one dose at 6:00 PM the evening before the procedure and the other dose 5 hours before the procedure.

Investigators used the Boston Bowel Preparation Scale (BBPS) to evaluate bowel preparation. They rated hunger and fatigue before and after the procedure on a 10-point scale. They also assessed nausea, vomiting, bloating, abdominal cramping, overall discomfort, satisfaction with the diet, and willingness to repeat the preparation procedure.

Bowel preparation was considered adequate if the BBPS score was higher than 6. "These were considered clean enough to easily detect polyps," Dr Samarasena said.

The low-residue diet performed better than the liquid diet on all measures, according to an interim analysis of the data.

Mean score on the BBPS was higher in the low-residue group than in the liquid diet group (7.98 vs 7.54).

Table. Outcomes for the Two Colonoscopy Preps

Outcome Low-Residue Diet Liquid Diet P Value
Adequate bowel preparation 91% 76% .05
Hunger score, evening before procedure 3.5 6.9 .001
Fatigue score, morning of procedure 3.5 6.0 .01
Satisfaction with diet 97% 46% <.001


There are several reasons the low-residue diet might outperform the liquid diet, Dr Samarasena explained.

Solid foods might have given the patients more energy, which would help them tolerate the purgative, leading to better compliance and superior bowel cleansing. And solid foods might have stimulated natural bowel movements, so the purgative would have less work to do.

Patients could choose foods such as eggs, yogurt, cheese, white bread, chicken breasts, and ice cream.

The study cohort was derived from two very different practice settings. Patients from the Veterans Affairs hospital allowed the researchers to assess how the diet works in patients likely to have comorbidities, he said.

When the final analysis of these data is complete, the researchers plan to evaluate the diet in a larger population.

"We hope our findings will change the way practitioners prepare patients for colonoscopy and increase the population of patients willing to participate in vital screening," Dr Samarasena said.

"It's a fascinating concept," Dr Vargo told Medscape Medical News. "We have thought for so long that it has to be liquids or the highway, but this may not be the case. If we get positive results, this obviously would benefit our patients."

Dr Samarasena reports receiving funding from Medtronic, Medivators, Olympus, and Pentax. Dr Vargo is a consultant for Paion Medical.

Digestive Disease Week (DDW) 2016: Abstract 723. Presented May 23, 2016.


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