There is good news for people who avoid colonoscopies because of the day-long preparation with a clear liquid cleansing diet. New research shows that consuming small portions of low-residue (low-fiber) solid foods on the day before colonoscopy led to improved colonoscopies, compared with a clear liquid diet.

In addition, people who consumed low-residue foods had more energy on the day before and the day of the procedure, compared with those on a clear liquid diet.

“Colonoscopies prevent death from colorectal cancer, yet millions of people avoid this screening. Many cite dietary restrictions as a deterrent. The clear liquid diet is standard of care [for colonoscopy preparation] in the U.S. We found that low-residue foods led to a better colonoscopy compared to a liquid diet. Also, patients were more comfortable, less hungry, and less fatigued on the morning of colonoscopy,” said lead author Dr. Jason Samarasena, associate professor at the University of California, Irvine. He presented this research at a teleconference at the annual Digestive Disease Week.

In this single-center, randomized trial, people assigned to the low-residue diet could eat small portions of protein, carbohydrate, and fat at three meals on the day before colonoscopy. The group assigned to the clear liquid diet could drink only broth, black coffee, tea, and other clear liquids. Both groups drank standard bowel-cleansing liquid on the night before and the morning of the procedure.

Dr. Samarasena explained that low-residue foods, such as eggs, yogurt, cheese, bread, cottage cheese, chicken nuggets, and macaroni and cheese, are easily broken down in the stomach and cleaned out by the bowel preparation.

“High-residue foods, such as fruit, nuts, or vegetables, don’t break down as much and make it more difficult to visualize the colon,” he said.

The study included 83 patients who underwent colonoscopies at two sites over a 1-year period from 2014 to 2015. An adequate bowel preparation was defined as a Boston Bowel Preparation Scale (BBPS) score greater than 6. All endoscopists were blinded and all colonoscopies were video recorded.

In an interim blinded analysis, the low-residue diet allowed a significantly higher number of adequate bowel preparations, compared with the clear liquid diet group: mean BBPS was 7.98 for the low-residue diet group and 7.54 for the clear liquid diet group (P = .05).

People assigned to the low-residue diet expressed a much higher level of satisfaction for the diet: 97% versus 46% who rated the clear liquid diet satisfactory.

In addition, people assigned to the low-residue group had significantly lower hunger scores on a scale from 1 to 10, with 10 being most hungry on the evening before the colonoscopy (3.5 for the low-residue diet versus 6.9 for the clear liquid diet, P = .001), and lower fatigue scores (3.5 versus 6, respectively, P = .01) on a 10-point scale on the morning of the procedure, compared with the clear liquid diet group.

There was no significant difference between the two groups for mean symptom scores for nausea, vomiting, bloating, abdominal cramping, and overall discomfort.

“Patients slated to undergo colonoscopy often have to miss at least a day of work. A low-residue diet may allow patients to work on the day before the procedure,” Dr. Samarasena noted.

Dr. Samarasena and his coinvestigators plan to enroll more patients for a larger sample size to compare both diets.

“This will be one of the largest studies in the U.S. to evaluate a low-residue diet. We hope this will encourage gastroenterologists in the U.S. to use a low-residue diet and that more patients will then undergo colonoscopy screening,“ he said.