Ditch the clear liquid diet before colonoscopy?

Last Updated: 2016-05-25

By Megan Brooks

NEW YORK (Reuters Health) - Patients don't need to stick to a clear liquid diet the day before screening colonoscopy, a new study suggests.

In fact, the study found that patients who ate a "low-residue" diet were better prepared for their colonoscopies than those who stuck to the conventional liquid diet.

"The low-residue diet contains foods that are easily liquified in the small intestine and then can be washed out easily with the bowel preparation agent and therefore doesn't really interfere with the colonoscopy procedure," lead researcher Dr. Jason Samarasena from University of California, Irvine, explained during a press briefing.

"We also hypothesize that the solid food can stimulate bowel movements before taking the purgative liquid making the final cleansing process easier. We further hypothesize that the foods in the low-residue diet give patients a higher energy level and possibly making them more tolerant of the entire process," he added.

Dr. Samarasena reported an interim analysis of the study May 23 in San Diego at Digestive Disease Week 2016.

The study involved 83 patients who underwent colonoscopies at a Veteran's Administration Hospital and a tertiary care facility. The researchers compared results from patients who had been randomly assigned to consume only a clear liquid diet on the day before colonoscopy or to eat a planned low-residue diet that included small portions of select solid foods such as eggs, white bread, cheese, white rice and chicken breast.

"Our primary endpoint was bowel cleansing as the cleansing process really is the most important aspect of the colonoscopy; the cleaner the colon, the more polyps are detected and removed safely," Dr. Samarasena said.

In the low-residue group there was a significantly higher number of adequate bowel preparations based on the Boston Bowel Preparation Score (p=0.05).

Satisfaction with assigned diet was reported in significantly more patients in the low-residue group than the clear liquid group (97% vs. 46%, p<0.001).

The low-residue group also reported significantly lower hunger scores on the evening of the prep process (p=0.001) as well as lower fatigue scores on the morning of their colonoscopy (p=0.01).

"With the clear liquid diet, patients often miss a day of work because of the fasting requirement while the low-residue diet may enable patients to carry on more of their normal activities the day before colonoscopy because the restriction is less drastic," Dr. Samarasena told the briefing.

"This interim analysis will be followed up with a final analysis on a larger sample size and this will be one of the largest study in the U.S. on low residue diets for bowel preparation for colonoscopy," he added. "We really hope this will change the way practitioners prepare their patients for colonoscopy and in turn help increase patients' willingness to participate in this vital screening procedure."