Impact of Chewing Gum on Bowel Preparation in Patients Undergoing Colonoscopy

Background and Rationale Colorectal cancer (CRC) remains the second leading cause of preventable cancer-related death in the United States, with approximately 150,000 new cases and 50,000 deaths annually. Colonoscopy is the gold-standard screening modality for CRC because it allows both detection and removal of precancerous lesions within the same procedure. However, the success of colonoscopy depends heavily on adequate bowel cleansing. Suboptimal bowel preparation can lead to missed lesions, prolonged procedure times, and incomplete examinations, ultimately reducing screening effectiveness.

One of the most common barriers to successful colonoscopy completion is the patient's difficulty tolerating bowel preparation. Poor tolerance-due to the taste, volume burden, nausea, bloating, or abdominal discomfort associated with polyethylene glycol (PEG)-based solutions-can result in incomplete ingestion of the prep solution and inadequate cleansing. These experiences often discourage patients from future screening, contributing to low adherence to recommended screening guidelines, particularly among underserved populations.

Chewing gum has been proposed as a simple and low-cost adjunct that could improve tolerance to bowel preparation. The act of chewing gum stimulates cephalic-vagal pathways through "sham feeding," promoting gastrointestinal motility without adding calories or affecting electrolyte balance. In postoperative and perioperative gastrointestinal contexts, gum chewing has been shown to accelerate recovery of bowel function. A few small randomized controlled trials (RCTs) have evaluated gum chewing during bowel preparation, with mixed results. The largest study, conducted in China (n=300), found no improvement in cleansing quality but higher patient satisfaction. Other smaller studies in Turkey and elsewhere suggested improved tolerability and, in some regimens, enhanced cleansing scores.

To date, no prospective, randomized, endoscopist-blinded studies in the United States have investigated the impact of gum chewing on bowel preparation quality and patient experience using modern split-dose PEG regimens. Furthermore, no study has systematically compared outcomes between high-volume (4L PEG) and low-volume (2L PEG + ascorbate) preparations-two regimens that differ in both cost and tolerability and are commonly prescribed based on insurance coverage and comorbidities.

This study aims to address this gap by testing whether a benign, widely available behavioral intervention-chewing sugar-free gum before and after split-dose bowel preparation-can improve tolerance, satisfaction, and potentially the quality of bowel cleansing.

Study Objectives

Primary Objective:

To determine whether chewing sugar-free gum before and after split-dose bowel preparation improves bowel cleansing quality, measured by the Boston Bowel Preparation Scale (BBPS), compared with standard bowel preparation alone.

Secondary Objectives:

• To evaluate whether gum chewing improves patient tolerance to bowel preparation (nausea, bloating, cramping, discomfort).
• To assess overall satisfaction with the preparation process and willingness to repeat the prep in the future.
• To compare prep completion rates between the gum-chewing and control groups.
• To evaluate cecal intubation rates, procedure metrics (withdrawal time, total duration), and adenoma detection rates (ADR).
• To explore differences in outcomes between high-volume (4L PEG) and low-volume (2L PEG + ascorbate) subgroups.

Study Design This is a single-center, prospective, randomized, endoscopist-blinded controlled trial conducted at the University of Maryland Medical System (UMMC Midtown Campus) Outpatient Endoscopy Suite in Towson, Maryland.

Participants will be randomized in a 1:1 ratio to either:

Experimental Arm: Standard split-dose PEG bowel preparation + chewing sugar-free gum before and after the prep, or Active Comparator Arm: Standard split-dose PEG bowel preparation without gum chewing.

Both arms will undergo standard colonoscopy for clinical indications (screening, surveillance, or diagnostic).

Randomization will be performed using a computer-generated randomization sequence with equal allocation (n = 80 per arm, total n = 160). Endoscopists assessing bowel cleansing will remain blinded to group assignment.

Study Procedures

Recruitment and Consent:

Eligible patients will be identified during routine clinic visits when their colonoscopy is scheduled. The study will be explained by the principal investigator or trained research personnel in a private setting, and informed consent will be obtained.

Study Activities:

• Randomization (1:1) will occur after consent.
• Participants will follow their assigned bowel prep instructions.
• Nursing staff will record tolerance and satisfaction scores during pre-procedure intake.
• The blinded endoscopist will assess bowel cleansing using the Boston Bowel Preparation Scale (BBPS).

Additional data (prep completion, cecal intubation, procedure metrics, and ADR) will be abstracted from the electronic medical record.

Duration per Participant:

Each participant's involvement lasts approximately 24 hours-the time required to complete bowel preparation and the colonoscopy procedure. There is no post-procedure follow-up required for study purposes.

Total Study Duration:

The overall study is expected to take approximately two months, including start-up, enrollment, and analysis phases.

Sample Size and Statistical Analysis

Sample Size Calculation:

Assuming a moderate effect size (Cohen's d = 0.40) for improvement in tolerance/satisfaction, with a one-sided α = 0.05 and 80% power, approximately 78 participants per arm would be required. To accommodate potential dropouts and missing data, the investigators plan to enroll 160 participants total (80 per arm).

Analysis Plan:

Primary analysis: Comparison of mean total BBPS scores between the gum and control arms using a two-sample t-test or nonparametric equivalent (Wilcoxon rank-sum).

Secondary analyses:

• Chi-square or Fisher's exact tests for categorical variables (adequate vs inadequate cleansing, ADR, completion rates).
• Multivariable regression models to adjust for confounders (age, sex, BMI, prep type, comorbidities).
• Subgroup analyses comparing high-volume vs low-volume prep regimens.
• A p-value < 0.05 will be considered statistically significant.
• All analyses will be performed using de-identified data in a secure research environment (SRE).

Risks and Safety Considerations Chewing sugar-free gum is a low-risk activity. Potential risks include mild jaw discomfort, accidental swallowing of gum, or rarely choking. Participants will be instructed to chew only when seated and alert, to discard the gum after use, and to report any discomfort.

The bowel preparation carries standard, well-known risks such as nausea, bloating, cramps, or vomiting. Severe adverse events (e.g., dehydration, electrolyte imbalance, allergic reaction to PEG) are rare and will be managed per institutional protocols. Participants have access to clinical staff and an on-call physician for any adverse effects.

Loss of confidentiality is a minor risk; all identifying information will be stored separately from study data using password-protected, HIPAA-compliant systems.

Potential Benefits Participants may experience improved comfort or satisfaction during bowel preparation, although direct benefit cannot be guaranteed. The study findings may provide important information to improve the tolerability of colonoscopy preparation, enhance patient adherence, and ultimately support more effective colorectal cancer prevention strategies.

Data Management and Confidentiality Data will be abstracted from the electronic medical record (EPIC) and entered into an encrypted, password-protected Excel database within the Secure Research Environment (SRE). Identifiers such as name, date of birth, and medical record number will be used only for linkage and stored separately from analytic data. Each participant will be assigned a unique study ID. Access to data will be limited to authorized study personnel.

Research data will not be reused for other projects without IRB approval. De-identified aggregate results will be presented at scientific meetings and published in peer-reviewed journals.

Monitoring Plan Given the minimal-risk nature of the behavioral intervention, a formal data safety monitoring board (DSMB) is not required. The Principal Investigator will review all reported adverse events and protocol deviations, and any unanticipated problems will be reported promptly to the institutional IRB.

Ethical Considerations The study will be conducted in accordance with the ethical principles of the Declaration of Helsinki and the U.S. Common Rule (45 CFR 46). Informed consent will be obtained from all participants prior to enrollment. Participation is voluntary, and refusal or withdrawal will not affect clinical care.

Dissemination Plan Participants may opt to receive a lay summary of the results after study completion. Individual participant-level data will not be shared outside the research team.

Inclusion criteria

• Age 45-75 years
• Scheduled for elective outpatient colonoscopy
• Able to provide informed consent

Exclusion criteria

• Prior major abdominal surgery (excluding appendectomy or cholecystectomy)
• Pregnancy
• Cognitive impairment
• Ward of the state
• Known allergy to PEG or gum components
• Current use of GI prokinetics
• Known temporomandibular joint (TMJ) disorder or difficulty chewing/swallowing