Impact of Dietary Fiber Supplementation on Colonic Microbiome

Not Applicable

Recruiting

• Conditions: Benign Colorectal Neoplasm; Non-Neoplastic Anal Disorder
• Interventions: Dietary Supplement: Dietary Fiber; Procedure: Proctoscopy or anoscopy with Biopsy; Procedure: Colonoscopy; Other: Questionnaire Administration

• Registration Number: NCT05643859
• Lead Sponsor: OHSU Knight Cancer Institute

Brief Summary

This clinical trial tests whether daily fiber supplementation will change the mucosal microbiome of the colon. The microbiome are microorganisms that live in the human gut. They serve a vital role in maintaining health. Certain microbial strains are associated with the growth of colon polyps, which eventually could go on to form colon cancer. Giving dietary fiber supplements may help prevent precancerous polyps from ever developing.

Detailed Description

PRIMARY OBJECTIVE:

I. To identify how diet, specifically fiber supplementation, alters the microbiome of the colonic mucosa.

OUTLINE:

Patients receive dietary fiber orally (PO) once daily (QD) for 28 days. Patients may undergo standard of care proctoscopy or anoscopy with biopsy on study and at follow up or may undergo standard of care colonoscopy on study. All patients also undergo collection of blood samples on study and at follow up.

Study Timeline

• Study First Submitted: 2022-09-26
• Study First Submitted QC: 2022-12-01
• Study First Posted: 2022-12-09
• Study Start: 2023-04-01
• Status Verified: 2025-05
• Last Update Submitted: 2025-05-20
• Last Update Posted: 2025-05-23
• Primary Completion: 2025-12-31
• Study Completion: 2025-12-31

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 120

Inclusion Criteria

• Age >= 18 years
• Ability to understand and the willingness to sign a written informed consent document
• Patients who present with a chief complaint of a benign anorectal pathology including hemorrhoids, anal fissures, and anal fistulas without underlying conditions such as colorectal cancer or Crohn's disease or are undergoing a standard of care colonoscopy procedure

Exclusion Criteria

• Patients with an active malignancy, Crohn's disease, ulcerative colitis, and immunosuppressed patients
• Patients with hereditary colon cancer syndrome including Lynch syndrome or Familial Adenomatous Polyposis (FAP)
• Patients with a prior history of total or partial colon resection
• Colorectal pathology, such cancer or proctitis, after initial study scope

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Supportive care (oral fiber)	Dietary Fiber	Patients receive dietary fiber PO QD for 28 days. Patients may undergo standard of care proctoscopy or anoscopy with biopsy on study and at follow up or may undergo standard of care colonoscopy on study. All patients also undergo collection of blood samples on study and at follow up.
Supportive care (oral fiber)	Questionnaire Administration	Patients receive dietary fiber PO QD for 28 days. Patients may undergo standard of care proctoscopy or anoscopy with biopsy on study and at follow up or may undergo standard of care colonoscopy on study. All patients also undergo collection of blood samples on study and at follow up.
Supportive care (oral fiber)	Colonoscopy	Patients receive dietary fiber PO QD for 28 days. Patients may undergo standard of care proctoscopy or anoscopy with biopsy on study and at follow up or may undergo standard of care colonoscopy on study. All patients also undergo collection of blood samples on study and at follow up.
Supportive care (oral fiber)	Proctoscopy or anoscopy with Biopsy	Patients receive dietary fiber PO QD for 28 days. Patients may undergo standard of care proctoscopy or anoscopy with biopsy on study and at follow up or may undergo standard of care colonoscopy on study. All patients also undergo collection of blood samples on study and at follow up.

Primary Outcome Measures

Name	Time	Method
Change in microbiome colonic mucosa: taxa abundance	Baseline and post-supplementation, up to 40 days	Will use data visualization techniques to understand the data and determine if microbiome count overall (richness) changes occur in patients who are started on fiber supplementation. In order to visualize overall changes after fiber supplementation, will generate plots showing relative abundance of the detected taxa for each subject at baseline and post-supplementation. For each taxa, will generate box plots to visually compare the median and interquartile range (IQR) of abundance between the two time points. Wilcoxon signed rank tests with an alpha level of 0.05 will determine if there is a difference in microbial derived short chain fatty acids after fiber supplementation in the blood and mucosa. Wilcoxon signed rank tests with an alpha level of 0.05 will determine if there is a difference in microbial derived short chain fatty acids after fiber supplementation in the blood and mucosa.
Change in microbiome colonic mucosa: microbiome diversity	Baseline and post-supplementation, up to 40 days	Will use data visualization techniques to understand the data and determine if the types of metabolites (microbiome diversity) cases occur in patients who are started on fiber supplementation. In order to visualize overall changes after fiber supplementation. To assess for changes in microbiome diversity, our primary analysis will compare median Shannon diversity index values at baseline and post-supplementation. The Shannon index estimates diversity using richness and abundance. Will calculate Shannon index values for each participant at each time point and use a Wilcoxon signed rank test with an alpha level of 0.05 to determine if there is a difference in microbiome diversity after fiber supplementation.

Trial Locations

Locations (1)

OHSU Knight Cancer Institute; 🇺🇸 Portland, Oregon, United States