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Impact of Dietary Fiber Supplementation on Colonic Microbiome

Changes in Colonic Microbiome With Fiber Supplementation

Who can join

Ages 18 and older · All sexes

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

About the study

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.

What is being tested

• Dietary Fiber (dietary supplement)
• Proctoscopy or anoscopy with Biopsy (procedure)
• Colonoscopy (procedure)
• Questionnaire Administration (other)

Sponsor: OHSU Knight Cancer Institute · Participants: 120 · Started: Apr 1, 2023

Contact the study team

• Shahrose Rahman, M.D. · Phone: 503-494-8652

Official record on ClinicalTrials.gov — NCT05643859

Locations in the U.S.

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.