The Role of Fiber in the Prevention and Treatment of Fecal Incontinence

The purpose of this study is to determine the effect of fiber supplementation on the fecal metagenome and metabolome in relation to symptoms and anorectal physiology in post-menopausal women with irritable bowel syndrome with diarrhea suffering from liquid stool fecal incontinence (FI.)

Study Overview

• Status: Completed
• Conditions: Irritable Bowel Syndrome With Diarrhea; Fecal Incontinence
• Intervention / Treatment: Dietary supplement: Psyllium

Detailed Description

This is an open-label, single-arm study at Massachusetts General Hospital that aims to recruit post-menopausal female patients with solid stool fecal incontinence. The investigators hope that subjects taking a daily fiber supplement will experience reduced episodes and symptoms of fecal incontinence, measured through quality of life questionnaires and daily stool and food diaries. Subjects will undergo 2 anorectal manometry procedures. Stool samples will also be collected for metabolomic and metagenomic analysis.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02114
      • Massachusetts General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Female, post-menopausal
2. Age 50-90 years old
3. BMI >18.5 and <40 kg/m2
4. Rome IV criteria for liquid stool fecal incontinence occurring at least twice per month
5. At least one FI episode during the run-in period
6. Compliant with reporting during run-in (completion of two 3-day food diaries and two 7-day bowel diaries)
7. Submission of two stool samples during the run-in period
8. Ability to follow verbal and written instructions
9. Informed consent form signed by the subjects

Exclusion Criteria:

1. Less than two episodes per month of liquid stool fecal incontinence
2. Non-compliance with reporting during run-in
3. Patients reporting laxative, enema, and/or suppository usage during the run-in period
4. GI tract structural abnormality that would increase likelihood of obstruction
5. Dysphagia, swallowing disorder, or history of esophageal structural lesions
6. History of GI lumen surgery within 60 days prior to entry into the study
7. Neurological disorders, metabolic disorders, or other significant disease that would impair their ability to participate in the study
8. Inability to tolerate or contraindication to performance of anorectal manometry
9. Celiac disease, Crohn's disease, ulcerative colitis
10. Current anorectal fistula and/or abscess
11. Age <50 or >90
12. BMI of <18.5 or ≥40 kg/m2
13. History of allergic reaction to psyllium
14. Previous trial of soluble fiber supplementation for fecal incontinence within the previous 30 days
15. History of sacral nerve stimulator or artificial anal sphincter placement
16. Administration of investigational products within 1 month prior to Screening Visit
17. Subjects anticipating surgical intervention during the study

19. History of intestinal stricture (e.g., Crohn's disease) 20. History of intestinal obstruction or subjects at high risk of intestinal obstruction including suspected small bowel adhesions 21. History of malabsorption 22. Any other clinically significant disease interfering with the assessments of psyllium, according to the Investigator (e.g., disease requiring corrective treatment, potentially leading to study discontinuation) 23. Any relevant biochemical abnormality interfering with the assessments of psyllium, according to the Investigator 24. Patients with metallic implants within a 30 cm radius of the TAMS electromagnetic coil 25. Currently on opioids 26. Patients with severe cardiac disease, chronic renal failure, or previous GI surgery EXCEPT cholecystectomy, appendectomy, Nissen fundoplication, and partial colectomy 27. Patients with neurological diseases and increased intracranial pressure 28. Patients with impaired cognizance 29. Previous pelvic surgery/radiation, radical hysterectomy 30. Patients with Ulcerative Colitis or Crohn's Disease 31. History of or current rectal prolapse 32. Previous history of anal fissure, anal surgery (abscess), congenital anorectal malformation, fistulae or inflamed hemorrhoids 33. Pregnant women 34. Use of antibiotics in previous 60 days

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Psyllium fiber supplement treatment; All patients will receive psyllium fiber in the form of edible bars, 7g, twice a day to total 14g per day.	Dietary supplement: Psyllium; Psyllium fiber powder baked into a bar is commonly used as a first line of treatment for patients with fecal incontinence.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Stool Metagenomics Assessed by Sequence-based Microbial Communities and Rare Taxa	The Shannon Diversity Index is a measure of within-sample microbial diversity that incorporates both the number of microbial taxa present (i.e., richness) and the distribution of their relative abundances (i.e., evenness). It is calculated using the relative abundance of observed taxa within each stool sample. Higher values indicate greater microbial diversity. The theoretical minimum value is 0, and there is no fixed theoretical maximum because the upper bound depends on the number of taxa detected in a sample and sequencing depth. In human gut microbiome studies, observed values commonly range from approximately 2 to 6.	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Stool Butyrate Abundance Measured by Untargeted LC-MS Metabolomics	Butyrate was measured in stool samples using untargeted LC-MS metabolomics performed by Metabolon. Values were batch-normalized by dividing each sample value by the batch-specific median for butyrate, and missing values were imputed using the minimum observed value across batches. The resulting values were log-transformed before analysis. Higher values indicate greater relative abundance of butyrate in stool. Because this measure reflects relative abundance rather than absolute concentration, there is no fixed theoretical range.	Change from baseline to final visit. Through study completion, up to 6 weeks.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Fecal Incontinence Severity Assessed by Fecal Incontinence Severity Index (FISI)	Questionnaire about the severity of symptoms in those with fecal incontinence. Consists of 4 questions, each rated on a scale of 1 to 6. Lower scores indicate higher severity of symptoms. (Min, 4, max 24)	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Fecal Incontinence Quality of Life Assessed by Fecal Incontinence Quality of Life (FIQL)	Questionnaire about the quality of life of those with fecal incontinence. Questions are rated from 1 to 4 in each of 4 sections. Lower rating represent worse quality of life and higher scores represent higher quality of life. (Min 4, max, 16)	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Anal Squeeze Pressure Assessed by Anorectal Manometry	Squeeze pressure assessed using a pressure sensory for Anorectal manometry (ARM) procedure performed to measure anal and rectal muscle function and sensation.	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Lumbo and Sacral Nerve Latency Assessed by Translumbosacral Anorectal Magnetic Stimulation	Translumbosacral anorectal magnetic stimulation (TAMS) performed during the ARM procedure to measure the change in the nerve conduction between the spinal cord and rectum.	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Relief Assessed by the Global Assessment of Relief	A 7-point scale indicating overall fecal incontinence symptom relief where 1 represents completely relieved and 7 represents completely worse.	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Bloating Scale Assessed by a Bloating Scale	A 10-point scale indicating bloating severity where 0 represents the least severity and 10 represents the most severity.	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Urgency Assessed by an Urgency Scale	A 10-point scale indicating urgency severity where 0 represents the least severity and 10 represents the most severity	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Flatus Assessed by a Flatus Scale	A 10-point scale indicating flatus severity where 0 represents the least severity and 10 represents the most severity	Change from baseline to final visit. Through study completion, up to 6 weeks.
Change in Waist Circumference Measurement	A measure of the subject's waist circumference in the area where the most bloating is experienced	Change from baseline to final visit. Through study completion, up to 6 weeks.

Collaborators and Investigators

• Sponsor: Massachusetts General Hospital
• Collaborators: National Institutes of Health (NIH)
• Investigators: Principal Investigator: Kyle Staller, MD MPH, Massachusetts General Hospital

Study record dates

Study Major Dates

• Study Start (Actual): July 21, 2021
• Primary Completion (Actual): December 11, 2024
• Study Completion (Actual): December 11, 2024

Study Registration Dates

• First Submitted: March 8, 2021
• First Submitted That Met QC Criteria: March 16, 2021
• First Posted (Actual): March 19, 2021

Study Record Updates

• Last Update Posted (Actual): June 30, 2026
• Last Update Submitted That Met QC Criteria: June 24, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Irritable Bowel Syndrome; IBS; IBS-D; Fecal Incontinence; FI; Irritable Bowel Syndrome with Diarrhea
• Additional Relevant MeSH Terms: Intestinal Diseases; Digestive System Diseases; Gastrointestinal Diseases; Rectal Diseases; Colonic Diseases; Colonic Diseases, Functional; Irritable Bowel Syndrome; Fecal Incontinence; Plant Extracts; Plant Preparations; Biological Products; Complex Mixtures; Psyllium
• Other Study ID Numbers: 2021P000691

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No