Crohn's Disease in Remission
Low Sulfur Diet for Persistent Symptoms in Quiescent Crohn’s Disease
This pilot study is investigating an eight-week low sulfur diet versus a usual diet in adults whose Crohn’s disease is quiescent but who continue to have abdominal pain or diarrhea.
Registry title: A Pilot Study Examining Low Sulfur Diet as Treatment for Persistent Symptoms in Quiescent Crohn's Disease
1 recruiting U.S. site ↓Study at a glance
- Age
- 18 Years and older
- Treatment
- Low Sulfur Diet or Usual Diet
- Design
- Randomized
- Central study contact
- Allen Lee, MD, MS734-936-9454allenlee@umich.edu
- Sponsor
- University of Michigan
Research question
What happens to dietary animal-protein intake, urinary sulfate, and diet tolerability when people with quiescent Crohn’s disease follow a low sulfur diet rather than their usual diet?
Participant snapshot
Who the study is looking for
- The study is looking for adults age 18 or older.
- Participants must have a prior Crohn’s disease diagnosis supported by endoscopy, imaging, and/or tissue findings.
- Crohn’s disease must be quiescent, based on the specified fecal calprotectin result and/or absence of inflammation on a recent colonoscopy.
- Participants must still have abdominal pain and/or diarrhea meeting the study’s symptom-score threshold.
- The listed recruiting site is the University of Michigan in Ann Arbor, Michigan.
Participation overview
What participation may involve
Participants follow either a low sulfur diet or their usual diet for eight weeks, receive nutritionist contact, report dietary information, and complete repeated tests and sample collections. The usual-diet group may optionally follow the low sulfur diet for another eight weeks. What participation may involve: - Complete an initial phone screening and review usual eating habits with a study nutritionist. - Follow the assigned low sulfur or usual diet during the initial eight-week treatment phase. - Attend in-person baseline and week-eight visits for testing and sample collection. - Take part in nutritionist phone visits every two weeks during the initial treatment phase. - If initially assigned to usual diet, optionally follow the low sulfur diet for eight additional weeks with further calls and a final in-person visit. The randomized treatment phase lasts eight weeks. Participants in the usual-diet group who choose the optional low sulfur phase may participate for approximately 16 weeks. The detailed description reports an initial screening call, two in-person visits, and phone follow-ups at weeks 2, 4, and 6 during the first eight weeks. It also describes three additional calls and another in-person visit for the optional extension, but the brief summary reports six phone visits during the study.
Study interventions
What participants may receive or do
- Low Sulfur Diet: Participants assigned to this group follow a low sulfur diet for eight weeks with nutritionist support. The diet reduces animal products such as meat, dairy, and eggs, as well as sulfur additives, while emphasizing fruits, vegetables, whole grains, nuts, seeds, and soy products.
- Usual Diet: Participants assigned to this comparison group continue their usual diet for eight weeks. Those interested may then be offered eight weeks of the low sulfur diet with nutritionist support.
Study design
How the comparison works
This is a pilot interventional study with an estimated 20 participants assigned in parallel to a low sulfur diet or their usual diet. Participants and study staff are not blinded to the assignment. Participants are randomly assigned to either the low sulfur diet or usual-diet group; the registry does not report the assignment ratio. The study uses no masking, so participants and the study team know which diet is assigned. The comparison group continues its usual diet for eight weeks.
Reported activities
Procedures and tests
- Dietary-history review, 24-hour diet recall, and study surveys.
- Meetings or calls with a study nutritionist for diet education, monitoring, and questions.
- Rectal barostat testing to measure rectal or visceral sensation.
- Glucose hydrogen breath testing to assess for small intestinal bacterial overgrowth.
- Lactulose-mannitol testing to evaluate intestinal permeability, sometimes called a leaky-gut test.
- A 24-hour urine collection for sulfate measurement.
- Blood or serum sample collection.
- Stool sample collection.
- Saliva sample collection.
- An optional colonoscopy is listed, but the registry does not explain when it is offered or what it involves.
Eligibility highlights
Details that may affect whether you contact the study
These are selected highlights, not a complete eligibility check. Exact criteria remain in the full registry record below.
Common requirements
- A prior Crohn’s disease diagnosis must be supported by endoscopic, radiographic, and/or histologic findings.
- Crohn’s disease must be quiescent, defined as fecal calprotectin below 150 micrograms per gram of stool within 30 days and/or no inflammation on colonoscopy within 90 days of enrollment.
- Persistent abdominal pain and/or diarrhea must have a T-score of at least 55 on the National Institutes of Health PROMIS-GI symptom scale.
Possible reasons someone may not be able to join
- People who have had a total colectomy are excluded.
- People with an end ileostomy or colostomy in place are excluded.
- Changes in immunosuppressive medications within the previous four weeks are not allowed.
- Antibiotic or probiotic use within the previous four weeks is not allowed.
- People with an active or suspected gastrointestinal stricture or stenosis are excluded.
- People who habitually follow a vegetarian or vegan diet are excluded.
- Participants must be able and willing to follow a low sulfur diet.
- People with a body mass index below 18.5 kg/m² or more than 7.5% unintentional weight loss during the past three months are excluded.
- Pregnancy is excluded, and the criterion includes contraception requirements through the final 13C-mannitol:lactulose test and specific breastfeeding restrictions.
- Participants must agree not to donate sperm, eggs, or breast milk from the study start until the final 13C-mannitol:lactulose test is complete.
Important unknowns
What the record does not make clear
- The brief summary reports two in-person and six phone visits, while the detailed initial eight-week schedule names an initial screening call plus calls at weeks 2, 4, and 6. Additional visits are described only for the optional extension.
- The registry excludes recent changes in immunosuppressive medication but does not explain which Crohn’s treatments may continue or whether they must remain unchanged throughout participation.
- The registry does not describe what happens if Crohn’s inflammation or symptoms worsen during the study.
- An optional colonoscopy is listed among study activities, but its timing, purpose, and conditions are not described. A recent colonoscopy may also be used to document quiescent disease.
- The registry does not state which study-related tests, diet-related expenses, or clinical care costs are covered.
- The registry does not report whether participants are compensated.
- The registry does not report reimbursement or support for travel to the Ann Arbor site.
- The University of Michigan location is marked recruiting, but the registry does not confirm whether a suitable opening is currently available.
Before contacting the site
Questions for the study team
- Exactly how many phone and in-person visits would I have during the eight-week phase and, if chosen, the optional extension?
- Which Crohn’s medications, antibiotics, probiotics, and supplements must remain unchanged or be avoided during the study?
- What would happen if my symptoms or Crohn’s inflammation worsened during either diet phase?
- Is a colonoscopy required, and what does the registry mean by an optional colonoscopy?
- What preparation, discomfort, risks, and recovery time should I expect for the rectal barostat, breath test, and intestinal-permeability test?
- Who pays for study tests, diet-related food expenses, parking, and travel, and is compensation offered?
- If I am assigned to the usual-diet group, what additional commitments come with choosing the optional low sulfur diet afterward?
Before changing care
Questions for your gastroenterologist
- Is my Crohn’s disease stable enough to discuss this study with the research team?
- Could I safely keep my current Crohn’s treatment unchanged while the study team evaluates me?
- What approved treatment or dietary alternatives should I consider for my persistent symptoms before deciding whether to contact the study?
- Are there nutritional or weight-related concerns that would make a low sulfur diet difficult in my clinical situation?
- How should you and the research team coordinate monitoring if my symptoms or inflammation change?
This plain-language digest is provided by the Aidy clinical trials API. It may omit details and is not medical advice or an eligibility decision. Review the full registry record and confirm details with the study team.
Source record
Full registry record
The sections below preserve the study information supplied through ClinicalTrials.gov, including complete descriptions, criteria, outcomes, and locations.
About this study
The goal of this study is to learn about a low sulfur diet in patients with Crohn's disease. Study participants will be randomized to receive a low sulfur diet or usual diet for 8 weeks. Participants will work with study nutritionists and receive dietary educational materials. Participants will attend 2 in-person visits as well as 6 phone visits during the study. In addition, subjects will undergo testing, including a test to measure rectal sensation, a test to look for small intestinal bacterial overgrowth, and a test to measure leaky gut.
Even in the absence of active inflammation, persistent symptoms are reported in up to 46% of inflammatory bowel disease (IBD) patients, especially in Crohn's disease (CD). While persistent symptoms in quiescent Crohn's disease result in worsened quality of life and worse outcomes, evidence-based treatments do not currently exist due to lack of mechanistic understanding of this condition. The gut microbiome, which are the microbes that live in our gut, have been suggested as a potential cause of persistent symptoms. Diet is a major influence on the microbiome and may have a modifiable impact on persistent symptoms in Crohn's disease. However, this has not been well established. The investigators propose a study period of approximately 8 weeks to evaluate the effects of a low sulfur diet in Crohn's disease. Participants will have an initial phone visit to determine eligibility to participate in the study and to review potential participants normal diet with a study nutritionist. The treatment phase of 8 weeks will begin at the baseline visit (week 0). Participants will be randomized to receive a low sulfur diet or usual diet for 8 weeks. Participants on the low sulfur diet will meet with the study nutritionist to receive educational materials and recipes for the low sulfur diet. During this visit, participants will undergo testing, including a rectal barostat test to evaluate rectal sensation, glucose hydrogen breath test to assess for small intestinal bacterial overgrowth, lactulose-mannitol test to evaluate intestinal permeability, and a 24-hour urine sample to measure urine sulfate levels. Participants will be asked to collect saliva, serum, and stool samples. Participants will then have phone visits every 2 weeks (week 2, week, 4, and week 6). Study nutritionists will monitor their dietary history and answer questions about the low sulfur diet if applicable. At the conclusion of the 8 weeks, participants will have a final in-person study visit where rectal barostat, glucose hydrogen breath test, lactulose mannitol testing, and 24-hour urine sulfate level will be repeated. Stool and serum samples will be collected by participants. Optional Low Sulfur Diet for participants randomized to the usual diet: At the conclusion of the study (week 8), if participants randomized to usual diet are interested, will be offered treatment with a low sulfur diet for the next 8 weeks. Participants will meet with the study nutritionist that will provide educational materials on a low sulfur diet. Participants will have phone visits every 2 weeks (week 10, week 12, and week 14) to review dietary history and answer questions about the low sulfur diet. At the conclusion of the 16 weeks, participants will have a final in-person study visit where they will undergo testing, including a rectal barostat test to evaluate rectal sensation, glucose hydrogen breath test to assess for small intestinal bacterial overgrowth, lactulose-mannitol test to evaluate intestinal permeability, and a 24-hour urine sample to measure urine sulfate levels. Participants will be asked to collect saliva, serum, and stool samples.
Study design and administration
- Organization
- University of Michigan
- Organization class
- Other
- Organization study ID
- HUM00218796
- Lead sponsor
- University of Michigan
- Sponsor class
- Other
- Enrollment type
- Estimated
- Allocation
- Randomized
- Intervention model
- Parallel
- Primary purpose
- Treatment
- Masking
- None
- Who is masked
- Not provided
- Standard age groups
- Adult, Older Adult
Study arms
Experimental
Low Sulfur Diet
Participants in this group will follow a low sulfur diet. This diet decreases the amount of animal products (including meat, dairy, and eggs) as well as sulfur additives in the diet. The main types of foods in the low sulfur diet include fruits, vegetables, whole grains, nuts, seeds, and soy products.
Interventions: Other: Low Sulfur Diet
Active Comparator
Usual Diet
Participants in this group will follow a standard of care usual diet for 8 weeks.
Interventions: Other: Usual Diet
Interventions
Other
Low Sulfur Diet
Subjects will be placed on a low sulfur diet for 8 weeks with the support of a nutritionist. In addition, participants will be asked to complete: surveys, lactulose-mannitol test, glucose hydrogen breath test, blood samples, visceral sensation test, 24-hour urine sample for sulfate level, provide stool samples, optional colonoscopy.
Other
Usual Diet
Subjects will continue on their usual diet for 8 weeks. At the end of 8 weeks, if participants are interested, they will be offered treatment with low sulfur diet for 8 weeks with the support of a nutritionist. In addition, participants will be asked to complete: surveys, lactulose-mannitol test, glucose hydrogen breath test, blood samples, visceral sensation test, 24-hour urine sample for sulfate level, provide stool samples, optional colonoscopy.
Eligibility
18 Years and older
All
Not accepted
Inclusion criteria (3)
- Prior diagnosis of Crohn's disease based on endoscopic, radiographic, and/or histologic findingsRegistry-derived · unreviewed
- Quiescent Crohn's disease as defined by fecal calprotectin level less than 150 micrograms/gram (mcg/g) stool and/or absence of inflammation on colonoscopy within 30 and 90 days, respectively, of enrollmentRegistry-derived · unreviewed
- Persistent symptoms will be defined by abdominal pain and/or diarrhea T-scores greater than or equal to 55 by the National Institutes of Health (NIH) Patient-Reported outcomes measurement information system Gastrointestinal scale (PROMIS-GI)Registry-derived · unreviewed
Exclusion criteria (11)
- Prior total colectomyRegistry-derived · unreviewed
- Presence of an end ileostomy or colostomy in placeRegistry-derived · unreviewed
- Changes in immunosuppressive medications within the past 4 weeksRegistry-derived · unreviewed
- Use of antibiotics or probiotics within the past 4 weeksRegistry-derived · unreviewed
- Active or suspected stricture/stenosis of the GI tractRegistry-derived · unreviewed
- Habitual vegetarian or vegan dietRegistry-derived · unreviewed
- Active or suspected gastrointestinal stricture or stenosisRegistry-derived · unreviewed
- Unable or unwilling to follow a low sulfur dietRegistry-derived · unreviewed
- Patients who are underweight as defined by BMI \< 18.5 kg/m2 or have significant unintentional weight loss as defined by \>7.5% body weight in the past 3 monthsRegistry-derived · unreviewed
- Currently pregnant, breastfeeding, and/or unwillingness/inability to use contraception start of the study until the last 13C-mannitol:lactulose test is complete. Sexually active male participants and/or their female partners of reproductive potential must agree to use effective contraception from the start of the study and until the last 13C-mannitol:lactulose test is complete. Women who are breastfeeding must stop breastfeeding during and for at least 12 hours after consuming the 13C-mannitol:lactulose test. Breastfeeding women must pump and dispose of the breastmilk during this time periodRegistry-derived · unreviewed
- Subjects must agree to not donate sperm or ova (eggs) or breast milk from the start of the study until the last 13C-mannitol:lactulose test is complete.Registry-derived · unreviewed
This information can identify a possible match, conflict, or item needing confirmation. Only the study team can determine eligibility.
Study outcomes
Primary outcome
Dietary Protein Intake for both groups as assessed by 24 hour diet recall
Time frame: 8 weeks
Dietary protein intake (animal-based) as assessed by 24 hour diet recall
Primary outcome
Dietary Protein Intake as assessed by 24 hour diet recall
Time frame: Approximately 16 weeks
Dietary protein intake (animal-based) as assessed by 24 hour diet recall. This is for the group that voluntarily goes on the low sulfur diet after standard of care arm is completed.
Primary outcome
Change in 24 hour urinary sulfate
Time frame: 8 weeks
Change in 24 hour urinary sulfate level from baseline
Primary outcome
Change in 24 hour urinary sulfate
Time frame: Approximately 16 weeks
Change in 24 hour urinary sulfate level from baseline. This is for the group that voluntarily goes on the low sulfur diet after standard of care arm is completed
Secondary outcome
Tolerability of Low Sulfur Diet based on the Visual Analog Scale (VAS)
Time frame: Week 4
The VAS has 5 questions in which participants are asked about knowledge, purchase, preparation, ease of following the diet, and overall tolerability of the sulfur diet. Each question participants will score between 0-100 (higher score is more tolerable with total points of 500).
Secondary outcome
Tolerability of Low Sulfur Diet based on the Visual Analog Scale (VAS)
Time frame: Approximately week 12
The VAS has 5 questions in which participants are asked about knowledge, purchase, preparation, ease of following the diet, and overall tolerability of the sulfur diet. Each question participants will score between 0-100 (higher score is more tolerable with total points of 500). This is for the group that voluntarily goes on the low sulfur diet after standard of care arm is completed.
Secondary outcome
Tolerability of Low Sulfur Diet based on the Visual Analog Scale (VAS)
Time frame: Week 8
The VAS has 5 questions in which participants are asked about knowledge, purchase, preparation, ease of following the diet, and overall tolerability of the sulfur diet. Each question participants will score between 0-100 (higher score is more tolerable with total points of 500).
Secondary outcome
Tolerability of Low Sulfur Diet based on the Visual Analog Scale (VAS)
Time frame: Approximately 16 weeks
The VAS has 5 questions in which participants are asked about knowledge, purchase, preparation, ease of following the diet, and overall tolerability of the sulfur diet. Each question participants will score between 0-100 (higher score is more tolerable with total points of 500). This is for the group that voluntarily goes on the low sulfur diet after standard of care arm is completed.
Recruiting locations in the United States
University of Michigan
RecruitingAnn Arbor, Michigan, 48109, United States
Allen Lee, MD, MS734-936-9454allenlee@umich.edu
Allen Lee, MD
Central study contacts
Registry dates
- First posted
- May 8, 2023
- Primary completion
- Dec 30, 2026
- Overall completion
- Apr 30, 2027
Trial information comes from ClinicalTrials.gov and may change. Confirm current status, eligibility, and site details with the study team. Aidy does not provide medical advice or determine eligibility.