Using Breath Tests to Study Gut Sulfur Changes During Dietary Therapy (Sulfur-UC)

Sulfur on the Breath: Using Breath Biomarkers to Monitor Gut Microbial Sulfur Metabolism During Elemental and Reduced Sulfur Dietary Therapy

This study aims to test whether a short liquid-based diet, followed by a low-sulfur eating plan, is safe, manageable, and helpful for people with mild to moderate ulcerative colitis. Investigators want to see if this approach can improve gut health, lower inflammation, and reduce symptoms. Investigators will also test breath samples as an easy, non-invasive way to track gut bacteria activity and disease changes. Investigators believe this diet plan can reduce harmful gut bacteria that produce irritating sulfur compounds, leading to better gut health and measurable improvements that can be detected through breath testing.

Study Overview

• Status: Not yet recruiting
• Conditions: Ulcerative Colitis (UC)
• Intervention / Treatment: Dietary supplement: Elemental formula (mBiota Elemental, Good LFE, Santa Monica, CA); Behavioral: Reduced Sulfur diet; Behavioral: Habitual Diet

Detailed Description

Purpose To determine whether a short-term elemental diet followed by a reduced sulfur diet is a safe, tolerable, and effective non-pharmacologic strategy to improve clinical outcomes, reduce inflammation, and beneficially modulate the gut microbiome in adults with mild-to-moderate ulcerative colitis. A secondary purpose is to validate breath-based biomarkers as non-invasive tools to monitor sulfur metabolism and disease activity. Breath biomarkers include volatile organic compounds (VOCs) and exhaled breath condensate (EBC) to assess sulfur-related metabolites.

Hypothesis A 2-week elemental diet followed by a 10-week reduced sulfur diet will reduce intestinal inflammation and improve clinical outcomes by shifting the gut microbiome away from pro-inflammatory, sulfur-metabolizing bacteria, resulting in reduced sulfur metabolite production detectable through exhaled volatile organic compounds and exhaled breath condensate.

Justification Despite advances in biologic therapies, many UC patients fail to achieve sustained remission, and current treatments do not address upstream drivers such as diet-microbiome interactions. Elemental diets have demonstrated efficacy in Crohn's disease but remain understudied in UC. Emerging evidence links dietary sulfur, microbial sulfur metabolism, and toxic metabolites to UC pathogenesis. This study addresses critical gaps by testing a feasible dietary intervention and validating non-invasive breath biomarkers for real-time disease monitoring and precision nutrition.

Objectives

• Evaluate the clinical efficacy, safety, and feasibility of an elemental diet followed by an reduced sulfur diet.
• Characterize changes in gut microbiome composition, inflammatory markers, and sulfur-related metabolic outputs.
• Validate breath-based volatile organic compounds and exhaled breath condensate as biomarkers of sulfur metabolism and treatment response.
• Identify microbial and metabolic signatures predictive of dietary response.

Research Design A prospective, randomized, controlled trial in adults with mild-to-moderate UC. All participants complete a 2-week elemental diet, followed by randomization (2:1) to either a reduced sulfur diet group (intervention group) or return to habitual diet group (control group) for 10 weeks. Clinical indices, inflammatory biomarkers, stool microbiome profiles and breath samples are collected longitudinally. The initial 2-week elemental diet is applied uniformly to standardize baseline microbial and metabolic conditions prior to randomization and does not replace or delay clinical care decisions.

Statistical Analysis Primary outcomes will be assessed using within- and between-group comparisons of clinical and biochemical response at week 12. Microbiome and metabolomic data will be analyzed using multivariate and differential abundance methods. Correlations between breath biomarkers, microbiome features, and clinical outcomes will assess sensitivity and specificity.

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Natasha Haskey, PhD; Phone Number: 250-807-9597; Email: natasha.haskey@ubc.ca

Study Locations

• Canada
  • British Columbia
    • Kelowna, British Columbia, Canada, V1V 1V7
      • University of British Columbia-Okanagan
      • Contact: Natasha Haskey, RD, PhD; Phone Number: 250-807-9597; Email: natasha.haskey@ubc.ca
      • Principal Investigator: Natasha Haskey, RD, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 19-70 years.

  =Diagnosis of mild-to-moderate ulcerative colitis, defined by a partial Mayo score (pMayo) of 2-7.

• Evidence of active inflammation at enrollment, defined as:
• C-reactive protein (CRP) > 5 mg/L; or
• Fecal calprotectin (FCP) > 200 µg/g.
• Receiving stable medical therapy for ulcerative colitis for at least 8 weeks prior to enrollment.
• No corticosteroid use at the time of recruitment.
• Under consideration by the treating physician for treatment escalation or biologic switch due to inadequate response to current therapy.

Exclusion Criteria:

• Partial Mayo score (pMayo) > 7.
• Pregnant or breastfeeding.
• Body mass index (BMI) < 18 kg/m².
• History of an eating disorder.
• Severe psychiatric disorder.
• Severe medical conditions, including:
• Active cancer;
• Significant cardiovascular disease;
• Diabetes mellitus; or
• Severe food allergies.
• Known allergy or intolerance to corn, dextrose, or maltodextrin.
• Antibiotic use within 3 months prior to enrollment.
• Probiotic use within 3 months prior to enrollment.
• Use of herbal anti-inflammatory supplements during the study period, including but not limited to:
• Serrapeptidase;
• Curcumin;
• Boswellia; or
• Bromelain.
• History of major gastrointestinal surgery, including:
• Ostomy;
• Total colectomy; or
• Short bowel syndrome.
• Inability or unwillingness to comply with study procedures, including anticipated travel or other commitments that may interfere with participation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Reduced Sulfur Diet; Participants will consume a novel elemental formula (mBiota Elemental, Good LFE, Santa Monica, CA) as their sole source of nutrition for two weeks. followed by a 10-week reduced sulfur diet. The reduced sulfur diet is designed to limit dietary sources of sulfur-containing compounds that may contribute to hydrogen sulfide production by the gut microbiota.	Dietary supplement: Elemental formula (mBiota Elemental, Good LFE, Santa Monica, CA); Elemental liquid diets (EDs) are a subset of Exclusive Enteral Nutrition (EEN). Similar to EEN, they are nutritionally complete formulas, but differ in that they consist of free amino acids, monosaccharides, and fatty acids instead of whole, intact macronutrients, which are designed for optimal digestibility and to minimize antigenicity. EDs have been shown to reduce immune activation, favourably modulate the microbiota, suppress proinflammatory cytokines, support epithelial repair, and exclude common dietary additives that may provoke inflammation.; Behavioral: Reduced Sulfur diet; This diet excludes high sulfur foods (e.g., red meat, seafood, eggs), cruciferous vegetables, dried fruits, and fermented beverages. It also accounts for sulfate intake from drinking water and processed food additives.
Active Comparator: Habitual Diet; Participants will complete a 2-week elemental diet intervention followed by a 10-week habitual diet. Participants will be instructed to resume and maintain their usual dietary intake without specific sulfur-restriction recommendations.	Dietary supplement: Elemental formula (mBiota Elemental, Good LFE, Santa Monica, CA); Elemental liquid diets (EDs) are a subset of Exclusive Enteral Nutrition (EEN). Similar to EEN, they are nutritionally complete formulas, but differ in that they consist of free amino acids, monosaccharides, and fatty acids instead of whole, intact macronutrients, which are designed for optimal digestibility and to minimize antigenicity. EDs have been shown to reduce immune activation, favourably modulate the microbiota, suppress proinflammatory cytokines, support epithelial repair, and exclude common dietary additives that may provoke inflammation.; Behavioral: Habitual Diet; Participants randomized to the comparator group will continue their usual dietary intake for 10 weeks without specific dietary restrictions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Composite clinical and biochemical response	Composite clinical and biochemical response at week 12, defined as >30% and >1-point reduction in pMayo score from baseline, plus rectal bleeding subscore decrease of >1 or an absolute subscore <1, with fecal calprotectin <250 μg/g and CRP <5 mg/L.	Baseline, Week 2 and week 12

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stool Biomarkers	fecal calprotectin, shotgun metagenomics (microbiome composition, sulfur metabolizing bacteria), and targeted metabolomics (e.g., hydrogen sulfide, thiosulfate)	Baseline, week 2 and week 12
C-Reactive Protein (CRP) concentration	Serum CRP concentration will be measured to assess systemic inflammation.	Baseline, week 2 and week 12
Complete Blood Count (CBC) parameters	CBC parameters, including hemoglobin, white blood cell count, platelet count, and differential counts, will be measured.	Baseline, week 2 and week 12
Serum inflammatory biomarker concentrations	Serum concentrations of IL-6, TNF-α, MCP-1, and LBP will be measured individually and reported separately.	Baseline, week 2 and week 12
Breath Biomarkers	Volatile Organic Compounds (VOCs) and exhaled breath condensate (EBC) to assess sulfur-containing metabolites and host-microbiota interactions	Baseline, week 2 and week 12
Adherence to the Elemental Diet and Reduced Sulfur Diet Intervention	Adherence to the ED intervention will be assessed using a modified Medication Adherence Report Scale questionnaire at each visit, as well as through compliance phone calls and food diaries. Poor adherence will be defined as meeting at least one of the following three criteria: intolerance, indicated by discontinuation of dietary therapy due to the patient's refusal to continue; or; low adherence scores (score of 0-1) reported on the modified Medication Adherence Report Scale; and; collect the empty mBiota containers as a measure of adherence. Adherence to the RS diet will be assessed through food recalls collected via ASA-24. Adverse events (AEs) will be systematically collected throughout the study using a combination of participant self-reporting, scheduled assessments, and clinical monitoring.	Baseline, week 2 and week 12
Change in Quality of Life	Health-related quality of life will be measured using the 12-item short form-12 (SF-12). The SF-12 comprises two components: physical health and mental health. Scores range from 0 to 100, where 0 indicates the lowest level of health and 100 the highest.	Baseline, week 2 and week 12
Change in Anxiety	Anxiety will be assessed by the GAD-7 (Generalized Anxiety Disorder-7). It is a self-reported screening tool used to measure the severity of generalized anxiety disorder (GAD) symptoms over the past two weeks. The total score ranges from 0 to 21. A score of 10 or higher typically indicates clinically significant anxiety and suggests the need for further evaluation or intervention..	Baseline, week 2 and week 12
Change in Depression	Depression levels will be assessed by PHQ-8 (Patient Health Questionnaire-8). It is a widely used self-report screening tool for assessing the severity of depressive symptoms over the past two weeks. The total score is the sum of all item responses, ranging from 0 to 24. A score of 10 or higher indicates the presence of clinically significant depressive symptoms and suggests the need for further evaluation or intervention.	Baseline, week 2 and week 12
Change in Weight	Body weight will be measured in kilograms (kg)	Baseline, week 2 and week 12
Change in Body Mass Index (BMI)	BMI will be calculated as weight (kg) divided by height squared (m²).	Baseline, week 2 and week 12

Collaborators and Investigators

• Sponsor: University of British Columbia
• Collaborators: University of Calgary
• Investigators: Principal Investigator: Natasha Haskey, RD, PhD, University of British Columbia

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): March 1, 2029
• Study Completion (Estimated): December 31, 2029

Study Registration Dates

• First Submitted: May 29, 2026
• First Submitted That Met QC Criteria: June 5, 2026
• First Posted (Actual): June 11, 2026

Study Record Updates

• Last Update Posted (Actual): June 11, 2026
• Last Update Submitted That Met QC Criteria: June 5, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Ulcerative colitis
• Additional Relevant MeSH Terms: Intestinal Diseases; Digestive System Diseases; Gastrointestinal Diseases; Colonic Diseases; Gastroenteritis; Inflammatory Bowel Diseases; Colitis; Colitis, Ulcerative
• Other Study ID Numbers: H26-00017; POP25-11968 (Other Grant/Funding Number: Weston Family Foundation)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD used in the results of the publication will be shared
• IPD Sharing Access Criteria: A proposal for planned analyses must be submitted to the PI's of this research.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No