Recruiting

Observational Study

Sponsor:

University of Colorado, Denver

Code:

NCT06802276

Conditions

Hydrogen Sulfide

Gastrointestinal Microbiome

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Interventions

High Cysteine Diet

Low Cysteine Diet

Study Details

Brief summary:

The purpose of this study is to evaluate the ability of a wearable Smart Underwear prototype device to quantify diet-induced changes in gut microbial hydrogen sulfide (H₂S) production. The core design is a single-site, 2-period, crossover feeding study with 6-day diet periods and an approximately 11-day washout period. Participants are fed each of two isocaloric diets designed to contrast gut microbial H₂S production (i.e., a high cysteine vs. low cysteine diet), in a random order.

Conditions

Hydrogen Sulfide

Gastrointestinal Microbiome

Study ID

NCT06802276

Start date

May 21, 2025

Status verified date

Apr, 2026

Completion date

Jun 30, 2027

Anticipated

Primary completion date

Jun 1, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

The inclusion/exclusion criteria will identify generally healthy volunteers that are able to ingest the intervention diets. Exclusion criteria based on diseases, medications, allergies, and specific dietary requirements will minimize the risks of adverse reactions to the intervention diets.

Inclusion Criteria:

  • Generally healthy volunteers defined as having no major known health conditions (e.g., diabetes, cancer, hypertension, etc.).
  • Normal bowel movements, with approximately 1 bowel movement reported per day
  • Willing to discuss flatus
  • Ages >18yrs
  • Willing to complete the entire study protocol, i.e. eating all of the food that is provided and completing all required measurements.

Exclusion Criteria:

  • Self-report or other evidence of diabetes, other endocrine/metabolic abnormality, dyslipidemia, morbid obesity, severe hypertension, chronic kidney disease, liver disease, pulmonary disease, gastrointestinal, and cardiovascular diseases
  • Chronic medications for any of the above conditions
  • Food allergy that interferes with ability to complete the study
  • Food preferences, intolerance, or dietary requirements that would interfere with diet adherence
  • Planned dietary changes during the study period
  • Lack of appropriate food refrigeration and preparation equipment (e.g.- oven or microwave)
  • Pregnancy or planned pregnancy in the next month
  • Physical measurements: BMI > 35 kg/m2

Study Design

Enrollment

25 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Other

Interventions and Outcome Measures

Arms

active comparator: High Cysteine Diet

A dietary pattern designed to have a high level of dietary cysteine

other: Low Cysteine Diet

A dietary pattern designed to have a low level of dietary cysteine

Interventions

High Cysteine Diet

A healthy diet pattern which contains high levels of cysteine or cysteine-related compounds. The high and low cysteine diets will be designed by a research dietician to differ primarily in their concentration of cysteine while providing similar levels of calories, protein, fats, carbohydrates, fiber, and several micronutrients. No additional supplementation of cysteine will be used. Examples of high cysteine foods: chicken, eggs, lentils, yogurt, garlic, cheese, soybeans

Low Cysteine Diet

A healthy diet pattern which contains low levels of cysteine or cysteine-related compounds. The high and low cysteine diets will be designed by a research dietician to differ primarily in their concentration of cysteine while providing similar levels of calories, protein, fats, carbohydrates, fiber, and several micronutrients. The low cysteine diet includes lower-protein food sources. Examples of low cysteine foods: rice, bread, oranges, bananas, lettuce, snow peas, peppers

Primary outcome measure

  • Hydrogen sulfide (H2S) [ Time Frame: Daily for 6 days during each dietary intervention period (total of 12 days). ]

Central Contacts and Locations

Central contacts

Noel T Mueller, PhD

414-779-1167noel.mueller@cuanschutz.edu

Locations

University of Colorado Anschutz Medical Campus

Recruiting

Aurora, Colorado, United States, 80045

Contacts

Devin Grove, BS

303-724-1179devin.grove@cuanschutz.edu

More Information

Sponsor

University of Colorado, Denver

Last update posted

Apr 29, 2026

Last verified

Apr, 2026

Keywords

  • Hydrogen Sulfide
  • H2S
  • Diet
  • Cysteine
  • Gut Microbiome

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Colorado, Denver on 2026-04-29.