Clinical trial NCT06802276: Smart Underwear to Measure Diet-Induced Hydrogen Sulfide Production
Official title: Employing Smart Underwear to Measure Gut Microbial Hydrogen Sulfide Production
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: NA
Conditions: Hydrogen Sulfide
Gastrointestinal Microbiome
Keywords: Hydrogen Sulfide
H2S
Diet
Cysteine
Gut Microbiome
Lead sponsor: University of Colorado, Denver
Sponsor class: OTHER
Collaborators: name: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
name: University of Maryland, College Park
First posted: 2025-01-31
Enrollment: 25
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: The study design is a two-period crossover feeding study, in which participants will be randomly assigned to each of a high cysteine and low cysteine isocaloric diet for a 6-day period each. Additionally, a 3-day baseline period will occur prior to each dietary intervention period. Diet intervention periods will be separated by a washout period. This washout period may vary slightly between participants and will last for a minimum of 9 days and a maximum of 13 days.
Primary purpose: OTHER

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.

Detailed description: H₂S is a circulating signaling molecule that plays numerous roles in human physiology. H₂S produced exogenously by the gut microbiota influences human health by modulating systemic H₂S bioavailability in a diet-dependent manner. Several lines of evidence suggest excessive gut microbial H₂S production may be etiologically involved in a wide range of diseases, from colorectal cancer to ulcerative colitis. However, research on the health-relevant effects of gut microbially-produced H₂S has been constrained by technical limitations.

Gap: Current techniques for measuring gut microbial H₂S production are imprecise, invasive, and have limited temporal resolution, hindering the ability to deconvolute how gut microbial H₂S production both affects human health and is influenced by factors such as diet. Gaseous rectal effluent (flatus) is an ideal, yet untapped biospecimen to measure gut microbial H₂S production.

Preliminary Evidence: To enable real time measurements of gut microbial H₂S production in flatus, the investigators are developing a wearable device called "Smart Underwear". The Smart Underwear device is fundamentally different from previous methods used to measure gut microbial H₂S production. The Smart Underwear device uses an array of metal oxide gas sensors coupled with a multi-layer filtration system to selectively measure H₂S by comparing the signal from filtered and unfiltered sensors. The Smart Underwear sensor array is adhered to the outside of a participant's underwear adjacent to the perineum. Through in vitro and human wearing validation, the investigators have demonstrated the feasibility of the Smart Underwear v1 prototype to measure gut microbial H₂S production in flatus and have shown that the device has potential utility in human cohort studies as a non-invasive device.

The long-term goal of this study is to develop a validated Smart Underwear device that measures real time gut microbial hydrogen sulfide (H₂S) production which is responsive to dietary changes and capable of predicting of pathophysiological outcomes.

The investigators will validate the Smart Underwear prototype device using structured dietary modulation of H₂S production.

Aim: Conduct a randomized controlled feeding trial to evaluate the ability of the Smart Underwear device to quantify diet-induced changes in gut microbial H₂S production.

Hypothesis: The investigators hypothesize that the Smart Underwear device will detect higher H₂S concentrations in flatus during a high cysteine dietary intervention compared to a low cysteine dietary intervention.

Methods: The investigators will employ a randomized crossover feeding trial with two arms designed to contrast gut microbial H₂S production by modulating dietary cysteine while controlling other dietary factors (total calories and nutrients). The investigators have conducted extensive background research to determine that modulation of dietary cysteine is the most effective means of producing a diet-induced contrast in H₂S production. Participants will wear the Smart Underwear device during the dietary interventions allowing for a rigorous evaluation of the devices ability to detect diet-induced alterations of gut microbial H₂S production in flatus.

Eligibility criteria: 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

Primary outcomes:
measure: Hydrogen sulfide (H2S)
timeFrame: Daily for 6 days during each dietary intervention period (total of 12 days).
Secondary outcomes:
measure: Microbiome Activity Index
timeFrame: Daily for 6 days during each dietary intervention period (total of 12 days).
measure: Gastrointestinal Microbiome
timeFrame: The final day of each 6-day dietary intervention period (total of 2 days).
measure: Experienced Symptoms Questionnaire
timeFrame: The final day of each 6-day dietary intervention period (total of 2 days).
measure: Participant Wearing Time
timeFrame: Daily for 6 days during each dietary intervention period (total of 12 days).
measure: Systolic Blood Pressure (SBP)
timeFrame: The final day of each 6-day dietary intervention period (total of 2 days).
Other outcomes:
Locations:
city: Aurora
country: United States
facility: University of Colorado Anschutz Medical Campus
state: Colorado
Study officials:
affiliation: University of Colorado, Denver
name: Noel T Mueller, PhD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Maryland, College Park
name: Andrew B Hall, PhD
role: PRINCIPAL_INVESTIGATOR
References: