Clinical trial NCT06932666: Why Calories Are Not the Same - a Gut Explanation?
Official title: Why Calories Are Not the Same - a Gut Explanation
Study type: INTERVENTIONAL
Overall status: NOT_YET_RECRUITING
Phase: NA
Conditions: Diet, Healthy
Breath Analysis
Keywords: Fecal energy
Metabolizable energy
Breath methane
Gut microbiome
Metabolomics
Dietary fiber
Resistant starch
Food particle size
Lead sponsor: University of Copenhagen
Sponsor class: OTHER
Collaborators: name: Wageningen University and Research
First posted: 2025-04-17
Enrollment: 60
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: NON_RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: Overall, there are two parallel arms - high- (HMP) and low- (LMP) methane producers, to which the participants are allocated in a ratio 1:1 after a 4-day screening period, where individual levels of methane in exhaled breath are measured multiple times.

In both arms, participants undergo two 3-days dietary interventions in a crossover design and separated by a +10-day washout period. Participants are randomized to receiving diet A first or diet B first. These two diets are isocaloric and equal in macronutrient composition, but differ on dietary fiber, resistant starch and food particle size.
Primary purpose: BASIC_SCIENCE

Brief summary: The aim of this study is to understand how the gut microbiome influences how much dietary energy humans excrete via feces. This study is based on the hypothesis that levels of methane in exhaled breath represent two different gut microbiome community structures, and therefore influence fecal energy excretion differently. Moreover, this study is assessed in the context of two different diets, both isocaloric and equal in macronutrient composition, but differing in contents of fiber, resistant starch, and large particles; which are hypothesized to impact the gut microbiome differently.

Detailed description: The trial is a cross-over trial including two controlled isocaloric dietary interventions of three days duration. The two diets are isocaloric but with different contents of fiber, resistant starch, and food particle sizes. Each intervention is separated by a wash-out period of at least 10 days where participants adhere to their habitual diet. The trial includes a total of five visits (one screening visit and four regular visits).

Before the trial, participants undergo a screening period of 4 days. During the 4-day screening period, participants measure the levels of methane in their exhaled breath. Based on median breath methane levels, participants are allocated to one of the two arms: (HMP: high methane producers; LMP: low methane producers). Enrollment in the intervention trial will be conducted so there are similar numbers of participants in both arms.

At the beginning and at the end of each 3-day intervention period, participants consume a blue muffin, containing a royal blue dye that changes the stool color. The appearance of the color in stool following the first muffin will mark the beginning of the stool collection period, which will continue until the stool color change is no longer noticeable following consumption of the second muffin. Therefore, the duration of the stool collection period, which is estimated to be on average 3 days, will ultimately depend on the participants' passage time of food (i.e., intestinal transit time).

During the screening period, participants are asked to:

* measure their methane and hydrogen levels in exhaled breath using a portable device
* report defecation patterns (including stool frequency and Bristol Stool Scale)

Before each intervention period, participants are asked to:

* collect a fecal and urine sample
* register three days of habitual diet

At the visits before each intervention period, the following samples are collected:

* a blood sample
* methane and hydrogen measurements in exhaled breath
* anthropometrics
* data on physical activity

During the intervention periods, participants are asked to:

* exclusively eat all the foods provided
* collect all their stool samples, as specified above
* collect three morning urine samples (one daily for the following three days)
* measure their methane and hydrogen levels in their exhaled breath using a portable device
* report their defecation patterns and gastrointestinal symptoms

Eligibility criteria: Inclusion Criteria:

* 18-65 years old
* BMI:18.5-29.9 kg/m2
* Self-reported regular defecations defined as at least every second day
* Willing to collect urine and stool samples at home and able to temporarily store them in their own freezer in a provided container
* Willing to exclusively eat the food provided
* Owning a smartphone (iOS 11.0 and onwards, or Android 5.0 and onwards) with access to the internet
* Speak and understand Danish or English

Exclusion Criteria:

* Current pregnancy or lactation
* Following a specific dietary program or diet (e.g., vegetarian, vegan, gluten-free) or unable to consume the food provided
* Diagnosis of small intestinal bacterial overgrowth (SIBO), inflammatory bowel diseases (IBD), gastrointestinal obstruction, or ischemic colitis
* Diagnosed chronic constipation
* Regular use of diarrhea inhibitors or laxatives
* Any chronic disease that can affect the outcomes of the study
* Use of medications potentially altering gastric pH (proton pump inhibitors, histamine receptor antagonists, antacids)
* Use of medications potentially altering the gastro-intestinal motility (prokinetics, antiemetic agents, anticholinergic agents, narcotic analgesics, nonsteroidal anti-inflammatory drugs, peroral glucocorticoids, and GLP-1 related medications such as semaglutide and liraglutide)
* Use of antibiotics, or any medication that can affect any outcomes of the study, within the previous three months
* Concurrent participation in another trial
* Any condition that makes the project responsible and/or the clinical responsible doubt the feasibility of the volunteer's participation

Primary outcomes:
measure: Total fecal energy excretion (between high- and low-methane producers)
timeFrame: During each stool collection period (following each 3-day intervention period)
Secondary outcomes:
measure: Total fecal energy excretion (between diet A and diet B)
timeFrame: During each stool collection period (following each 3-day intervention period)
measure: Fecal energy density
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Breath hydrogen and methane levels
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Whole-gut transit time
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Stool consistency
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Stool frequency
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Stool moisture
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal pH
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal microbial load
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal host DNA concentration
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal short-chain fatty acids
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Gut microbiome composition (16S)
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Gut microbiome composition and functions (shotgun sequencing)
timeFrame: During each 3-day intervention period and its following stool collection period
Other outcomes:
measure: Gut microbiome-derived metabolites (fecal samples)
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Gut microbiome-derived metabolites (urine samples)
timeFrame: Before and during each 3-day intervention period
measure: Gut microbiome-derived metabolites (blood samples)
timeFrame: Right before each 3-day intervention period
measure: Fecal metabolome (untargeted metabolomics)
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Urine metabolome (untargeted metabolomics)
timeFrame: Before and during each 3-day intervention period
measure: Blood metabolome (untargeted metabolomics)
timeFrame: Right before each 3-day intervention period
measure: Gastrointestinal symptoms
timeFrame: During each 3-day intervention period
measure: Habitual diet records
timeFrame: Right before each 3-day intervention period
measure: Habitual physical activity records
timeFrame: Baseline (before the first 3-day intervention period)
measure: Body weight
timeFrame: Right before each 3-day intervention period
measure: Body fat composition
timeFrame: Baseline (before the first 3-day intervention period)
measure: Muscle composition
timeFrame: Baseline (before the first 3-day intervention period)
measure: Bone composition
timeFrame: Baseline (before the first 3-day intervention period)
measure: Biomarkers of food intake (fecal samples)
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Biomarkers of food intake (urine samples)
timeFrame: Before and during each 3-day intervention period
measure: Biomarkers of food intake (blood samples)
timeFrame: Right before each 3-day intervention period
measure: Fecal particle size
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal carbon-to-nitrogen ratio
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal redox potential
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal biomarkers of inflammation: calprotectin
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Fecal biomarkers of intestinal permeability: zonulin
timeFrame: During each 3-day intervention period and its following stool collection period
measure: Blood markers of glucose metabolism
timeFrame: Right before each 3-day intervention period
measure: Blood markers of lipid metabolism
timeFrame: Right before each 3-day intervention period
measure: Blood markers of inflammation
timeFrame: Right before each 3-day intervention period
measure: Blood markers of appetite
timeFrame: Right before each 3-day intervention period
measure: Blood markers of intestinal permeability: LBP
timeFrame: Right before each 3-day intervention period
Locations:
city: Frederiksberg C
country: Denmark
facility: University of Copenhagen, Department of Nutrition, Exercise and Sports
state: Capital Region
Study officials:
References: