NCT07381140Not yet recruiting
Bariatric Surgery and Gut Microbiota Changes Over Time
Longitudinal Evaluation of Gut Microbiota and Fecal Metabolome Following Roux-en-Y Gastric Bypass: Clinical Implications and Identification of Predictive Biomarkers
Source: ClinicalTrials.gov · Last updated 5 Feb 2026
Brief summary (registry, in English)
The goal of this observational study is to learn how bariatric surgery affects gut bacteria and gut-related metabolic products over time in adults with obesity. The study includes adults aged 18 to 65 years who are undergoing Roux-en-Y gastric bypass (RYGB) surgery, as well as adults with obesity treated with diet alone and healthy normal-weight adults. The main questions it aims to answer are: How does bariatric surgery change the composition and diversity of gut bacteria over time? How are these changes related to weight loss and improvement of obesity-related health conditions? Researchers will compare people undergoing bariatric surgery with people with obesity treated with diet alone and with healthy normal-weight individuals to see if surgery leads to specific changes in gut bacteria and stool metabolites that are linked to better clinical outcomes. Participants will: Provide stool samples at scheduled time points over 12 months Provide blood samples and undergo routine clinical assessments Take part in follow-up visits to monitor weight, metabolic health, and gastrointestinal symptoms
- Status (registry)
- Not yet recruiting
- Study type
- Observational
- Enrollment
- 100 (estimated)
- First submitted
- 23 Jan 2026
- Start date
- Apr 2026
- Primary completion date
- Apr 2027
- Lead sponsor
- Azienda Ospedaliera Specializzata in Gastroenterologia Saverio de Bellis
- Diseases
- Obesity
- NCT number
- NCT07381140
What you commit to
- Study type: Observational
- Planned participants: 100
- From Apr 2026 to the primary completion date, Apr 2027
- 1 site in 1 country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Treatment with antibiotics within the last 3 weeks, or probiotics/prebiotics within the last 4-6 weeks, or systemic corticosteroids within the 8 weeks prior to baseline (T0).
- Participation in dietary regimens or calorie restriction programs in the weeks prior to enrollment.
- Previous organ transplant or ongoing systemic immunosuppressive therapy.
- Previous major gastrointestinal surgery.
- Recent gastrointestinal surgery.
- Medications known to influence the gut microbiota (e.g., PPIs, metformin, steroids).
Other illness
- Chronic inflammatory bowel diseases (e.g., Crohn's disease, ulcerative colitis), ongoing enteric infections, or active neoplasms.
- Chronic alcohol consumption above moderate levels or substance use disorder.
Other
- Pregnancy or breastfeeding.
- Use of antibiotics within the last 3 weeks or probiotics/prebiotics within the last 4-6 weeks.
- Pregnancy or breastfeeding.
- Extreme diets or recent dietary changes.
- Recent international travel that could have affected the gut microbiota.
- Active smoking or excessive alcohol consumption.
- Significant gastrointestinal symptoms (chronic diarrhea or constipation).
Who the study is looking for
- Age between 18 and 65 years.
- Adults with a body mass index (BMI) ≥ 35 kg/m² with related comorbidities, or BMI ≥ 40 kg/m², who are candidates for Roux-en-Y gastric bypass (RYGB) surgery only.
- Age between 18 and 65 years.
- Adults with BMI ≥ 30 kg/m² who are candidates for structured dietary treatment.
- Age between 18 and 65 years.
- Normal weight (BMI between 18.5 and 24.9 kg/m²).
- Normal metabolic function: fasting glucose below threshold, normal ALT/AST, no diagnosis of diabetes or metabolic syndrome.
- No chronic gastrointestinal diseases or conditions that could alter the gut microbiota.
Age in the registry: 18 years to 65 years · Sex: All · Accepts healthy volunteers
Sites (1)
Sites in registry order. Pick your city on the disease page to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| Azienda Ospedaliera Specializzata in Gastroenterologia Saverio de Bellis Coordinator of this site? Confirm its status | Castellana Grotte | Italy | Unknown status |
This page is information, not medical advice. Discuss any trial with your doctor.