Organic versus conventional fruits and vegetables: effects on the gut microbiome and metabolic health
MicroHealth Project: Human Trial A A Randomized Comparative Trial to Examine the Impact of Organically vs Conventionally Grown Crops on the Human Gut Microbiome and Health
This trial will test whether eating organic versus conventional fruits and vegetables for 4 weeks changes gut bacteria and glucose metabolism in adults with normal weight or with obesity and early metabolic syndrome.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 44 (estimated) |
| Ages | 18 Years to 45 Years |
| Sex | All |
| Sponsor | Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA) Academic / other |
| Locations | 1 site (Amsterdam, Amsterdam) |
| Trial ID | NCT07165145 on ClinicalTrials.gov |
What this trial studies
This is a double‑blind, randomized, parallel dietary intervention in 40 adults conducted at Amsterdam UMC where participants receive weekly meal kits built around either organic or conventional fruits and vegetables for 4 weeks. The study compares gut microbiome composition and function, glucose metabolism measures, short‑chain fatty acids in plasma and feces, pesticide residues, blood and breath metabolomics, and changes in weight and body composition. Participants include healthy adults (BMI 19–25) and drug‑naïve adults with BMI 28–40 and at least three components of metabolic syndrome. Stool, blood, and breath samples are collected before and after the intervention to link crop cultivation practices to microbiome and cardiometabolic outcomes.
Who should consider this trial
Good fit: Adults aged 18–45 who are Caucasian and either have a BMI of 19–25 with no medical conditions or a BMI of 28–40 with drug‑naïve metabolic syndrome (three components) are the intended participants.
Not a fit: People currently using antibiotics, following restrictive diets (vegan, strict organic, or vegetarian), with severe food allergies, or who fall outside the age/BMI ranges are unlikely to benefit or may be ineligible.
Why it matters
Potential benefit: If successful, this could show that choosing organic versus conventional produce changes gut bacteria and improves glucose control, offering a simple dietary approach to reduce metabolic risk.
How similar studies have performed: While many studies link overall diet to the gut microbiome and metabolic health, the specific impact of microbes and residues from organic versus conventional produce is relatively novel and not well established.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * 22 Healthy Volunteers : healthy Caucasian adults with a BMI \< 25 kg/m\^2 will be recruited with no medical conditions. * 22 Metabolically Impaired Participants: Caucasian adults with a BMI ranging from 28 kg/m\^2 to 40 kg/m\^2 with three components of Metabolic Syndrome, drug-naïve: * Elevated waist circumference (WC): with men having WC \> 102 cm (40 inches) and women having a WC \> 88 cm (35 inches). * High Fasting Plasma Glucose (FPG): a fasting plasma glucose level 110 mg/dL (6.1 mmol/L) * High Fasting Plasma Insulin (FPI): A fasting insulin level ≥25 μU/mL (or \>16.7 pmol/L) * HOMA-IR score of ≥2.5 Exclusion Criteria: * Use of antibiotic in the past 3 months or currently taking them * Past/ Currently following a vegan, strictly organic or vegetarian diet. * History of severe food allergies or intolerances that would render it unsafe for them to consume any of the fruits and vegetables provided. Exclusion will be determined on a case-by-case basis by the investigator. * Inability or unwillingness to collect stools. * Presence of overt type 1 diabetes mellitus (T1DM) and/or type 2 diabetes. * Use of medications for type 2 diabetes: metformin, statin, proton pump inhibitors (PPI), H2 blockers, pioglitazone, active GLP-1 receptor agonists (e.g., exenatide, liraglutide). * Prior or planned bariatric surgery, history of cholecystectomy. * History of cardiovascular disease, having a severe disease of the digestive tract, such as celiac disease, Crohn's disease, active ulcerative colitis. * Surgery scheduled for the trial duration period. * Pregnant or nursing women. * Smoking or illicit drug use. Use of \>5 units of alcohol daily on average. * History of neurological/neurodegenerative disorders. * Participation in another concomitant clinical trial. * Not residing in the Netherlands during study period (Sept-Nov 2025)
Where this trial is running
Amsterdam, Amsterdam
- Amsterdam UMC, locatie AMC — Amsterdam, Amsterdam, Netherlands (Recruiting)
Study contacts
- Principal investigator: Max Nieuwdorp, Dr. Prof. — Dept of Vascular Medicine, Amsterdam UMC - AMC
- Study coordinator: Max Nieuwdorp, Prof., Dr.
- Email: m.nieuwdorp@amsterdamumc.nl
- Phone: 020-5665737
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.