The Effect of Prebiotics on Gastrointestinal Functioning and Metabolism

A human dietary intervention study will be performed in overweight to obese subjects with a slow gastrointestinal transit time comparing the effects of a soluble prebiotic fibre vs. placebo on gut health, including gut microbiota composition, gastrointestinal transit time, metabolic health and quality of life.

Inclusion criteria

• Overweight to obese men and women (BMI ≥ 25 kg/m2 <35 kg/m2)
• Aged 20-50 years
• Caucasian
• Normal fasting glucose (<6.1 mmol/L.)
• Normal blood pressure (systolic blood pressure 100-140 mmHg, diastolic blood pressure 60-90 mmHg)
• Weight stable in last 3 months (±2 kg)
• A low defecation frequency, <4 times/week and no constipation or underlying pathology, as determined by gastro-intestinal questionnaires).
• A slow whole gut transit (>35h)

Exclusion criteria

• Woman lactating, pregnant (where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive hCG laboratory test) or (post)-menopausal
• Regular smokers
• People with intensive fitness training, eg. athletes (≥3 per week ≥ 1 hour training)
• Diabetes Mellitus (defined as FPG ≥ 7.0 mmol/l and or 2h PG ≥ 11.1 mmol/l)
• Gastro-intestinal diseases or abdominal surgery, cardiovascular diseases, cancer, liver or kidney malfunctioning (determined based on ALAT and creatinine levels, respectively) disease with a life expectation shorter than 5 years
• Following a hypocaloric diet
• Gluten intolerance
• Regular use of laxation products, or use of antibiotics, probiotics or prebiotics 3 months prior to the start of the study
• More than 2 symptoms occurring over a period of 12 weeks in the preceding 12 months such as

• Straining in >1/4 defecations;
• Lumpy or hard stools in >1/4 defecations;
• Sensation of incomplete evacuation in >1/4 defecations;
• Sensation of anorectal obstruction/blockade in >1/4 defecations
• Manual maneuvers to facilitate >1/4 defecations (e.g., digital evacuation, support of the pelvic floor); and/or
• <3 defecations/week
• Current use of medication interfering with study intervention or interfering with study endpoints/hypotheses
• Not to be able to understand the study information
• Blood donation 2 months prior to the study and during the study
• Participation in other studies