Acute Microbial Switch

In this project the investigators aim to test whether it is possible to precisely measure the changes in fermentation gas patterns after supplementation of a complex fibre mixture over a 36-hour period in both lean normoglycemic and individuals with insulin resistance and/or prediabetes with overweight when compared with a placebo. Additionally, the investigators will investigate whether changes in fermentation patterns will be directly related to changes in carbohydrate and fat oxidation and to microbial composition or related metabolites and hormones in blood, faeces, and urine.

Inclusion criteria

• Lean normoglycemic individuals:
• Lean (BMI ≥ 18.5 kg/m2 and ≤ 24.9 kg/m2 );
• Normal fasting glucose (plasma glucose < 5.6 mmol/L) and a HOMA-IR< 2.2

Individuals with overweight/obesity and prediabetes/insulin resistance:

• Overweight/obesity (BMI ≥ 28 kg/m2 and ≤ 40 kg/m2 );
• insulin resistance (HOMA-IR>2.2) and/or impaired fasting glucose (IFG: plasma glucose ≥ 5.6 mmol/l)

For both subject groups:

• Aged 30 - 75 years;
• Normal blood pressure (systolic blood pressure 100-150mmHg, diastolic blood pressure 60-100 mmHg);
• Weight stable for at least 3 months (± 2 kg)

Exclusion criteria

• T2DM (defined as fasting plasma glucose ≥ 7.0 mmol/L)
• Gastroenterological diseases
• Abdominal surgery affecting the GI tract;
• Cardiovascular diseases, cancer, liver or kidney malfunction, disease with a life expectancy shorter than five years;
• Abuse of products;

• Alcohol (> 15 standard units per week)
• Drugs
• Excessive nicotine use defined as >20 cigarettes per day;
• Plans to lose weight or following of a hypocaloric diet
• Regular supplementation of pre- or probiotic products, use of pre- or probiotics three months prior to the start of the study;
• Intensive exercise training more than three hours a week;
• Use of most medications that influence glucose or fat metabolism, like some lipid lowering-drugs (e.g., PPAR γ or PPARα (fibrates) agonists), glucose-lowering agents (including all sulfonylureas, biguanides, α-glucosidase inhibitors, thiazolidinediones, repaglinide, nateglinide and insulin), inflammation (e.g., anti-inflammatory* or immunosuppressive drugs) and anti-oxidants;
• Regular use of laxatives;
• Use of antibiotics in the last three months (antibiotics use can alter substantially the gut microbiota composition).
• Veganism
• Lactose intolerance
• For women: pregnancy or lactation