The purpose of this study is to investigate the effects of a fibre mixture added to a high-protein diet on metabolic, gut and brain health.

The fibre mixture that will be investigated is hypothesized to improved metabolic, gut and brain health. It potentially increases insulin sensitivity, satiety, gut barrier function, improves food-reward related brain activity and decreases inflammation, gut permeability, and ectopic lipid accumulation, among other potential health effects.

The fibre mixture will be administrated during 12 weeks combined a high-protein diet. The placebo-controlled parallel design of the study allows for a placebo group to use maltodextrin combined with a high-protein diet for 12 weeks. The high-protein diet is known to increase satiety and might enhance the difference between the intervention and placebo groups in terms of outcome measurements. The potential health effects as described earlier will be investigated using different techniques.

Inclusion Criteria:

• Age 30-75 years
• Male/female
• BMI 28-40 kg/m2
• Impaired fasting glucose or glucose tolerance, determined using the following criteria (participant should meet at least one criteria):
• HbA1c 42-47 mmol/mol OR fasting glucose (>10h fasted) 5.6-6.9 mmol/l OR Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) >1.85

Exclusion Criteria:

• Diabetes mellitus (type 1 or 2)

• Cardiovascular disease (except hypertension (<160/100mmHg is allowed), pulmonary disease, kidney disease/failure, liver disease/failure

• Gastrointestinal disease or a history of abdominal surgery (except appendectomy and cholecystectomy)

• Diseases affecting glucose and/or lipid metabolism

• Malignancy (except non-invasive skin cancer)

• Auto-immune disease

• Major mental disorders

• Ongoing (infectious) disease or any disease with a life expectancy ≤5 years

• Substance abuse (nicotine abuse (including e-cigarettes) defined as >20 cigarettes per day; alcohol abuse defined as ≥8 drinks/week for females and ≥15 drinks/week for males(38); any drugs)

• A change in weight ≥3kg over the last 3 months or plans to lose weight or follow a hypocaloric diet during the study period

• Pre/pro/antibiotic use in the last 3 months or during the study

• Use of medication that influences glucose or fat metabolism and inflammation, such as:

  • Use of statins (stable use ≥3 months prior to and during study is allowed)
  • Use of antidepressants (stable use ≥3 months prior to and during study is allowed)
  • Use of specific anticoagulants
  • Use of medication known to interfere with study outcomes
  • Use of β-blockers
  • Chronic corticosteroid treatment (>7 consecutive days)

• Regular use of laxatives 3 months prior to the study or during study period

• Change in physical activity or diet during study period

• Intensive physical activity (>3h per week)

• Pregnancy

• Following a vegan or vegetarian diet; presence of food allergies, intolerances or diet restrictions interfering with the study.