The overall aim is to investigate effects of saturated versus polyunsaturated fat on glycemic regulation and satiety in a postprandial study with healthy individuals. The potential effects will be related to changes in gut microbiota, the circulating levels of short chain fatty acids, inflammation and gene expression in peripheral mononuclear blood cells.

The intervention study will have a randomized, double blinded, cross-over design with different test meals consisting of saturated or polyunsaturated fat. The amount of fat will be identical in the test meals, but the fat quality will vary. The test meals are in the form of muffin and spread.

All participants will consume two muffins and minimum 20 g of spread a day for three consecutive days, consisting of either a high proportion of saturated fat or a high proportion of polyunsaturated fat. At day one (visit 1 and 3) and day four (visit 2 and 4) of the intervention week, the participants will perform a postprandial glucose test (OGTT, 75 g glucose in 100 ml water) at Oslo Metropolitan University. Blood samples will be taken before and at different time points after the glucose test. One week prior to the intervention week and during "wash-out" (11 days), the participants will consume the control products which are high in saturated fat.

At the screening visit (visit 0) the participants will be asked to limit the intake of dietary fat and fiber from oat and barley one week prior to visit 1 and during the study. Otherwise, participants will be asked not to change their diet and exercise habits during the study period. Individuals fulfilling the inclusion criteria will also be invited to participate in a cross-sectional study for investigating the gut microbiota in a healthy population.

An OGTT will be performed at visit 1, 2, 3 and 4.

The participants will receive test meals after screening and before visit 1, 2, and 3.

Inclusion Criteria:

• BMI between 18,5 and 27 kg/m2
• Fasting plasma glucose ≤ 6.1 mmol/l

Exclusion Criteria:

• Chronic metabolic diseases such as diabetes type 1 and 2, coronary heart disease and cancer the last 6 months.
• Intestinal diseases such as chron's disease, ulcerative colitis and irritable bowel syndrome.
• Food allergy and intolerances towards grain and dairy products.
• Pregnant and lactating
• Smokers
• Fasting blood glucose ≥ 6.1 mmol/L
• BMI <18,5 and >27 kg/m2
• Planned weight reduction and or ± 5% weight change over the past three months.
• Use of antibiotics last 3 months before study entry and during the study period
• Use of probiotics the last month before study entry and during the study period
• Blood donor last 2 months before study entry and or during the study period
• Not willing to end the use of dietary supplements, including probiotic products, fish oil etc. four weeks prior to study entry and throughout the study period
• Alcohol consumption > 40g / day
• Hormone treatments (except contraceptives)