The Effect of 6 Weeks Saturated and Polyunsaturated High-Fat Diets on Insulin Sensitivity and Health Parameters

Overview

The aim of the intervention is to gain insight into the long term effect of dietary fatty acid quality on insulin sensitivity and health parameters in healthy men. Whole body and peripheral insulin sensitivity were measured, together with analyses of plasma hormones and metabolites. The plasma proteome was also analyzed. Molecular adaptations in skeletal muscle and adipose tissue were subject for investigation. Furthermore, gut microbiota population number and diversity will be analyzed from faeces samples obtained before and after the intervention.

Two experimental diets with a high fat content (65 E% fat), enriched in either saturated or polyunsaturated fatty acids, were provided for 6 weeks to healthy men, in a randomized controlled intervention study with two arms. Healthy, untrained, non-obese male subjects (27-45 years) were included in the study. The experimental diets are eucaloric, and thus provided so the subjects remains weight stable. Before and after the intervention, two experimental days was conducted (2 experiments before and 2 experiments after the intervention). At pre-intervention, subjects completed a high-fat meal test and insulin sensitivity was measured by the hyperinsulinemic-euglycemic clamp. On both days, blood and tissue biopsies were obtained. These two experimental days were repeated at the end of the 6 weeks intervention. The hyperinsulinemic-euglycemic clamp was combined with stable isotope infusion (deuterium labelled glucose) in order to measure hepatic glucose production. Before the clamp, a catheter is inserted into the femoral vein, to enable measurement of insulin stimulated glucose uptake across the leg. Biopsies are obtained by the needle biopsy method from the vastus lateralis muscle and peri-umbilical subcutaneous adipose tissue. Blood samples were analyzed for glucose, insulin, inflammatory markers, gut hormones, adipokines, plasma fatty acid composition, and lipoprotein profile. Indirect calorimetric was also applied to measure substrate oxidation during the experimental days.