Effect of changing the amount and type of fat and carbohydrate on insulin sensitivity and cardiovascular risk: the RISCK (Reading, Imperial, Surrey, Cambridge, and Kings) trial.

Description

This study was conducted to investigate whether replacing saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs) or cabohydrates of high glycemic index (HGI) with low glycemic index (LGI) would improve insulin sensitivity (Si) and other cardiovascular disease (CVD) risk factors in subjects at risk of developing metabolic syndrome. This multicentre, randomized, controlled trial [RISCK (Reading, Imperial, Surrey, Cambridge, and Kings)] included men and women (age range: 30-70 years) from the general population without preexisting CVD or type 2 diabetes, but with 2 or 3 components of the metabolic syndrome. Subjects went through an initial run-in period of 4 weeks with a high-SFA and HGI reference diet and then were randomly assigned to 5 intervention diets: high-SFA and HGI (reference), high-MUFA and HGI (HM/HGI), HM and low-GI (HM/LGI), low-fat and HGI (LF/HGI), and LF and LGI (LF/LGI) diets that lasted 24 weeks. A total of 548 subjects were analyzed and results showed no significant effect of the dietary interventions on Si. However, total cholesterol, LDL cholesterol and apolipoprotein B concentrations decreased with SFA reduction. Moreover, lowering GI enhanced the reduction in total cholesterol and LDL cholesterol concentrations. HDL cholesterol and apolipoprotein AI concentrations were also lowered with fat reduction. These findings suggest that the type and nature of fat and carbohydrates do not appear to affect insulin sensitivity, but do improve the lipid profile.