Rapeseed protein prevents the initiation of insulin resistance by dietary saturated fat and sucrose in rats

Abstract

The metabolic or insulin-resistance syndrome is experimentally induced by diets rich in saturated fat and sucrose but the influence of the nature of the dietary protein in the diet has been overlooked. We aimed at testing if rapeseed protein, an emergent cysteine-rich source of protein, could inhibit the onset of the metabolic syndrome. For 9 weeks, rats were fed a diet rich in saturated fat and sucrose and including 20% protein either as milk protein (“Induction” diet, I) or rapeseed protein (R diet). A third, control group was fed a isoenergetic diet made of milk protein with polyunsaturated fat and starch (“Prudent” diet, P). Plasma glucose, insulin, triglycerides, cholesterol and blood pressure were followed during the study, glucose tolerance was tested at week 7, and body composition assessed at week 9. Plasma glucose, insulin and triglycerides increased during the experiment and at week 9 insulin was lower in R and P as compared to I (147±42 and 99±14 vs. 224±57 pmol/L). The insulin peak after glucose load was 28–30% lower in R and P than in I, and the insulin sensitivity index (based on glucose and insulin AUCs) was higher in R than in I. Peripheral fat deposition was slightly higher in R than in I. In this model, substituting rapeseed protein for milk protein has preventive effects on the early onset of insulin-resistance, similar to manipulating the nature of the fat and carbohydrates. Source of support: ONIDOL/CETIOM.