Cod and soy proteins compared with casein improve glucose tolerance and insulin sensitivity in rats

1 Department of Food Science and Nutrition, Human Nutrition Research Group, 3 Department of Anatomy and Physiology, Laval University, Ste-Foy, Québec G1K 7P4; and 2 Lipid Research Centre, Laval University, Ste-Foy, Québec, Canada, G1V 4G2 The aim of the present study was to determine the effects of feeding various dietary proteins on insulin sensitivity and glucose tolerance in rats. Male Wistar rats were fed for 28 days with isoenergetic diets containing either casein, soy protein, or cod protein. Cod protein-fed and soy protein-fed rats had lower fasting plasma glucose and insulin concentrations compared with casein-fed animals. After intravenous glucose bolus, cod protein- and soy protein-fed rats induced lower incremental areas under glucose curves compared with casein-fed animals. Improved peripheral insulin sensitivity was confirmed by higher glucose disposal rates in cod protein- and soy protein-fed rats (15.2 ± 0.3 and 13.9 ± 0.6 mg · kg 1 · min 1 , respectively) compared with casein-fed animals (6.5 ± 0.7 mg · kg 1 · min 1 , P