Incorporation of whole oat, especially bran, into a high-fat diet, improves cardio-metabolic risk factors in type 2 diabetic rats

Purpose The purpose of this study was to determine the effects of whole oat, oat bran and refined oat incorporation in a high-fat diet (HFD) on cardio-metabolic risk biomarkers in rats with type 2 diabetes mellitus (T2DM). Design/methodology/approach T2DM was induced by feeding male rats with an HFD for 10 weeks, followed by a low dose of streptozotocin. T2DM rats were then divided into four homogeneous groups. Three groups consumed an HFD containing 45 per cent (g/100 g diet) whole oat, oat bran or refined oat. The fourth untreated group (control) received the HFD. Findings The results showed that whole oat and oat bran, compared with refined oat and control, effectively reduced food intake (p < 0.007), arterial blood pressure (p = 0.0001), glycemia (p < 0.001), insulinemia (p < 0.01), glycosylated haemoglobin (p < 0.001) as well as homeostasis insulin resistance (HOMA-IR) (p < 0.001). They also improved blood lipid levels and reverse cholesterol transport by reducing serum total cholesterol (p = 0.0001), triacylglycerols (p < 0.05), very-low- (p = 0.0001) and low-density lipoproteins cholesterol contents (p < 0.02) increasing lipids (p < 0.002) and cholesterol excretion (p = 0.0001), and high-density lipoprotein cholesteryl esters (HDL2-CE) concentrations (p = 0.0001) and stimulating lecithin: cholesterol acyltransferase (LCAT) activity (p = 0.0001). Moreover, they attenuated lipid peroxidation by increasing paraoxonase-1 (PON-1) atheroprotective activity (p < 0.05). Originality/value In T2DM rats, whole oat and particularly, its bran incorporated into an HFD improves arterial blood pressure, glycemic balance and lipid metabolic pathway by reducing hypertriglyceridemia and hypercholesterolemia and increasing atheroprotective activities of LCAT and PON-1. In contrast, refined oat accentuates the risk factors associated with diabetes.