Oat bran β-glucan improves glucose homeostasis in mice fed on a high-fat diet

Oat-based functional foods are commonly produced with 1,3-β- d -glucan-enriched oat bran in which β-glucan (termed as oat bran β-glucan (OB-β-glucan)) not only co-exists with multiple other food components but also exists in different physical forms compared to extracted β-glucan. In the current study, the impacts of OB-β-glucan on the glucose homeostasis of mice fed on a high-fat diet were investigated to determine whether oat bran provided additional functional metabolic effects compared to extracted β-glucan. The experimental results using a C57BL/6J mouse model showed that high-fat (HF) diet treatment significantly increased the body weight (25.1%), fasting blood glucose (17.4%), glycated hemoglobin (HbA1c) (31.6%) and insulin resistance when compared to mice fed on a low fat diet (LF) after treatment for six weeks. In contrast, both OB-β-glucan and its extracted counterpart with the same amount of β-glucan (4%) in the HF-diet significantly improved the insulin sensitivity with reduced levels of HbA1c and body weight gain. The activation of liver glucokinase (GK) and intestinal phosphoenolpyruvate carboxykinase (PEPCK), and an increased ratio of neuro-peptide proopiomelanocortin (POMC) to neuropeptide Y (NPY) suggest a gut-liver-brain axis mechanism to improved insulin sensitivity and glucose homeostasis after treatment by either OB-β-glucan or its extracted counterpart. In conclusion, OB-β-glucan, even in a different physical form, exerted similar physiological effects compared to extracted β-glucan, and the β-glucan is the predominant functional component in the health effects of oat bran on glucose homeostasis. The changes of body weight (A) and food intake (B) of mice fed on different diets of low-fat (LF), high-fat (HF), HF + grain form β-glucan (HFGF), and HF + extracted β-glucan (HFEX).