Effects of Parboiled Immature Rice Starch (Oryza sativa L.) on Glucose and Lipid Metabolisms in High Fat Diet-induced Obese Mice

Abstract

Metabolic disorders, driven by the overconsumption of simple carbohydrates in processed foods, pose significant global health challenges. Immature rice (Oryza sativa L.), rich in beneficial phytochemicals, has garnered considerable dietary interest, especially through parboiling. This widely utilized technique transforms the physicochemical properties of simple carbohydrate into resistant starch, which is hypothesized to enhance its health-promoting effects. Therefore, this research examined the effects of parboiled immature rice starch (PIRS) on glucose and lipid metabolisms in high fat (HF) diet-induced obese mice. Male MLAC: ICR mice were randomly divided into 3 groups of 5 animals each. The first group was fed with a basic diet (10% of energy from fat), the second group and the third group were each fed with a high-energy lard-based fat diet (45% of energy from fat) that was supplemented with conventional (rapid-release cornstarch) -HF or PIRS-HF diet for 90 days, respectively. The result revealed that PIRS had a mild effect on weight control and body fat deposit (P>0.05) while significantly elevated HDL-c level (P<0.05). PIRS significantly suppressed blood glucose and insulin levels, which thereby lowered HOMA-IR index as compared to the conventional-HF diet group (P<0.05). PIRS demonstrated a preventive effect against hepatic stenosis, as indicated by GGT levels and histological appearances of hepatocytes that were comparable to those of mice fed a basic diet. The result of this study suggested that PIRS may be a valuable alternative carbohydrate source for those who are attempting to control blood glucose level and reducing insulin resistance.