Red raspberry (poly)phenolic extract improves diet-induced obesity, hepatic steatosis and insulin resistance in obese mice

Abstract

BACKGROUND: Red raspberry (Rubus idaeus L.), a natural dietary source of (poly)phenols, has been used as medicine for centuries. OBJECTIVE: The purpose of this study is to determine the effect of a red raspberry (poly)phenolic extract (RPE) on diet-induced obesity, hepatic steatosis and insulin resistance, and elucidate the underlying molecular mechanisms. METHODS: Male specific pathogen-free C57BL/6J mice were randomly divided into three groups (n = 12 per group), and fed with low-fat diet (10% fat energy), high-fat diet (HFD, 45% fat energy), or HFD supplemented with RPE of 150 mg/kg body weight by intragastric administration for 14 weeks. Obesity-related biochemical indexes and hepatic gene expression levels were determined. The statistical analyses were conducted using one-way analysis of variance (ANOVA) followed by Duncan’s multiple range test. RESULTS: The body weight gain, steatosis grade scores and insulin resistance index in the RPE group decreased by 34.48% (P = 0.00), 58.82% (P = 0.00), and 53.77% (P = 0.00), respectively, compared to those in the HFD group. Moreover, RPE supplement significantly changed the expression profile of the genes involved in lipid metabolism and fibroblast growth factor 21 signaling pathway. CONCLUSIONS: This study demonstrated that RPE protected from diet-induced obesity and related metabolic disorders by improving the lipid metabolism and fibroblast growth factor 21 resistance.