Modified wheat bran insoluble dietary fiber ameliorates lipid metabolism in high fat diet rats

Wheat bran was synergistically fermented using a mixture of probiotic strains that is Lactobacillus plantarum (L. plantarum) and Lactobacillus acidophilus (L. acidophilus) in a 1: 1 ration under the same condition. Insoluble dietary fiber (IDF) was isolated from wheat bran with or without fermentation modification. The changes of physicochemical and functional properties of IDF were measured. The effects of modified wheat bran IDF (C-IDF) on obesity and lipid metabolism in high-fat diet (HFD) rats were also investigated. Results indicated that loose density (LD), tapped bulk density (TBD) of the C-IDF were significantly decreased by 10.81% and 4.03%, respectively, compared to those of U-IDF. While the binding abilities of water and oil, the adsorption capacities of nitrite ion, as well as the cation exchange competence of C-IDF were significantly enhanced (P < 0.05) by 13.43%, 10.19%, and 14.39%, respectively. Compared to the rats in HFD group, the body weight, total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of rats treated with C-IDF were significantly decreased (P < 0.05), while fecal fat content and glutathione (GSH) level of rats in C-IDF group were significantly increased (P < 0.05). The high density lipoprotein cholesterol (HDL-C), and activity of superoxide dismutase (SOD) of rats administrated with C-IDF revealed an upward trend. The mRNA expression levels of hepatic lipid metabolism-related genes (Fasn and Ppara) were significantly up-regulated (P < 0.05). The mRNA expression levels of inflammation related genes (MyD88 and NF-κB) were significantly down-regulated (P < 0.05). The protective effects of C-IDF on the liver and colon were confirmed by simultaneous histological observation. The potential mechanism of C-IDF to prevent from HFD induced obesity and lipid metabolism disorder was carried out through interfering with Fasn/Ppara and TLR4/MyD88/NF-κB signal pathway. Overall, synergistic probiotic fermentation altered the physicochemical and functional properties of wheat bran IDF. The modified IDF suggested potential hyperlipidemic benefits and promising application in healthy food production.