Effects of Soluble and Insoluble Fibre on Glycolipid Metabolism and Gut Microbiota in High-Fat-Diet-Induced Obese Mice

Abstract

Background: Dietary fibre can alleviate or reduce the risk of obesity and obesity-induced abnormalities in glycolipid metabolism. However, the effects of different types of dietary fibre or their combinations on obesity remain unclear. Here, we explored the effects of different ratios of inulin soluble dietary fibre (ISDF) and barley leaf insoluble dietary fibre (BLIDF) on the body weight, glycolipid metabolism and gut microbiota of obese mice. Methods: Seven experimental groups were treated with different combinations of soluble and insoluble fibre, comprising HFD (high-fat diet without dietary fibre), BLIDF, ISDF, I3S1DF (insoluble/soluble = 3:1), I2S2DF (insoluble/soluble = 1:1), I1S3DF (insoluble/soluble = 1:3) and MIX (inulin, BLIDF and matcha powder fibre; insoluble/soluble = 3.6:1) groups. Results: Our results showed that the BLIDF, ISDF and MIX treatments decreased the body weight gain of the HFD mice significantly after eight-week interventions. All the fibre intervention groups except the MIX group displayed lower fasting blood glucose and glycosylated serum protein levels than the HFD group. BLIDF, ISDF, I3S1DF and I2S2DF improved the glucose tolerance of the mice. Moreover, none of the dietary fibre interventions affected the liver lipid metabolism, while I3S1DF and I1S3DF improved the abnormal serum lipid metabolism. BLIDF, ISDF, I3S1DF and I2S2DF reduced the serum IL-6 levels, and BLIDF and I1S3DF increased SOD activity significantly. Additionally, all the dietary fibre interventions decreased the Firmicutes to Bacteroidota (F/B) ratio and increased the abundance of beneficial gut microbes differently. Conclusions: In short, our results suggest that different ratios of soluble and insoluble dietary fibre have unique impacts on mice body weight, glycolipid metabolism, inflammation and gut microbiota. The ratio of soluble to insoluble dietary fibre intake should be considered for specific health goals in the future.