Supplementation of Inulin with Various Degree of Polymerization Ameliorates Liver Injury and Gut Microbiota Dysbiosis in High Fat-Fed Obese Mice.

The chain length of fructan determines its different physiological effects. This study is to explore the effects of low-performance inulin [LPI, degree of polymerization (DP) ≤ 9] and high-performance inulin (HPI, DP ≥ 23) on obesity-associated liver injury of high-fat diet (HFD) feeding mice and its underlying mechanism. Eight weeks of supplementation of C57BL/6J mice with HPI, relative to LPI (p < 0.05), caused the more efficient improvement against the HFD-induced liver insulin resistance through activating IRS1/PI3K/Akt pathway and reduced protein expressions of inflammatory factors nuclear factor-kappaB (NF-κB) and interleukin-6 (IL-6) in the liver. HPI exhibited the more positive effects on liver steatosis by inhibiting acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and sterol regulatory element binding protein 1 (SREBP1) in comparison with LPI (p < 0.05). HPI also increased acetic acid, propionic acid, and butyric acid levels in the colon of HFD-fed mice (p < 0.05). Compared to LPI, HPI feeding of HFD-fed mice led to the more effective decrease in the Firmicutes abundance from 72.1% to 34.5%, but a more significant increase in the Bacteroidetes population from 19.8 to 57.1% at the phyla level, and increased the abundance of Barnesiella, Bacteroides, and Parabacteroides at the genus level (p < 0.05). Depending on DP, HPI exerts the more positive regulation on liver injury and gut microbiota dysfunction than LPI.