Adding Guar Gum to High-Fat Diets Ameliorates Fish Growth, Gut Histology, Gut Microbiota Composition, and Intestinal Inflammation in Common Carp.

The purpose of this research was to investigate how adding dietary guar gum to high-lipid diets affected the fish growth and gut health of common carp (Cyprinus carpio). A normal-lipid diet (5% crude lipid; control) and four high-lipid diets (10% crude lipid) with 0% (high-fat [HF]), 0.3% (GG0.3), 1% (GG1), and 3% (GG3) of guar gum were developed and fed to fish (4.53 g) for 8 weeks. The findings showed that HF induced impairment of intestinal morphology and mucosal barrier, oxidative stress, gut dysbiosis, and gut inflammation. Compared to the HF, guar gum-containing diets substantially improved gut villus height, upregulated the expression levels of nuclear factor erythroid 2-related factor 2 and zonula occludens-1, and downregulated the expression levels of toll-like receptor 1 (tlr1), tlr5, myeloid differentiation factor 88, interleukin-1β (il-1β), il-6, and il-8. Moreover, the GG0.3 and GG1 diets dramatically increased catalase (cat) and occludin expression levels. Furthermore, the GG1 and GG3 diets improved the microbiota composition by increasing Fusobacteria and Cetobacterium abundance while lowering Proteobacteria, Acidovorax, Acinetobacter, Serratia, and Comamonas abundance. Correlation analysis revealed that guar gum improved gut health by modulating gut microbiota and tight junction proteins. The findings indicated that guar gum can ameliorate HF diet-induced intestinal damage in fish.