Abstract: Undigested components from a large intake of red meat can be fermented by the intestinal flora to form harmful metabolites, thereby destroying intestinal homeostasis and increasing the risk of colon cancer and cardiovascular diseases. To explore the effect of dietary addition of inulin or soybean dietary fiber (SDF) on the intestinal flora and metabolites in mice fed a beef-containing diet, male C57BL/6Cnc mice were randomly divided into a blank control group, a beef group, a beef plus inulin group, and a beef plus SDF group. The intestinal flora structure of mice was detected by high-throughput 16S rRNA gene sequencing. The concentrations of short-chain fatty acids (SCFAs) in the colon contents were detected by gas chromatography-mass spectrometry (GC-MS), and the content of trimethylamine oxide (TMAO) in the kidney was determined. The results showed that in the beef group, the diversity of intestinal flora decreased significantly (P < 0.05), the abundance of Firmicutes, Lactobacillus and Clostridium_sensu_stricto_1 increased, and the abundance of beneficial bacteria such as Bifidobacterium and Faecalibaculum decreased; the contents of SCFAs in the colon contents decreased, and the content of TMAO increased significantly (P < 0.05). Dietary addition of inulin or SDF significantly improved the diversity of intestinal flora in mice (P < 0.05); inulin increased the abundance of Bifidobacterium and Ruminococcaceae_UCG_014, while SDF increased the abundance of Akkermansia and Faecalibaculum. Both dietary fibers increased the content of SCFAs in the colon contents and decreased the concentration of TMAO in the kidney (P < 0.05). In conclusion, beef intake does have a negative impact on the intestinal flora and metabolites in mice, and this effect can be blocked by addition of dietary fiber to the diet, thereby reducing the risk of various related diseases. These results can provide a theoretical and scientific basis for the development of a reasonable diet and personalized precise nutrition in the future.

Key words: beef; inulin; soybean dietary fiber; intestinal flora; short-chain fatty acid; trimethylamine oxide