Brassica rapa L. Polysaccharides Alleviate T2D via Modulation of Gut Microbiota and Metabolites

The present research sought to investigate the impacts of <i>Brassica rapa</i> L. polysaccharide (Brp) on glycolipid metabolism in diabetic rats and the regulatory role of gut microbiota in metabolic balance. After 30-day Brp gavage, glycolipid metabolic parameters and amino acid levels were measured, and gut microbial communities were sequenced and analyzed. The results showed that Brp improved glycolipid metabolism, alleviated insulin resistance and hepatic oxidative stress, increased liver glycogen synthesis, and modulated gut microbiota composition. Specifically, Brp potentially enhanced short-chain fatty acid (SCFAs) production by enriching <i>Blautia</i> and <i>Roseburia</i> populations while reducing lipopolysaccharide (LPS)-producing bacteria to lower pathological risks. Notably, Brp may reduce the risk of T2D by increasing the concentration of lysophosphatidic acid (18:2(9Z,12Z)/0:0), indoleacrylic acid, cholic acid, and betaine, and decreasing high-risk metabolites such as 3,4-dihydroxybutyrate, xanthine, and carnitine, as well as regulating branched-chain amino acids and aromatic amino acids throughout the development of T2D.