Noni (Morinda citrifolia L.) fruit polysaccharide ameliorated high-fat diet-induced obesity by modulating gut microbiota and improving bile acid metabolism

To investigate the anti-obesity effect of a noni (Morinda citrifolia L.) fruit polysaccharide (NFP) and its potential mechanisms, 24 male C57BL/6J mice were randomly divided into three groups—normal control group, high-fat diet (HFD) group, and NFP-administration group and were gavaged once a day for 12 weeks. The body weights, serum lipid parameters, bile acid (BA)-related proteins, fecal BA, and cecal bacteria of the mice were obtained and analyzed. Results indicate that NFP supplementation (200 mg/kg·bw) reduced the body weight, energy intake, and serum and liver lipids of the HFD mice. Further studies found that NFP activated the hepatic and colonic farnesoid X receptor and increased the excretion of fecal-conjugated BAs, particularly tauro-alpha-muricholic acid and tauro-beta-muricholic acid. In addition, NFP modulated the intestinal microbiota and increased the relative abundance of Lactobacillus in the HFD mice. In conclusion, NFP modulated gut microbiota and improved BA metabolism, which may be the main mechanism behind NFP alleviation of fat accumulation and dyslipidemia in mice under HFD.