Depolymerized Fucoidan Alleviates High-Fat Diet-Induced Obesity in Association with Alterations in Gut Microbiota and Metabolic Profiles

Obesity is a major global health concern associated with various metabolic disorders. Fucoidan, a seaweed-derived sulfated polysaccharide, has shown potential in alleviating obesity through modulation of gut microbiota. However, comparative effects of native and depolymerized fucoidan (Dfuc) on HFD-induced obesity and gut microbiota dysbiosis remain unclear. In this study, we compared the anti-obesity effects of fucoidan and Dfuc and evaluated their regulatory effects on gut microbiota and microbial metabolites in HFD-fed mice. Results showed that fucoidan and Dfuc reduced body weight gain, fat accumulation and hepatic lipid abnormalities. They also alleviated liver injury and oxidative stress and inflammation in hepatic and colonic tissues, with Dfuc significantly improving parameters such as serum AST, hepatic MDA, SOD activity, and TNF-α expression compared to the HF group. Furthermore, gut microbiota analysis showed that both fucoidan and Dfuc treatments enriched Alloprevotella and Allobaculum, while fucoidan increased Akkermansia and Blautia, and Dfuc promoted Bifidobacterium and Romboutsia. Moreover, metabolite analysis showed that Dfuc significantly increased fecal acetate and propionate concentrations, and induced more pronounced changes in fecal metabolites related to amino acid, carbohydrate, and bile acid metabolism. These findings suggest that Dfuc holds potential as a functional food ingredient for alleviating HFD-induced obesity and gut microbiota dysbiosis.