Effects of three doses of tea polyphenols on lipid metabolism, intestinal barrier function, and gut microbiota in overweight mice

BACKGROUND Overweight induced by a high‐fat diet (HFD) is closely associated with dyslipidemia, oxidative stress, intestinal barrier dysfunction, and gut microbiota imbalance. Tea polyphenols have shown metabolic benefits; however, comparative information regarding their biological effects across different intervention doses remains limited. This study evaluated the effects of different doses of green tea polyphenols (GTP) on metabolic disorders in HFD‐induced overweight mice. RESULTS Green tea polyphenols reduced body weight gain and improved lipid metabolism without affecting food intake, with the strongest overall effects observed in the 300 mg kg −1 group. Compared with the normal control (NC) group, the HFD group showed increased serum total cholesterol (TC) (+104.01%), triglyceride (TG) (+57.06%), and low‐density lipoprotein cholesterol (LDL‐C) (+64.44%) levels and decreased high‐density lipoprotein cholesterol (HDL‐C) (−41.29%). These lipid disturbances were attenuated significantly by GTP intervention, especially in the 300 mg kg −1 group ( P < 0.05). GTP also alleviated liver injury and oxidative stress, as indicated by decreased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, increased catalase (CAT) and superoxide dismutase (SOD) activities, increased glutathione (GSH) levels, and reduced malondialdehyde (MDA) levels. In addition, GTP intervention was associated with increased colonic goblet cell numbers and changes in the expression of the tight‐junction proteins claudin‐1 and occludin. Gut microbiota analysis revealed a reduced Firmicutes/Bacteroidota ratio and enrichment of beneficial bacteria, with the high‐dose group showing a microbial profile closer to that of the normal controls. CONCLUSION Green tea polyphenol ameliorated HFD‐induced metabolic abnormalities involving lipid metabolism, oxidative stress, and intestinal barrier function, and these improvements were accompanied by marked alterations in gut microbial composition. Among the tested doses, 300 mg kg −1 showed the strongest overall effects.