Green tea prepared via the daily infusion method prevents non-alcoholic fatty liver disease by targeting intestinal lipid absorption, hepatic lipid metabolism and gut microbiota composition

Non-alcoholic fatty liver disease (NAFLD) is closely linked to metabolic disorders and is characterized by excess fat accumulation in the liver. Although drinking green tea has been reported to have various health benefits, the impacts and mechanisms of green tea prepared by the daily infusion method on preventing NAFLD progression remain unclear. To address this issue, we first established a human diet-mimicking mouse model induced by a high-fat, high-cholesterol, high-refined sugar Western diet (WD). Then, we supplemented green tea extract (GTE) prepared with the traditional daily infusion method at 0.5% or 1% to investigate its preventive effect on NAFLD. Results revealed that GTE consumption alleviated the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as the hepatic level of triglyceride (TG) induced by the WD. In parallel with this, GTE increased TG excretion in feces. An in vitro pancreatic lipase assay further demonstrated that GTE and catechins, especially gallate catechins, showed strong inhibitory effects on lipase activity. Furthermore, (-)-epigallocatechin-3-gallate (EGCG), a major bioactive compound of GTE, inhibited hepatic lipogenesis by increasing the level of carnitine palmitoyltransferase 1 (CPT1) in Hepa 1-6 cells. Finally, 16S rRNA sequencing of gut bacteria revealed that GTE reduced the p_Firmicutes/p_Bacteroidetes (F/B) ratio increased by the WD and modified gut microbiota composition. In summary, daily intake of GTE attenuated WD-induced NAFLD by inhibiting intestinal lipid absorption, modulating hepatic lipid metabolism and regulating gut microbiota composition. These results suggest that daily consumption of green tea prepared by the daily infusion method might contribute to preventing NAFLD.