Starch-EGCG complex enhances EGCG bioavailability through microbial metabolism and ameliorates metabolic-associated fatty liver disease via gut-liver axis.

Starch-polyphenol complexes are recoganized as a new type of resistant starch, while their promotion of polyphenol bioavailability in vivo and potential amelioration impact on metabolic-associated fatty liver disease (MAFLD) remains unclear. In this study, maize starch-epigallocatechin gallate (MaS-EGCG) complexes with an A + V crystalline polymorph were synthesized. In vivo imaging showed that the MaS-EGCG complex exhibited prolonged gastrointestinal retention, with a significantly enriched amount reaching the colon. Notably, the hepatic EGCG content was enhanced by 61.8 % after 8-h ingestion of MaS-EGCG complex compared to ingested EGCG alone (p < 0.05). In a high-fat diet-induced MAFLD model, the MaS-EGCG complex exhibited strong anti-inflammatory and antioxidant activities, reducing lipid accumulation via activated AMPK pathway. It further enriched beneficial gut microbiota (Akkermansia, Bacteroides, Parabacteroides) and short-chain fatty acids, and enhanced intestinal barrier integrity through upregulating occludin and ZO-1 expression. Metabolomics identified that the MaS-EGCG complex had higher levels of EGCG and its microbial metabolites (glucuronidated, methylated, sulphated forms) in the colon compared to ingested EGCG alone. Collectively, these findings confirm the MaS-EGCG complex enhances EGCG bioavailability via microbiota-polyphenol synergistic interaction and its amelioration impact on MAFLD via the gut-liver axis, highlighting the potential of starch-polyphenol complexes as functional foods to enhance human health.