Citrus Pectin Supplementation Alleviated Hepatic Lipid Accumulation through Gut Microbiota Indole Lactic Acid Promoting Hepatic Bile Acid Synthesis and Excretion

Metabolic-associated fatty liver disease (MAFLD) represents a critical global health challenge. A few studies have suggested that citrus pectin may confer protective effects against MAFLD; however, the underlying mechanism remains unclear. The gut microbiota and its metabolites strongly contribute to MAFLD regulation by the gut‒liver axis. The present study explored the influence of pectin intervention on liver lipid accumulation in high-fat and high-sugar diet-fed mouse models. Pectin supplementation alleviated hepatic lipid accumulation and substantially restructured the gut microbial communities, particularly enhancing the proliferation of Akkermansia muciniphila (A. muciniphila) and Escherichia coli (E. coli), which subsequently increased indole-3-lactic acid (ILA) production. Mechanistic investigations revealed that ILA upregulated hepatic CYP7A1 and FXR-BSEP expression, stimulating hepatic bile acid biosynthesis and biliary excretion to alleviate liver steatosis. Results of previous fecal microbiota transplantation (FMT) and antibiotic-mediated microbial dysbiosis studies have confirmed the microbiota-dependent nature of the therapeutic effects of pectin. Furthermore, the administration of exogenous ILA has been demonstrated to be an effective intervention for the rescue of metabolic dysregulation in dysbacteriosis mouse models. This work delineated an unrecognized dietary pectin-microbiota-ILA-hepatic bile acid synthesis and excretion regulatory axis for the improvement of MAFLD.