Abstract

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global health burden with limited therapeutic options. Cinnamomum cassia, a medicinal-food homologous plant, contains principal bioactive cinnamaldehyde (CA), whose anti-MASLD mechanisms require clarification. This study employed both a high-fat diet (HFD)-induced MASLD model and a free fatty acid (FFA)-stimulated cell model. CA administration attenuated intracellular lipid accumulation in vitro and ameliorated both hepatic steatosis and systemic hyperlipidemia in vivo, while inhibiting hepatic lipid peroxidation. Mechanistically, integrated RNA-seq, network pharmacology, siRNA, immunofluorescence, and transmission electron microscopy analyses identified the SIRT1/FOXO1–autophagy axis as CA’s key regulatory pathway. Gut microbiome profiling revealed CA’s capacity to ameliorate HFD-induced dysbiosis, particularly enriching Lachnospiraceae_NK4A136. Fecal microbiota transplantation (FMT) and Spearman correlations link serum lipids and hepatic injury factors to gut microbiota, indicating partially microbiota-mediated metabolic modulation by CA. Collectively, CA ameliorates MASLD through coordinated autophagy enhancement and microbial homeostasis restoration, holding promise as a functional food ingredient for metabolic liver disease prevention.