Protective effects of catechin (C) and epigallocatechin gallate (EGCG) against high-fat diet (HFD)-exacerbated Salmonella infection in mice

Catechins prevent HFD-induced exacerbation of Salmonella infection. • Salmonella infection is promoted by HFD in mice. • HFD causes intestinal dysbacteriosis in Salmonella -infected mice. • Catechins exerts protective effects on HFD-fed and Salmonella -infected mice. • C and EGCG modulate the gut microbiota into distinct profiles. Salmonella is one of the most prevalent foodborne pathogens. This study investigated the impact of HFD on Salmonella infection and the preventive effects of tea-derived polyphenols. Results showed that HFD decreased the survival rate of Salmonella -infected mice, while catechin (C) and epigallocatechin gallate (EGCG) supplementation increased survival rates, with EGCG being more effective. HFD promoted pro-inflammatory cytokines and inhibited intestinal epithelial barrier proteins, but catechins, especially EGCG, restored these levels. 16S rDNA sequencing revealed HFD-induced gut microbiota disruptions. Both catechins altered bacterial composition and diversity, with distinct profiles for C and EGCG. The relative abundance of Desulfovibrio and the Eubacterium coprostanoligenes group was modulated by both catechins, and nine bacteria were identified as biomarkers for EGCG treatment. In summary, Salmonella infection is exacerbated by HFD, but catechins, particularly EGCG, offer protective effects, providing valuable insights for controlling pathogenic infections by tea polyphenols or related functional foods.