Exploring association of tea consumption with food allergy: findings and validation based on a prospective cohort study

Food allergies (FA) are characterized by Th2-dominant immune reactions and intestinal barrier dysfunction with increased incidence worldwide. Tea intake can significantly affect biological activities and health-related allergic diseases. However, the correlation between tea intake and the risk of FA or the underlying mechanism have not been well explained. This study aimed to unveil the correlation between tea intake and the risk of FA, as well as the underlying mechanisms involving gut microbiota and allergenic factors. A prospective cohort study was conducted on the connection between tea intake and the risk of FA based on the UK Biobank. A two-sample Mendelian randomization (MR) study was conducted to further analyse the causal genetic association. A murine model (BALB/c WT mice) of ovalbumin (OVA)-induced FA was utilized for experimental validation. The tea polyphenol epigallocatechin gallate (EGCG) was assessed for its effects on allergic symptoms, serum levels, Th1/Th2 cytokine balance, and gut microbiota, to elucidate the underlying mechanisms. The population study including 411,584 UK Biobank participants revealed a lowered risk of FA upon tea intake. Further analysis of MR showed no genetic association with FA incidence. The experimental analysis verified that the tea polyphenol EGCG significantly alleviated allergic symptoms, reduced OVA-specific IgE and histamine levels, and shifted the Th1/Th2 balance toward Th1 dominance. EGCG improved intestinal barrier integrity by upregulating tight junction proteins and restored the Firmicutes/Bacteroidetes ratio in the gut microbiota. Mechanistically, EGCG downregulated the TLR4/MyD88/NF-κB signalling pathway, reducing inflammation associated with allergic sensitization. A significant correlation between tea intake and FA was identified, with emphasis on EGCG-mediated intervention by mitigating symptoms, restoring immune balance, and enhancing gut health. This study provides evidence supporting the reduced risk of FA upon tea intake and unveils the mechanisms underlying tea polyphenolic EGCG-mediated underpinnings.