A future perspective on upper respiratory tract diseases: diet and gut microbiota

Abstract Upper respiratory tract diseases (URTDs), such as allergic rhinitis, asthma, and influenza, impose a significant burden on global health due to their high prevalence and immune heterogeneity that complicates prevention and treatment. Gut microbiota modulation induced by dietary intervention has emerged as a promising strategy to regulate respiratory immune homeostasis. This review provides a comprehensive and up-to-date summary of tripartite relationship between diet, gut microbiota, and URTDs. The paper discussed the impact of gut microbiota composition and its metabolites on URTD pathogenesis, through epithelial barrier integrity modulation and immune pathways, such as the Treg/Th17 balance and type-I interferon. Additionally, the impact of dietary patterns and specific nutrients on gut microbiota composition were summarised, and available preclinical and clinical evidence supporting dietary strategies for URTD management was discussed. Finally, future research directions are outlined in this review, such as the application of multi-omics to identify predictive biomarkers, the development of personalised nutrition strategies based on microbial function, the exploration of postbiotics and engineered bacterial therapies, and the need for mechanistically informed, high-quality clinical trials. By elucidating the complex interactions in diet–microbiota–immune axis, this review offers mechanistic insights and nutritional strategies for URTDs prevention and intervention.