High-Fat Diet, Gut Microbiota, and Atopic Dermatitis: Mechanistic Insights

Atopic dermatitis (AD) is a chronic inflammatory skin disease whose global prevalence continues to rise, particularly in populations adopting Westernized lifestyles. Accumulating evidence suggests that dietary factors, especially high-fat diet (HFD), act as important environmental modifiers of AD susceptibility and disease severity. Beyond its metabolic consequences, HFD profoundly reshapes gut microbiota composition and function, leading to altered microbial metabolites, impaired intestinal barrier integrity, and low-grade systemic inflammation. Emerging studies support the concept of a gut–skin axis, through which HFD-induced gut dysbiosis contributes to immune dysregulation and skin inflammation. Experimental models demonstrate that HFD reduces microbial diversity, suppresses the production of immunoregulatory metabolites such as short-chain fatty acids, and promotes translocation of microbial products, collectively amplifying Th2- and Th17-skewed immune responses characteristic of AD. Consistently, patients with AD exhibit distinct gut microbial signatures associated with barrier dysfunction and heightened inflammatory activity. This review synthesizes current evidence linking HFD, gut microbiota dysbiosis, and AD pathogenesis, with a particular focus on microbial metabolites, intestinal barrier integrity, and immune pathways along the gut–skin axis. We further discuss translational implications, highlighting dietary modulation and microbiota-targeted strategies as potential adjunctive approaches for AD management.