IGHE and food allergy: In particular, IgE and specific IgE to food allergen play a critical role in the pathogenesis of AD and food allergy.37–39 A reduced abundance of B. fragilis in the AD group, which prevents inflammation through its polysaccharide A by restoring Th1/Th2 balance,40 was also found in previous studies.16,27 These results suggest that the redox-dysregulated gut environment of children with AD during early development could cause gut microbiome perturbation and SCFA dysbiosis in later life by limiting the colonization of B. fragilis.