IGHE and allergic disease: Various studies have shown that the numbers of Lactobacillus were significantly reduced in an AR group and that supplements containing Lactobacilli or their metabolite lactic acid could alleviate the disease by improving the intestinal epithelial barrier, decreasing the levels of allergen-specific IgE, and increasing the levels of regulatory cytokine TGF-β [142–146] to alleviate allergic diseases.