Previous studies have suggested that some Lactobacillus and Bifidobacterium species have significant structural homology with thyroid peroxidase and anti-thyroglobulin and can competitively bind thyroid peroxidase antibodies and anti-thyroglobulin antibodies to induce autoimmune thyroid disease through molecular mimicry (Kiseleva et al., 2011; Benvenga and Guarneri, 2016). This evidence concerns the gene TPO and autoimmune thyroid disease.