The Role of the Microbiome in Hashimoto’s Disease - Pathogenesis and Therapeutic Implications: Narrative Review

Objective: The aim of this narrative review was to summarize the current state of knowledge regarding the role of the gut microbiome in the pathogenesis of Hashimoto’s disease and to discuss potential microbiome-targeted therapeutic strategies. Methods: A narrative literature review was conducted using publications indexed in the PubMed, Google Scholar and Scopus databases. Original research articles, systematic reviews, and meta-analyses focusing on Hashimoto’s disease and gut microbiota interactions were included. Most studies were selected from the past 10-15 years, with approximately 80% of the included literature published within the last five years (2021–2025), ensuring up-to-date evidence. Key findings: Available evidence indicates that patients with Hashimoto’s disease exhibit gut dysbiosis characterized by reduced microbial diversity, decreased abundance of short-chain fatty acid-producing bacteria, and an overrepresentation of potentially pathogenic microorganisms. These alterations are associated with impaired intestinal barrier integrity, increased systemic inflammation, and dysregulation of immune responses, particularly an imbalance between regulatory T cells and Th17 lymphocytes. Furthermore, microbiome disturbances may contribute to thyroid autoimmunity through mechanisms such as molecular mimicry and translocation of bacterial antigens. Emerging studies suggest that dietary modification, probiotic and synbiotic supplementation, and fecal microbiota transplantation may positively influence thyroid function and immune regulation. Conclusions: Although levothyroxine replacement remains the standard treatment for Hashimoto’s disease, modulation of the gut microbiome represents a promising adjunctive therapeutic approach. Further well-designed clinical trials are required to clarify causal relationships and evaluate the efficacy of microbiome-targeted interventions in autoimmune thyroid disease.