Beyond celiac disease: the potential role of gluten in Hashimoto's thyroiditis.

Celiac disease (CD) and Hashimoto's thyroiditis (HT) frequently coexist, suggesting that shared mechanisms of autoimmunity extend beyond the intestine. In CD, the pathogenic role of gluten is firmly established; in HT, however, gluten is better viewed as a candidate modifier rather than a proven universal trigger. This review synthesizes current evidence on how gluten may influence the CD-HT axis through gut dysbiosis, epithelial barrier dysfunction, immune cross-reactivity, and epigenetic regulation. We also examine the clinical evidence for gluten-free diet (GFD) use in three settings: classical CD, CD-HT comorbidity, and HT without confirmed CD. Current data support lifelong GFD in CD and suggest that patients with both CD and HT may gain indirect thyroid-related benefit as intestinal inflammation improves. By contrast, evidence remains insufficient to recommend routine gluten withdrawal for all patients with non-celiac HT. Long-term GFD also carries practical and nutritional burdens that require professional supervision. Overall, the most defensible clinical approach is targeted screening for CD or other gluten-related disorders in selected HT patients, followed by individualized dietary counseling rather than universal restriction. Future work should prioritize mechanistically informed, adequately powered randomized trials to identify which thyroid-autoimmune phenotypes, if any, are most likely to benefit from gluten exclusion.