The Gut–Thyroid Axis: Emerging Insights into the Role of Intestinal Microbiota in Thyroid Physiology and Disease

Abstract

Background:
The human gut microbiota has emerged as a key regulator of host metabolism, immune responses, and endocrine signaling. Recent research suggests that interactions between intestinal microorganisms and thyroid physiology form a complex regulatory network referred to as the gut–thyroid axis.

Aim:
This review aims to summarize current evidence regarding the relationship between gut microbiota composition and thyroid function, with particular emphasis on mechanisms linking microbial metabolites, immune regulation, and micronutrient metabolism with thyroid hormone homeostasis.

Methods:
A narrative review of recent literature was conducted, focusing on studies investigating associations between gut microbiota and thyroid disorders, including autoimmune thyroid diseases, hypothyroidism, Graves’ disease, and thyroid cancer.

Results:
Accumulating evidence indicates that intestinal microbiota may influence thyroid function through several mechanisms, including modulation of micronutrient absorption (iodine, selenium, and iron), regulation of immune responses, and production of microbial metabolites such as short-chain fatty acids. Dysbiosis has been consistently associated with autoimmune thyroid diseases and may contribute to the pathogenesis of thyroid cancer and other thyroid dysfunctions. Emerging studies also suggest that probiotic supplementation and dietary interventions targeting the microbiome may improve thyroid-related outcomes.

Conclusion:
The gut–thyroid axis represents a promising area of research in endocrine physiology. Understanding the complex interactions between intestinal microbiota and thyroid function may provide new insights into the pathogenesis of thyroid diseases and open novel therapeutic opportunities.