Disorders of the thyroid gland are common, more prevalent in women than in men, and range from inflammatory to neoplastic lesions. Autoimmune thyroid diseases (AITD) affect 2–5% of the population, while thyroid cancer is the most frequent endocrine malignancy. Treatment for AITD is still restricted to management rather than prevention or cure. Progress has been made in identifying genetic variants that predispose to AITD and thyroid cancer, but the increasing prevalence of all thyroid disorders indicates that factors other than genes are involved. The gut microbiota, which begins to develop before birth, is highly sensitive to diet and the environment, providing a potential mechanism for non-communicable diseases to become communicable. Its functions extend beyond maintenance of gut integrity: the gut microbiota regulates the immune system, contributes to thyroid hormone metabolism and can generate or catabolize carcinogens, all of which are relevant to AITD and thyroid cancer. Observational and interventional studies in animal models support a role for the gut microbiota in AITD, which has been confirmed in some reports from human cohorts, although considerable geographic variation is apparent. Reports of a role for the microbiota in thyroid cancer are more limited, but evidence supports a relationship between gut dysbiosis and thyroid cancer.

甲状腺疾病很常见，女性比男性更常见，范围从炎症到肿瘤性病变。自身免疫性甲状腺疾病 (AITD) 影响 2-5% 的人口，而甲状腺癌是最常见的内分泌恶性肿瘤。 AITD 的治疗仍然仅限于管理而不是预防或治疗。在识别易患 AITD 和甲状腺癌的基因变异方面已经取得了进展，但所有甲状腺疾病患病率的不断增加表明，除了基因之外还有其他因素参与其中。肠道微生物群在出生前就开始发育，对饮食和环境高度敏感，为非传染性疾病变成传染性疾病提供了潜在机制。其功能超出了维持肠道完整性的范围：肠道微生物群调节免疫系统，促进甲状腺激素代谢，并能产生或分解代谢致癌物，所有这些都与 AITD 和甲状腺癌相关。动物模型的观察和介入研究支持肠道微生物群在 AITD 中的作用，这一点在人类队列的一些报告中得到了证实，尽管明显存在相当大的地理差异。关于微生物群在甲状腺癌中的作用的报道较为有限，但有证据支持肠道菌群失调与甲状腺癌之间的关系。