Autoimmune thyroiditis is a common disease with high prevalence rates (4-13% in the US) that increase with advancing age. A meta-analysis of 20 studies showed that pts with AIT have an elevated risk of depression and anxiety disorders (17% and 36% respectively) compared with health controls. Besides typical levothyroxine treatment, selenium supplementation (generally 200mcg daily) can reduce thyroid antibodies and improve mood/well being. The thyroid gland is characterized by a high concentration of selenium, which is incorporated into selenoproteins. Some of these selenoproteins have an important antioxidant activity, removing oxygen free radicals generated during the production of thyroid hormones. Being incorporated into iodothyronine deiodinases, selenium also plays an essential role in the metabolism of thyroid hormones.

Publication reference : Siegmann E et al. Association of depression and anxiety disorders with autoimmune thyroiditis: a systematic review and meta-analysis. JAMA Psychiatry 2018; 75: 577-584
Reference URL: https://pubmed.ncbi.nlm.nih.gov/29800939/
Publication reference : Toulis KA et al. Selenium supplementation in the treatment of Hashimoto's thyroiditis: a systematic review and a meta-analysis. Thyroid 2010; 20: 1163-1173
Reference URL: https://pubmed.ncbi.nlm.nih.gov/20883174/