Across 3 studies (2 meta-analyses and 1 systematic review), 2 reported beneficial effects on reducing thyroglobulin antibody levels, with effect sizes ranging from small to moderate. The evidence primarily comes from patients with Hashimoto thyroiditis. No consistent dose or form data were reported.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. The two meta-analyses on Hashimoto thyroiditis produced conflicting results: one found a moderate beneficial effect at 3 months but not sustained at 6 months, while the other found no significant effect overall. The third study on Graves-Basedow disease is limited by very small sample size.
Adverse effects were comparable between the intervention and control groups (OR 0.89 [CI 0.46 to 1.75]; 16 cohorts; 1339 participants; I²=0%).
from: Selenium Supplementation in Patients with Hashimoto Thyroiditis: A Systematic Review and MThe serum TgAb levels decreased at 3 months (SMD = -0.46, 95%CI: -0.79 to -0.12, P = .007) but not at 6 months.
No significant changes were observed in TGAb
selenium supplementation was associated with significant improvements in TSH, FT4, FT3, TPOAb, TgAb, and TRAb levels