Across 4 studies, 2 reported beneficial effects of selenium supplementation on reducing thyroglobulin antibody (TgAb) levels, while 2 reported neutral effects; effect sizes were predominantly small to moderate. The evidence is mixed, with one meta-analysis showing a moderate beneficial effect at 3 months but not at 6 months, and another large meta-analysis finding no significant change. Most studies focused on patients with Hashimoto thyroiditis (clinical population), and the median study duration was 182 days (6 months) in the single study reporting duration, though effects were observed at 3 months in one analysis.
Caveats: Evidence base is small (only 4 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. The beneficial effect observed in one meta-analysis was only significant at 3 months, not at 6 months, suggesting possible transient effects. One study included patients with Graves-Basedow disease, not exclusively Hashimoto thyroiditis, which may limit generalizability.
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
During a 6-month treatment, the use of (...) the combination of selenium, and Myo-inositol did not effectively reduce (...) TgAb (Se+Myo-inositol: SMD: -3.64, 95% CI: -9.20,1.92)