Research synthesisHigh evidenceModerate effect5 studies · 4 beneficial · 1 neutral · 0 harmful
Across 5 studies on selenium for reducing thyroid peroxidase antibody (TPOAb) levels, 4 reported beneficial effects and 1 was neutral. The two highest-quality meta-analyses both found moderate-to-large statistically significant reductions in TPOAb among patients with Hashimoto thyroiditis (e.g., SMD -0.80 at 6 months in one 2025 meta-analysis of 1,610 patients). Effects were typically observed at 3–6 months (median study duration 182 days), supporting sustained supplementation for antibody reduction.
- Studied populations: patients with Hashimoto thyroiditis (HT); one study also included patients with Graves-Basedow disease
Caveats: Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). The neutral study tested selenium combined with myo-inositol, so the lack of effect in that arm may reflect the combination or the supplement as a whole. One smaller review had a very small sample (15 participants) and lower evidence quality. Dose data were not reported across studies, limiting dose-specific recommendations.
Generated Jun 17, 2026