Winther KH, et al. - In this overview, authors serve an appraisal of current data for or against selenium supplementation in patients with autoimmune thyroid diseases, and discusses possible effect mechanisms. The evidence showed that the use of selenium supplementation as adjuvant therapy to standard thyroid medication may be widespread, but a growing body of evidence yields equivocal results. The available data from trials does not support routine selenium supplementation in the standard treatment of patients with autoimmune thyroiditis or Graves' disease. Nevertheless, association of moderate to severe selenium deficiency may offer benefits in preventing, as well as treating, these disorders. In addition, molecular mechanisms have been proposed, but further studies are required.