Greek researchers studied the impact of selenium treatment on antithyroid peroxidase (TPO) levels in patients with Hashimoto's thyroiditis. In the study, patients received 200 mcg of selenium (an l-selenomethionine supplement) orally for 6 months. Half the group continued taking selenium for an additional six months, and the other half stopped selenium supplementation. The researchers found that the anti-TPO levels were reduced substantially during the first six months, with an approximately 5.6% reduction after 3 months, 9.9% after six months, and an additional 8% in the additional six months for the groups that continued with supplementation. The group that stopped supplementation saw a 4.8% increase in the antibody levels during the second six months. MORE INFO: More on selenium and thyroid antibodies
Source: Mazokopakis EE, et. al. "Effects of 12 Months Treatment with l-Selenomethionine on Serum Anti-TPO Levels in Patients with Hashimoto's Thyroiditis." Thyroid. 2007 Aug;17(7):609-12.
Finally, some published research bringing to the surface the what we have known about the therapeutic effects of selenomethionine on HT. In many studies, lowering autoantibody levels was shown greater when combinations on antioxidatns were given as thyroid co-factos such as retinol, tocopherol, molecular iodine/iodide, and calciferol.