Is selenium useful for Hashimoto's thyroiditis?

Selenium is often recommended for the management of symptoms associated with Hashimoto's thyroiditis. It has long been recognised that selenium, together with iodine and iron are essential for normal thyroid function. There have been numerous studies reporting that selenium administration improves well being overall in patients with Hashimoto's thyroiditis. This is particularly important in relation to the non-specific symptoms of the Hashimoto's Associated Syndrome such as tiredness, lethargy and fibromyalgia that occur in the presence of normal thyroid function and are thought to be an expression of autoimmune pathophysiology. Most of these studies also demonstrate a reduction in thyroperoxidase (TPO) antibody titres, suggesting  the mechanism may relate to reduced autoimmune reactivity with an adequate selenium supply saturating  expression of circulating selenoprotein P.  However most of the studies reported have too low numbers of cases to provide significant outcome. A Cochrane collaboration  study (link to abstract) incorporating four studies and 463 patients  meeting inclusion criteria concluded that there was not sufficient evidence to recommend selenium  supplementation as routine treatment for Hashimoto's thyroiditis. Nonetheless there was no adverse reaction to selenium in the doses provided (up to 200 mcg daily). Higher doses run the risk of causing selenosis. That level of supplementation can also be obtained with a daily serving of nuts, particularly Brazil nuts. Given that some patients do obtain significant relief, in the absence of any adverse reaction it is indeed a therapeutic option worth discussion.