Selenium for thyroid health
German researchers have found that supplementing with selenium may slow the progression of autoimmune thyroid disease (AITD), and may be most effective at the onset of thyroiditis. AITD refers to a number of different disorders in which the immune system attacks the cells of the thyroid gland, causing symptoms of thyroid disease. AITDs include both disorders of hypothyroidism—reduced thyroid hormone production—and hyperthyroidism—excess thyroid hormone production.
Researchers believe that a deficiency in selenium may contribute to the development of AITD because selenium has a direct impact on immune system enzymes. Dr. Barbara Gasnier, MD, of the Medizinische Klinik University, Munich, Germany, led a study that consisted of 72 women with a mean age of 47. All had AITD, and all had thyroid peroxidase (TPO) antibodies greater than 350 units per milliliter of blood. TPO antibodies are not present in healthy individuals. Half the participants received 200 mcg of selenium per day for three months, while the other half received a placebo. All patients were normalized on their thyroid hormone treatment.
TPO antibody levels were measured at the conclusion of the three-month study period. Nine of the patients taking selenium had TPO antibody levels return to normal. By contrast, only two members of the placebo control group had TPO antibody levels return to normal. In the selenium group, the TPO antibody levels had a mean decrease of 40%, compared to a 10% increase in the placebo group. The higher the TPO antibody levels at the onset of the test, the greater the reduction at the end of the three-month study period. The researchers concluded that selenium supplementation may reduce thyroid inflammation in patients with AITD.
Reference: The Journal of Clinical Endocrinology & Metabolism; Vol. 87, No. 4, 1687-91.
Another study:
Duntas et al., Athens, Greece, assessed the effects of selenium (Se) in the form of selenomethionine (SeMe) as a single or adjunctive treatment with L-T4 in patients with autoimmune thyroiditis (AIT). Three groups of patients were studied. Gr I (n = 31) treated with SeMe 200 µg/day plus L-T4 to normalize TSH between 0.3 and 2.0 µU/ml, Gr II (n = 17) SeMe plus placebo and Gr III (n = 29) L-T4 plus placebo. The study period was 6 months and the patients were assessed at baseline and after 3 and 6 months of treatment. In Gr I 16/31 patients showed a decrease of anti-TPO by 37 % at 3 months and 86 % at 6 months. In 11/31 the decrease was only 28 % and 4/31 did not show any decrease of TPO. In Gr II in 13/17 patients TPO decrease was 77 and 81 % respectively, while in 4/17 no change was observed. In Gr III 23/29 showed a decrease of 28 % and 44 % respectively, and in 6/29 these values were 13 and 22 % respectively. It was additionally shown that SeMe is slowly and effectively absorbed. The authors conclude that selenium may be effective as a sole treatment of autoimmune thyroid disease. Comment: Selenium became of interest in thyroidology in the last decade for several reasons. First it was shown that it is a necessary element in the function of thyroid hormone deiodinases that play an essential role in thyroid hormone metabolism and production of the metabolic active iodothyronine T3 from the prohormone T4. Furthermore, it has been shown that addition of selenium to children living in areas of severe iodine deficiency may prevent permanent damage to the thyroid. This report is interesting in that selenium may also have a role in suppression of thyroid autoimmunity. Further studies are necessary to confirm these findings and to elucidate the mechanism of immune suppression. One possibility could be that administration of selenium activates enzymes, such as glutathion peroxidase and thioredoxin reductase, that have anti-oxidant activity by inactivating free radicals. Free radicals have been implicated in stimulation of autoimmunity.
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Selenium for Thyroid Health (research article) 
