Although observational evidence suggests that concentrations of selenium , zinc , and iron are positively associated with iodine status , data from r and omized controlled trials fail to confirm this relationship .
Context The metabolism of thyroid hormones , which are essential for normal development , involves many proteins and enzymes .
It requires iodine as a key component but is also influenced by several other micronutrients , including selenium , zinc , iron , and vitamin A. Objective This systematic review was design ed to investigate the effect of micronutrient status and supplementation on  iodine status and thyroid hormone concentrations .
Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency
Purpose Selenium is an essential trace mineral and a component of selenoproteins that are involved in the production of thyroid hormones and in regulating the immune response . We aim ed to explore the effect of low-dose selenium supplementation on thyroid peroxidase antibody ( TPO-Ab ) concentration and thyroid function in pregnant women from a mild-to-moderate iodine-deficient population . Methods Sample s and data were from a secondary analysis of Selenium in PRegnancy INTervention ( SPRINT ) , a double-blind , r and omized , placebo-controlled study that recruited 230 women with singleton pregnancies from a UK antenatal clinic at 12 weeks of gestation . Women were r and omized to receive 60 µg/day selenium or placebo until delivery . Serum thyroid peroxidase antibodies ( TPO-Ab ) , thyrotropin ( TSH ) and free thyroxine ( FT4 ) were measured at 12 , 20 and 35 weeks and thyroglobulin antibodies ( Tg-Ab ) at 12 weeks . Results 93.5 % of participants completed the study  . Se supplementation had no more effect than placebo in decreasing TPO-Ab concentration or the prevalence of TPO-Ab positivity during the course of pregnancy . In women who were either TPO-Ab or Tg-Ab negative at baseline ( Thy-Ab−ve ) , TSH increased and FT4 decreased significantly throughout gestation ( P < 0.001 ) , with no difference between treatment groups . In women who were Thy-Ab+ve at baseline , TSH tended to decrease and was lower than placebo at 35 weeks ( P = 0.050 ) . FT4 fell more on Se than placebo supplementation and was significantly lower at 35 weeks ( P = 0.029 ) . Conclusions Low-dose selenium supplementation in pregnant women with mild-to-moderate deficiency had no effect on TPO-Ab concentration , but tended to change thyroid function in Thy-Ab+ve women
Although observational evidence suggests that concentrations of selenium , zinc , and iron are positively associated with iodine status , data from r and omized controlled trials fail to confirm this relationship .
Context The metabolism of thyroid hormones , which are essential for normal development , involves many proteins and enzymes .
It requires iodine as a key component but is also influenced by several other micronutrients , including selenium , zinc , iron , and vitamin A. Objective This systematic review was design ed to investigate the effect of micronutrient status and supplementation on  iodine status and thyroid hormone concentrations .