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 iodine and selenium upon thyroid function.
Iodine is an essential element with unique role in organism : it is indispensable component of thyroid hormones . After binding with specific nuclear receptor , T3/T4 induce transcription of genetic code via mRNA and regulate proteo synthesis in most tissues . Thyroid hormones regulate rate of metabolic processes and consequently development of organism . Czech Republic was in past typical region with moderate to severe iodine deficiency . Therefore epidemiological survey was started in r and omly selected sample s of peoples . Thereafter a complex program of improving iodine supply was realized . Prompt effects of this changes were recorded , namely increase of ioduria and decrease of thyroid volume . Essential trace element selenium has a fundamental importance to the cell and body metabolism regulation by thyroid hormones . Activities of selenoenzymes deiodinases lead to the activation of prohormone T4 to active hormone T3 and the inactivation of T3 and of T4 , as well . There is unfortunately moderate to mild Se deficit in the CR . Average serum Se concentrations for the population s from 6 to 65 years are in the regions of the CR between 42 and 62 micrograms/l and urine Se values are between 8 and 15 micrograms/l . We have found statistically significant correlations among indexes of selenium status and indexes of thyroid hormone metabolism and function . Especially dangerous are concomitant deficiencies of both key elements for thyroid hormone metabolism -- I and Se -- from the point of thyroid hormone regulative functions
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 .