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 .
Urinary selenium and iodine during pregnancy and lactation.
The New Zeal and environment is low in selenium and iodine , and is therefore ideally suited for the study of these anionic trace elements . The aim of this study was to determine urinary excretion of selenium and iodine during pregnancy and postpartum as part of an investigation of the influence of pregnancy and lactation on selenium metabolism in women of low selenium status . In a double-blind placebo-controlled study , 35 women in the earliest stages of pregnancy and 17 non-pregnant women were recruited in Dunedin , New Zeal and . Eighteen pregnant women received 50 microg selenium as L-selenomethionine , while the others received a placebo daily during pregnancy and 12 months postpartum . The non-pregnant women received the supplement , serving as a positive control . Blood sample s and twenty-four hour urine sample s were collected monthly during pregnancy and at 3 , 6 , and 12 months postpartum for analysis of selenium and iodine . Selenium content in plasma and urinary excretion of selenium fell during pregnancy ; however , total excretion of selenium was greater during pregnancy than postpartum . Urinary iodine excretion was much lower than reported previously in New Zeal and . Due to large intra- and inter-subject variability , no trends in iodide excretion were observed . Factors which influence urinary excretion of selenium include dietary intake , but more closely , plasma concentrations of selenium ( which is probably related to total selenium pool ) , creatinine excretion and therefore lean body mass , and glomerular filtration rate . The exact mechanism and sequence of events remains unclear and future studies incorporating new speciation techniques are necessary
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 .