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 .
Double-Fortified Salt Is Efficacious in Improving Indicators of Iron Deficiency in Female Indian Tea Pickers123
Poor iron status affects 50 % of Indian women and compromises work productivity , cognitive performance , and reproduction . Among the many strategies to reduce iron deficiency is the commercial fortification of iodized table salt with iron to produce a double-fortified salt ( DFS ) . The objective of this study was to test the efficacy of DFS in reducing iron deficiency in rural women of reproductive age from northern West Bengal , India . The participants were 212 women between 18 and 55 y of age who worked as full-time tea pickers on a large tea estate . Participants in the r and omized , controlled , double-blind study were assigned to use either DFS or a control iodized salt for 7.5 to 9 mo . The DFS was fortified with 3.3-mg ferrous fumarate ( 1.1-mg elemental iron ) per kg of iodized salt , whereas the control salt contained only iodine ( 47 mg/kg potassium io date ) , and both salt varieties were distributed gratis to the families of participants at 0.5 kg/mo for each 2 household members . At baseline , 53 % of participants were anemic ( hemoglobin < 120 g/L ) , 25 % were iron deficient ( serum ferritin < 12 μg/L ) , and 23 % were iron-deficient anemic . Also , 22 % had a transferrin receptor concentration > 8.6 mg/L and 22 % had negative ( < 0.0 mg/kg ) body iron stores . After 9 mo the participants receiving DFS showed significant improvements compared with controls in hemoglobin ( + 2.4 g/L ) , ferritin ( + 0.13 log10 μg/L ) , soluble transferrin receptor ( −0.59 mg/L ) , and body iron ( + 1.43 mg/kg ) , with change in status analyzed by general linear models controlling for baseline values . This study demonstrated that DFS is an efficacious approach to improving iron status and should be further evaluated for effectiveness in the general population . This trial was registered at clinical trials.gov as NCT01032005
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 .