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 .
High vitamin D status in younger individuals is associated with low circulating thyrotropin.
BACKGROUND Vitamin D is an immunomodulator and may affect autoimmune thyroid diseases . Vitamin D has also been shown to influence thyrocytes directly by attenuating thyrotropin (TSH)-stimulated iodide uptake and cell growth . However , it is unclear how vitamin D status is related to TSH at the population level . The goal of the present study was to investigate the relationship between  vitamin D status and TSH levels according to thyroid autoantibodies in a population -based health survey in Thail and . METHODS A total of 2582 adults , aged 15 - 98 years , were r and omly selected according to the geographical region from the Thail and 4th National Health Examination Survey sample . By study design , the sexes were equally represented .  Serum levels of 25-hydroxyvitamin D [ 25(OH)D ] , TSH , the thyroid peroxidase antibody ( TPOAb ) , and the thyroglobulin antibody ( TgAb ) were measured in all subjects . RESULTS The mean age was 55.0±0.4 ( SE ) years . In subjects positive for serum TgAb , serum TSH levels were higher , whereas total serum 25(OH)D levels were lower . In addition , the prevalence of vitamin D insufficiency in TgAb-positive subjects was significantly higher than that observed in TPOAb- and TgAb-negative subjects , whether based on cutoff values of 20 or 30 ng/mL : 8.3 % vs. 5.6 % , p<0.05 ; or 47.6 % vs. 42.0 % , p<0.05 , respectively . However , vitamin D status was not associated with positive TPOAb and /or TgAb after controlling for sex and age . To explore the probable interaction between vitamin D status and age on serum TSH , analyses were performed according to age tertiles ; it was found that higher 25(OH)D levels were independently associated with lower TSH , but only in subjects in the lowest age tertile . CONCLUSIONS This population -based study showed that high vitamin D status in younger individuals is associated with low circulating TSH
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 .