Effect of iodine and selenium upon thyroid function. The Relationship Between Iron Status and Thyroid Hormones in Adolescents Living in an Iodine Deficient Area Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. The Association between Selenium and Other Micronutrients and Thyroid Cancer Incidence in the NIH-AARP Diet and Health Study Effect of micronutrient supplement on health and nutritional status of schoolchildren: biochemical status. Minimal impact of excess iodate intake on thyroid hormones and selenium status in older New Zealanders. The relationship between iron status and thyroid hormone concentration in iron-deficient adolescent Iranian girls. A micronutrient-fortified beverage prevents iron deficiency, reduces anemia and improves the hemoglobin concentration of pregnant Tanzanian women. Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency Primary school children from northeast Thailand are not at risk of selenium deficiency. A multimicronutrient-fortified seasoning powder enhances the hemoglobin, zinc, and iodine status of primary school children in North East Thailand: a randomized controlled trial of efficacy. Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study. Serum thyroglobulin and urinary iodine concentration are the most appropriate indicators of iodine status and thyroid function under conditions of increasing iodine supply in schoolchildren in Benin. Randomised trial of iodine intake and thyroid status in preterm infants Effects of administration of iron, iodine and simultaneous iron-plus-iodine on the thyroid hormone profile in iron-deficient adolescent Iranian girls Impact of micronutrient fortification of yoghurt on micronutrient status markers and growth – a randomized double blind controlled trial among school children in Bangladesh Effects of selenomethionine supplementation on selenium status and thyroid hormone concentrations in healthy adults. Vitamin A supplementation in iodine-deficient African children decreases thyrotropin stimulation of the thyroid and reduces the goiter rate. Iron and zinc supplementation improves indicators of vitamin A status of Mexican preschoolers. Redistribution of vitamin A after iron supplementation in Indonesian infants. Multiple micronutrient supplementation increases the growth of Mexican infants. Association of selenium with thyroid volume and echostructure in 35- to 60-year-old French adults. Effect of iron-, iodine-, and beta-carotene-fortified biscuits on the micronutrient status of primary school children: a randomized controlled trial.
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 BACKGROUND Iron may be only one of many nutritional factors that influence thyroid hormone metabolism in iodine-deficient areas . OBJECTIVE To evaluate the effect of iron status on thyroid hormone profile in adolescents living in a mild iodine-deficient area in Turkey . SUBJECTS Three hundred and thirty school-aged children with mean age 14 years were examined . METHODS Free triiodothyronine , free tetraiodothyronine and thyrotropin levels were analyzed by chemiluminescent enzyme immunoassay .  Hemoglobin and mean corpuscular volume were measured with a Hemocounter . Iron and total iron binding capacity concentration were determined by colorimetric photometric methods . Ferritin level was determined by immunoturbidimetry . RESULTS Thyroid hormone levels of the children with anemia were not significantly different compared to children without anemia . No significant correlation was found between thyroid hormones and iron status . CONCLUSION The thyroid hormone profile was not significantly affected in this area . This survey showed no correlation between iron status and thyroid hormone levels BACKGROUND The New Zeal and population has both marginal selenium status and mild iodine deficiency . Adequate intakes of iodine and selenium are required for optimal thyroid function . OBJECTIVE The aim of the study was to determine whether low selenium and iodine status compromises thyroid function in an older New Zeal and population . DESIGN We investigated the effects of selenium and iodine supplementation in a double-blind , r and omized , placebo-controlled trial in 100 Dunedin volunteers aged 60 - 80 y. Participants received 100 microg Se/d as l-selenomethionine , 80 microg I , 100 microg Se + 80 microg I , or placebo for 3 mo . Thyroid-stimulating hormone ( TSH ) , free triiodothyronine ( T(3 ) ) , free thyroxine ( T(4 ) ) , thyroglobulin , plasma selenium , whole-blood glutathione peroxidase ( GPx ) activity , and urinary iodine concentrations ( UICs ) were measured . RESULTS Plasma selenium ( P < 0.0001 ) and whole-blood GPx activity ( P<0.0001 ) increased from baseline to week 12 in the selenium and selenium plus iodine groups in comparison with the placebo group . Median UIC at baseline was 48 microg/L ( interquartile range : 31 - 79 microg/L ) , which is indicative of moderate iodine deficiency . UIC increased in the iodine and selenium plus iodine groups and was significant only for the iodine group ( P = 0.0014 ) . Thyroglobulin concentration decreased by 24 % and 13 % of baseline in the iodine and selenium plus iodine groups in comparison with the placebo group ( P = 0.009 and P = 0.108 , respectively ) . No significant treatment effects were found for TSH , free T(3 ) , free T(4 ) , or ratio of T(3 ) to T(4 ) . CONCLUSIONS Additional selenium improved GPx activity but not the thyroid hormone status of older New Zeal and ers . Iodine supplementation alleviated the moderate iodine deficiency and reduced elevated thyroglobulin concentrations . No synergistic action of selenium and iodine was observed . The trial was registered at www.anzctr.org.au/registry/ as ACTRN012605000368639 Background Selenium is an essential trace element that is important for thyroid hormone metabolism and has antioxidant properties which protect the thyroid gl and from oxidative stress . The association of selenium , as well as intake of other micronutrients , with thyroid cancer is unclear . Methods We evaluated associations of dietary selenium , beta-carotene , calcium , vitamin D , vitamin C , vitamin E , folate , magnesium , and zinc intake with  thyroid cancer  risk in the National Institutes of Health – American Association of Retired Persons Diet and Health Study , a large prospect i ve cohort of 566,398 men and women aged 50–71 years in 1995–1996 . Multivariable-adjusted Cox proportional hazards regression was used to examine associations between dietary intake of micronutrients , assessed using a food frequency question naire , and thyroid cancer cases , ascertained by linkage to state cancer registries and the National Death Index . Results With the exception of vitamin C , which was associated with an increased risk of thyroid cancer ( HRQ5 vs Q1 , 1.34 ; 95 % CI , 1.02–1.76 ; Ptrend , < 0.01 ) , we observed no evidence of an association between quintile of selenium ( HRQ5 vs Q1 , 1.23 ; 95 % CI , 0.92–1.65 ; Ptrend , 0.26 ) or other micronutrient intake and thyroid cancer . Conclusion Our study does not suggest strong evidence for an association between dietary intake of selenium or other micronutrients  and thyroid cancer risk . More studies are needed to clarify the role of selenium and other micronutrients in thyroid carcinogenesis OBJECTIVE We assessed the effect of a daily intake of a micronutrient-fortified beverage for 14 mo on indicators of biochemical status of important micronutrients in schoolchildren . METHODS A double-blind , placebo-controlled , matched-pair , cluster , r and omization study design was used . Biochemical indicators of micronutrient status were evaluated at baseline and at the end of 14 mo on a sub sample in nine matched pairs . Prevalence ( percentage ) of sub clinical deficiency , mean , and mean increments of each indicator were compared between supplemented and placebo groups . RESULTS Extent of inadequacy at baseline was more or less 100 % for folic acid , 65 % for vitamins B2 and B6 , and 55 % for vitamins C and A. Prevalence of anemia among subjects was 55 % , with inadequacy of vitamin B12 being 40 % and that of vitamin D being 30 % . No subject had inadequacy of iodine based on urinary iodine . Supplementation of a micronutrient-enriched beverage for 14 mo significantly improved the status of many of the nutrients . The effect was significant with respect to vitamins A , B2 , and B12 , folic acid , vitamin D , parathyroid hormone , and thyroid-stimulating hormone in children who received the supplement compared with those who received only placebo .  Hemoglobin status improved only in children who had anemia in the supplemented group . CONCLUSIONS Prevalence of multiple sub clinical micronutrient deficiencies are high in middle-income Indian school children . Daily consumption of a micronutrient-enriched beverage had positive effects that were confined to those nutrients that were inadequate at baseline OBJECTIVE Iodine deficiency has re-emerged in New Zeal and , while selenium status has improved . The aim of this study was to investigate the effects of excess iodine intake as io date on thyroid and selenium status . METHODS In a r and omized controlled trial on older people ( mean±s.d . 73±4.8 years ; n=143 ) , two groups received > 50 mg iodine as io date /day for 8 weeks because of supplement formulation error , either with 100 μg selenium ( Se+highI ) or without selenium ( highI ) . Four other groups received 80 μg iodine as io date /day with selenium ( Se+lowI ) or without selenium ( lowI ) , selenium alone ( Se+ ) , or placebo . Thyroid hormones , selenium status , and median urinary iodine concentration ( MUIC ) were compared at weeks 0 , 8 , and 4 weeks post-supplementation . RESULTS MUIC increased nine- and six-fold in Se+highI and highI groups , decreasing to baseline by week 12 . Plasma selenium increased in selenium-supplemented groups ( P<0.001 ) . The level of increase in whole blood glutathione peroxidase ( WBGPx ) in the Se+highI group was smaller than Se+ ( P=0.020 ) and Se+lowI ( P=0.007 ) groups . The decrease in WBGPX in the highI group was greater than other non-selenium-supplemented groups , but differences were not significant . Ten of 43 participants exposed to excess io date showed elevated TSH ( hypothyroidism ) at week 8 . In all but two , TSH had returned to normal by week 12 . In three participants , TSH decreased to < 0.10 mIU/l ( hyperthyroidism ) at week 8 , remaining low at week 12 . CONCLUSIONS Excess io date induced hypothyroidism in some participants and hyperthyroidism in others . Most abnormalities disappeared after 4 weeks . Excess io date reduced WBGPx activity and result ed in smaller increases in WBGPx after selenium supplementation Extensive data from animal and human studies indicate that iron deficiency impairs thyroid metabolism . The aim of this study was to determine thyroid hormone status in iron-deficient adolescent girls . By stepwise r and om sampling from among all public high schools for girls in Lar and its vicinity in southern Iran , 103 out of 431 iron deficient subjects were selected . Urine and serum sample s were collected and assayed for urinary iodine and serum ferritin , iron , total iron binding capacity ( TIBC ) , thyroid stimulating hormone ( TSH ) , thyroxine ( T4 ) , triiodothyronine ( T3 ) , free thyroid hormones ( fT4 and fT3 ) , triiodothyronine resin uptake ( T3RU ) , reverse triiodothyronine ( rT3 ) , selenium and albumin concentrations . Hematological indices for iron status confirmed that all subjects were iron-deficient . There was a significant correlation between T4 and ferritin ( r = 0.52 , P < 0.001 ) and between TSH and ferritin ( r = -0.3 , P < 0.05 ) . Subjects with low serum ferritin had a higher ratio of T3/T4 ( r = -0.42 , P < 0.01 ) . Using stepwise regression analysis , only ferritin contributed significantly to the rT3 concentration ( r = -0.35 , P < 0.01 ) . The results indicate that the degree of iron deficiency may affect thyroid hormone status in iron-deficient adolescent girls Maternal malnutrition continues to be a major contributor to adverse reproductive outcomes in developing countries , despite longst and ing efforts to fortify foods or to distribute medicinal supplements to pregnant women . The objective of this study was to test the effect of a micronutrient-fortified beverage containing 11 micronutrients ( iron , iodine , zinc , vitamin A , vitamin C , niacin , riboflavin , folate , vitamin B-12 , vitamin B-6 and vitamin E ) on the hemoglobin , iron and vitamin A status of pregnant women in Tanzania . A group of 259 pregnant women with gestational ages of 8 to 34 wk were enrolled in a r and omized double-blind controlled trial in which study women received 8 wk of supplementation .  Hemoglobin , ferritin and dried blood spot retinol were measured at baseline and at the end of the supplementation period . The supplement result ed in a 4.16 g/L increase in hemoglobin concentration and a 3 micro g/L increase in ferritin and reduced the risk of anemia and iron deficiency anemia by 51 and 56 % , respectively . The risk of iron deficiency was reduced by 70 % among those who had iron deficiency at baseline and by 92 % among those who had adequate stores . The micronutrient-fortified beverage may be a useful and convenient preventative measure , one that could help improve the nutritional status of women both before and during pregnancy and thereby help avoid some of the potential maternal and fetal consequences of micronutrient deficiencies 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 Selenium has important roles as an antioxidant , in thyroid hormone metabolism , redox reactions , reproduction and immune function , but information on the selenium status of Thai children is limited . We have assessed the selenium status of 515 northeast Thai children ( 259 males ; 256 females ) aged 6 to 13 years from 10 rural schools in Ubon Ratchthani province .  Serum selenium ( n=515 ) was analyzed by Graphite Furnace Atomic Absorption Spectrophotometry and dietary selenium intake by Hydride Generation Absorption Spectrophotometry from one-day duplicate diet composites , from 80 ( 40 females ; 40 males ) r and omly selected children . Inter-relationships between serum selenium and selenium intakes , and other biochemical micronutrient indices were also examined . Mean ( SD ) serum selenium  was 1.46 ( 0.24 ) micro mol/L. Concentrations were not affected by infection or haemoglobinopathies , but were dependent on school ( P < 0.001 ) , sex ( P=0.038 ) , and age group ( P=0.003 ) , with serum zinc as a significant covariate . None of the children had serum selenium concentrations indicative of clinical selenium deficiency ( i.e. < 0.1 micro mol/L ) . Significant correlations existed between serum selenium and serum zinc ( r= 0.216 ; P < 0.001 ) , serum retinol ( r = 0.273 ; P < 0.001 ) , urinary iodine ( r = -0.110 ; P = 0.014 ) , haemoglobin ( r = 0.298 ; P < 0.001 ) , and haematocrit ( r = 0.303 ; P < 0.001 ) . Mean ( SD ) dietary selenium intake was 46 ( 22 ) micro g/d . Children with low serum selenium concentrations had a lower mean selenium intake than those with high serum selenium concentrations ( 38 + /- 17 vs.51 + /- 24 micro g/d ; P < 0.010 ) . In conclusion , there appears to be no risk of selenium deficiency among these northeast Thai children Anemia and co-existing deficiencies of zinc , iron , iodine , and vitamin A occur among children in many developing countries including NE Thail and , probably contributing to impairments in growth , immune competence , and cognition . Sustainable strategies are urgently required to combat these deficiencies . We assessed the efficacy of a micronutrient-fortified seasoning powder served with a school lunch on reducing anemia and improving the micronutrient status of rural NE Thai children . Children ( n = 569 ) aged 5.5 - 13.4y from 10 schools were r and omly assigned to receive a seasoning powder either unfortified or fortified with zinc ( 5 mg ) , iron ( 5 mg ) , vitamin A ( 270 microg ) , and iodine ( 50 microg ) ( per serving ) and incorporated into a school lunch prepared central ly and delivered 5 d/wk for 31 wk . Teachers monitored school lunch consumption . Baseline and final micronutrient status , hemoglobinopathies , and infection or inflammation were assessed from blood and urine sample s. For the primary outcome , anemia ( based on hemoglobin ) , no intervention effect was apparent ( odds ratio : 1.02 95 % CI : 0.69 , 1.51 ) after adjustment for design strata . The odds of zinc ( based on serum zinc ) and urinary iodine deficiency in the fortified group were 0.63 ( 0.42 , 0.94 ) and 0.52 ( 0.38 , 0.71 ) times those in the unfortified group , respectively . Fortification had no effect on serum retinol ( 0.61 : 0.25,1.51 ) , ferritin ( 1.12 : 0.43 , 2.96 ) , or mean red cell volume ( 1.16 : 0.82 , 1.64 ) . Therefore , a micronutrient-fortified seasoning powder is a promising vehicle for improving zinc , iodine , and hemoglobin status , and its potential for incorporation into lunch programs in day care centers and schools in NE Thail and warrants investigation BACKGROUND Iodine is required for the production of thyroid hormones , which are necessary for normal brain development and cognition . Although several r and omized trials examined the effect of iodine supplementation on cognitive performance in schoolchildren , the results were equivocal . OBJECTIVE We aim ed to ascertain whether providing iodized oil to iodine-deficient children would affect their cognitive and motor performance . DESIGN In a double-blind intervention trial , 10 - 12-y-old children ( n = 310 ) in primary schools in rural southeastern Albania were r and omly assigned to receive 400 mg I ( as oral iodized oil ) or placebo . We measured urinary iodine ( UI ) , thyroid-stimulating hormone ( TSH ) , and total thyroxine ( TT4 ) concentrations and thyroid gl and volume ( by ultrasound ) . The children were given a battery of 7 cognitive and motor tests , which included measures of information processing , working memory , visual problem solving , visual search , and fine motor skills .  Thyroid ultrasound and the biochemical and psychological tests were repeated after 24 wk . RESULTS At baseline , the children 's median UI concentration was 43 microg/L ; 87 % were goitrous , and nearly one-third had low concentrations of circulating TT4 . Treatment with iodine markedly improved iodine and thyroid status : at 24 wk , median UI in the treated group was 172 microg/L , mean TT4 was approximately 40 % higher , and the prevalence of hypothyroxinemia was < 1 % . In the placebo group after the intervention , these variables did not differ significantly from baseline . Compared with placebo , iodine treatment significantly improved performance on 4 of 7 tests : rapid target marking , symbol search , rapid object naming , and Raven 's Coloured Progressive Matrices ( P < 0.0001 ) . CONCLUSION Information processing , fine motor skills , and visual problem solving are improved by iodine repletion in moderately iodine-deficient schoolchildren Iodine deficiency control programs have greatly reduced iodine deficiency disorders worldwide . For monitoring changes in iodine status , different indicators may be used . The aim of this study was to evaluate the suitability of indicators of iodine status and thyroid function , thyroglobulin ( Tg ) , thyroid-stimulating hormone ( TSH ) and free thyroxine ( FT4 ) in serum , thyroid volume and urinary iodine concentration , in iodine-deficient schoolchildren under conditions of increasing iodine supply . The study was established as a double-blind , placebo-controlled oral administration of a single dose of iodized oil to schoolchildren ( 7 - 10 y old ) , living in an iodine-deficient area of Benin , with an observation period of 10 mo . However , 3 - 4 mo after supplementation , iodized salt became available in the area . The study population therefore comprised an iodized oil-supplemented group  and a nonsupplemented group  , both of which had variable , uncontrolled intakes of iodized salt during the last 6 mo of the study . Initial mean serum concentrations of TSH and FT4 were within the normal range , whereas serum Tg concentration , urinary iodine concentration and thyroid volume were indicative of moderate-to-severe iodine deficiency . At the end of the study , all indicators had improved significantly , except thyroid volume , which had decreased only in the supplemented group . The supplemented group also still had significantly lower serum Tg and higher urinary iodine concentrations than the nonsupplemented group . Serum Tg and urinary iodine concentrations are the indicators most influenced by a changing iodine supply . Current normal reference ranges of serum concentrations of TSH and FT4 are too wide for detecting iodine deficiency in this age group BACKGROUND Low levels of circulating thyroid hormones have been associated with poorer general and neurodevelopmental outcome in preterm babies and it has been speculated that the association is causal . Low levels of circulating thyroid hormone have been reported after inadequate intake of iodine in preterm infants being fed milk formula . AIM To investigate whether increased iodine intake from supplemented preterm formula would improve thyroid hormone levels in preterm babies ( this study ) and hence improve neurodevelopmental status ( planned subsequent study ) . METHOD A total of 121 preterm infants were entered into a r and omised controlled trial of st and ard ( 68 μg/l ) versus increased ( 272 μg/l ) iodine in preterm formula . RESULTS The two groups were comparable at recruitment . No evidence of an effect of the intervention on thyroid hormone levels was seen up to 41 weeks after conception . CONCLUSION Calls for increased iodine content of preterm infant formulas are not justified by this study . Key message Increasing milk iodine content in line with the latest recommendations for preterm babies had no effect on thyroid hormone levels in the perinatal Objective : To investigate whether iron supplementation can improve thyroid hormone function in iron-deficient adolescent girls . Design : A double-blind r and omized intervention study . Setting : The study was performed from 2002 through 2003 in the Islamic Republic of Iran . Subjects:103 iron-deficient non-anaemic girls who fulfilled all inclusion criteria were included , and 94 subjects successfully completed the study . Interventions : Patients were r and omly assigned to one of four groups and treated with a single oral dose of 190 mg iodine plus 300 mg ferrous sulphate 5 times/week ( n=24 ) , 300 mg ferrous sulphate 5 times/week ( n=23 ) , a single oral dose of 190 mg iodine ( n=25 ) , or a placebo ( n=22 ) for 12 weeks . Results : All groups were comparable at baseline . After the intervention , there was a significant increase in ferritin and transferrin saturation in the iron+iodine group ( 17.6 vs 8.7 μg/dl , and 18.8 vs 7.2 % , respectively , P<0.001 for both ) and in the iron group ( P<0.001 for both ) . Urinary iodine doubled in the iron+iodine group and in the iodine group ( P<0.001 for both ) . Thyroid indices tT4 , tT3 and T3RU increased and reverse RT3 decreased in the iron+iodine group ( 10 vs 8.9 μg/dl , P < 0.001 ; 143 vs 138 μg/dl , P<0.05 ; 32.3 vs 28.4 % , P<0.001 and 24.8 vs 44.2 ng/dl , P<0.001 , respectively ) and in the iron group . These two groups did not differ for any of the four indices , but both differed significantly from the iodine and placebo groups . Conclusions : Our results indicate that improvement of iron status was accompanied by an improvement in some indices of thyroid hormones . Sponsorship : This study was supported by the Dean of Research Affairs of the Tehran University of Medical Sciences Background Interventions providing foods fortified with multiple micronutrients can be a cost-effective and sustainable strategy to improve micronutrient status and physical growth of school children . We evaluated the effect of micronutrient-fortified yoghurt on the biochemical status of important micronutrients ( iron , zinc , iodine , vitamin A ) as well as growth indicators among school children in Bogra district of Bangladesh . Methods In a double-masked r and omized controlled trial ( RCT ) conducted in 4 primary schools , 1010 children from classes 1–4 ( age 6–9 years ) were r and omly allocated to receive either micronutrient fortified yoghurt ( FY , n = 501 ) or non-fortified yoghurt ( NFY , n = 509 ) . For one year , children were fed with 60 g yoghurt everyday providing 30 % RDA for iron , zinc , iodine and vitamin A.  Anthropometric measurements and blood/urine sample s were collected at base- , mid- and end-line . All children ( FY , n = 278 , NFY , n = 293 ) consenting for the end-line blood sample were included in the present analyses . Results Both groups were comparable at baseline for socio-economic status variables , micronutrient status markers and anthropometry measures . Compliance was similar in both the groups . At baseline 53.4 % of the population was anemic ; 2.1 % was iron deficient ( ferritin < 15.0 μg/L and TfR > 8.3 mg/L ) . Children in the FY group showed improvement in Hb ( mean difference : 1.5 ; 95 % CI : 0.4 - 2.5 ; p = 0.006 ) as compared to NFY group . Retinol binding protein ( mean diff : 0.05 ; 95 % CI : 0.002 - 0.09 ; p = 0.04 ) and iodine levels ( mean difference : 39.87 ; 95 % CI : 20.39 - 59.35 ; p < 0.001 ) decreased between base and end-line but the decrease was significantly less in the FY group . Compared to NFY , the FY group had better height gain velocity ( mean diff : 0.32 ; 95 % CI : 0.05 - 0.60 ; p = 0.02 ) and height-for-age z-scores ( mean diff : 0.18 ; 95 % CI : 0.02 - 0.33 ; p = 0.03 ) . There was no difference in weight gain velocity , weight-for-age z-scores or Body Mass Index z-scores . Conclusion In the absence of iron deficiency at baseline the impact on iron status would not be expected to be observed and hence can not be evaluated . Improved Hb concentrations in the absence of a change in iron status suggest improved utilization of iron possibly due to vitamin A and zinc availability . Fortification improved height gain without affecting weight gain . Trial registration Clinical Trial.gov : BACKGROUND Selenium , a potential cancer prevention agent currently being tested against prostate cancer in the Selenium and Vitamin E Cancer Prevention Trial ( SELECT ) , plays an integral role in thyroid metabolism . The effects of long-term selenium supplementation on thyroid hormone concentrations are unknown . OBJECTIVE The objective was to investigate the effects of long-term selenium supplementation on thyroid hormone concentrations . DESIGN Twenty-eight healthy adults took 200 microg selenomethionine/d for 28 mo . The thyroid hormones triiodothyronine ( T3 ) , thyroxine ( T4 ) , and thyrotropin ( TSH ) were measured in plasma for 4 mo before supplementation and quarterly during supplementation . The assay methods were changed mid study ; the results of the 2 methods were not comparable . Therefore , one analysis was conducted based on the results of the first method , and a second analysis was based on all of the data , adjusted for the change . Serial data collection permitted a test for trends rather than simply a difference between initial and final values . RESULTS By 9 mo , mean ( + /-SEM ) plasma selenium concentrations had increased from 1.78 + /- 0.07 micromol/L at baseline to 2.85 + /- 0.11 micromol/L for men and from 1.64 + /- 0.04 to 3.32 + /- 0.1.2 micromol/L for women . T3 concentrations in men increased 5 % per year ( P = 0.01 ) . T4 and TSH concentrations were unchanged . CONCLUSIONS Selenium supplementation produced no clinical ly significant changes in thyroid hormone concentrations . A small but statistically significant increase in T3 concentrations was noted in men , with no corresponding decreases in TSH . A subset of SELECT subjects might be monitored periodically for changes during long-term selenium supplementation BACKGROUND Vitamin A ( VA ) deficiency ( VAD ) and iodine deficiency ( ID ) often coexist in children in Africa . VAD may affect thyroid function and the response to iodine prophylaxis . OBJECTIVE The aim was to investigate the effects of supplementation with iodine or VA alone , and in combination , in children with concurrent VAD and ID . DESIGN A 6-mo r and omized , double-blind , 2 x 2 intervention trial was conducted in 5 - 14 y-old South African children ( n = 404 ) , who , on average , had mild-to-moderate VAD and ID . At baseline and after 3 mo , children received 1 ) iodine ( 191 mg I as oral iodized oil ) + placebo ( IS group ) , 2 ) VA ( 200000 IU VA as retinyl palmitate ) + placebo ( VAS group ) , 3 ) both iodine and VA ( IS+VAS group ) , or 4 ) placebo . At baseline , 3 mo , and 6 mo , urinary iodine ( UI ) , thyroid volume , thyrotropin ( thyroid-stimulating hormone ; TSH ) , total thyroxine ( TT(4 ) ) , thyroglobulin , serum retinol ( SR ) , and retinol-binding protein ( RBP ) were measured . RESULTS SR and RBP increased significantly with VA supplementation ( P < 0.05 ) . For UI , SR , and RBP , there were no significant treatment interactions between iodine and vitamin A. The 3-factor and all three 2-factor interactions were significant for thyroid volume , TSH , and thyroglobulin ( P < 0.001 ) , whereas none of these interactions were significant for TT(4 ) . There was a clear effect of VAS without IS on TSH , thyroglobulin , and thyroid volume ; all 3 variables decreased significantly ( P < 0.05 ) . CONCLUSIONS Iodine prophylaxis is effective in controlling ID in areas of poor vitamin A status . VA supplements are effective in treating VAD in areas of mild ID and have an additional benefit-through suppression of the pituitary TSHbeta gene , VAS can decrease excess TSH stimulation of the thyroid and thereby reduce the risk of goiter and its sequelae BACKGROUND The coexistence of multiple micronutrient deficiencies is a widespread public health problem in many regions of the world . Interactions between zinc deficiency and vitamin A metabolism have been reported but no longitudinal studies have evaluated the effect of iron deficiency on vitamin A. OBJECTIVE The objective of this study was to investigate the effect of supplementation with iron , zinc , or both on vitamin A and its metabolically related proteins retinol binding protein ( RBP ) and transthyretin . DESIGN The study was a longitudinal , double-blind , placebo-controlled trial in which 219 rural Mexican children aged 18 - 36 mo were r and omly assigned to receive 20 mg Zn/d , 20 mg Fe/d , 20 mg Zn/d plus 20 mg Fe/d , or placebo . RESULTS Six months after supplementation , plasma retinol increased in all supplemented groups . Compared with placebo , zinc supplementation was associated with significantly higher plasma retinol and transthyretin but the increase in RBP was not significant . Iron supplementation significantly increased plasma retinol , RBP , and transthyretin . Supplementation with zinc plus iron significantly increased plasma retinol but not RBP or transthyretin .  Children deficient in zinc , iron , or vitamin A ( as indicated by nutrient plasma concentration ) at the beginning of the study had a significantly greater increase in retinol than did children with adequate nutrient status . CONCLUSIONS Supplementation with zinc , iron , or both improved indicators of vitamin A status . The results of this study agree with previous observations of a metabolic interaction between zinc and vitamin A and suggest an interaction between iron and vitamin A metabolism BACKGROUND Deficiencies of iron and vitamin A are prevalent worldwide . Single-micronutrient supplementation is widely used to combat these deficiencies . However , micronutrient deficiencies often occur concurrently , and there are many interactions between micronutrients . OBJECTIVE This study investigated interactions among 3 important micronutrients -- iron , vitamin A , and zinc -- when they are given as supplements . DESIGN In a r and omized , double-blind , placebo-controlled supplementation trial , 387 Indonesian infants aged 4 mo were supplemented 5 d/wk for 6 mo with 10 mg Fe , 10 mg Zn , 2.4 mg beta-carotene , 10 mg each of Fe and Zn , 10 mg Zn + 2.4 mg beta-carotene , or placebo . Complete data on micronutrient status , including hemoglobin , ferritin , retinol , zinc , and the modified relative dose response ( a measure of liver retinol stores ) , were available from 256 infants at the end of the study . RESULTS Iron-supplemented infants had significantly lower plasma retinol concentrations and a significantly higher prevalence of vitamin A deficiency , as defined by a plasma retinol concentration < 0.70 micromol/L , than did the non-supplemented infants . In contrast , the modified relative dose response of the iron-supplemented infants indicated greater liver stores of vitamin A.  Iron supplementation improved iron status , and zinc supplementation improved zinc status , but beta-carotene supplementation did not significantly improve vitamin A status . CONCLUSIONS In this study , iron supplementation in infants with marginal vitamin A status led to lower plasma vitamin A concentrations and simultaneously to greater vitamin A liver stores . This implies a redistribution of retinol after iron supplementation , which might induce vitamin A deficiency . Therefore , iron supplementation in infants should be accompanied by measures to improve vitamin A status BACKGROUND The role of single micronutrient deficiencies in the etiology of growth retardation has recently gained attention . However , because multiple micronutrient deficiencies are common in children in developing countries , it is possible that more than one micronutrient may limit growth and , hence , the correction of a single deficiency may not be enough to improve growth substantially . OBJECTIVE The objective was to evaluate the effect of multiple micronutrient supplementation on the growth of children aged 8 - 14 mo whose diets were poor in several micronutrients . DESIGN Children were r and omly assigned to 1 of 2 groups . One group received a multiple micronutrient supplement containing the recommended dietary allowance ( RDA ) or 1.5 times the RDA of vitamins A , D , E , K , C , B-1 , B-6 , B-12 , riboflavin , niacin , biotin , folic acid , and pantothenic acid , and iron , zinc , iodine , copper , manganese , and selenium . The other group received a placebo . Supplements were administered 6 d/wk for an average of 12.2 mo . Body length was measured at baseline and monthly thereafter until the end of supplementation . RESULTS Supplemented infants initially aged < 12 mo had significantly greater length gains than did the placebo group , with a difference of 8.2 mm ( length-for-age z score : 0.3 ) at the end of supplementation . In contrast , differences in length gains between the supplemented and placebo groups initially aged > or = 12 mo were not significant . CONCLUSIONS Micronutrient deficiencies limited the growth of the Mexican infants studied . Improving micronutrient intakes should be a component of interventions to promote growth in infants living in setting s where micronutrient intakes are inadequate OBJECTIVE To investigate the relationship between selenium status , thyroid Volume and gl and echostructure . DESIGN Cross-sectional . METHODS In 792 men ( 45 - 60 Years ) and 1108 women ( 35 - 60 Years ) from the SU.VI.MAX study , thyroid Volume and gl and echostructure were determined ultrasonographically . At baseline , thyrotropin , free thyroxine , selenium , zinc , alpha-tocopherol , beta-carotene , retinol , urinary iodine and thiocyanate concentrations were measured . Alcohol consumption , smoking , and menopausal status were assessed by a question naire . A stepwise linear and a logistic regression model were used , adjusting for antioxidant vitamins , trace elements status and age . RESULTS In women , there was an inverse association between selenium status and thyroid Volume ( P=0.003 ) . A protective effect of selenium against goiter ( odds ratio (OR)=0.07 , 95 % confidence interval (CI)=0.008 - 0.6 ) and thyroid tIssue damage ( OR=0.2 , 95 % CI=0.06 - 0.7 ) was observed . There was no evidence of an association between menopausal status and other antioxidant elements , thyroid Volume or thyroid hypoechogenicity . Smoking , but not alcohol consumption , was associated with an increased risk of thyroid enlargement in women ( OR=3.94 , 95 % CI=1.64 - 9.48 ) . No association between thyroid Volume , thyroid structure or selenium was found in men . CONCLUSION Our findings suggest that selenium may protect against goiter . Selenium was related to thyroid echostructure , suggesting it may also protect against autoimmune thyroid disease BACKGROUND Deficiencies of iron , iodine , and vitamin A are prevalent worldwide and can affect the mental development and learning ability of schoolchildren . OBJECTIVE The aim of this study was to determine the effect of micronutrient-fortified biscuits on the micronutrient status of primary school children . DESIGN Micronutrient status was assessed in 115 children aged 6 - 11 y before and after consumption of biscuits ( fortified with iron , iodine , and beta-carotene ) for 43 wk over a 12-mo period and was compared with that in a control group ( n = 113 ) who consumed nonfortified biscuits .  Cognitive function , growth , and morbidity were assessed as secondary outcomes . RESULTS There was a significant between-group treatment effect on serum retinol , serum ferritin , serum iron , transferrin saturation , and urinary iodine ( P < 0.0001 ) and in hemoglobin and hematocrit ( P < 0.05 ) . The prevalence of low serum retinol concentrations ( < 0.70 micromol/L ) decreased from 39.1 % to 12.2 % , of low serum ferritin concentrations ( < 20 microg/L ) from 27.8 % to 13.9 % , of anemia ( hemoglobin < 120 g/L ) from 29.6 % to 15.6 % , and of low urinary iodine concentrations ( < 100 microg/L ) from 97.5 % to 5.4 % . There was a significant between-group treatment effect ( P < 0.05 ) in cognitive function with the digit span forward task ( short-term memory ) . Fewer school days were missed in the intervention than in the control group because of respiratory- ( P = 0.097 ) and diarrhea-related ( P = 0.013 ) illnesses . The intervention had no effect on anthropometric status [ corrected ] . CONCLUSIONS Fortified biscuits result ed in a significant improvement in the micronutrient status of primary school children from a poor rural community and also appeared to have a favorable effect on morbidity and cognitive function [ corrected ]
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 .