Selenium is central to thyroid hormone metabolism because the three iodothyronine deiodinases (DIO1, DIO2, DIO3) are selenoproteins. Each enzyme has a selenocysteine residue in its active site, and this selenium atom is what actually participates in the reductive deiodination reaction that removes iodine atoms from thyroid hormones.
The deiodinases sit mainly in liver, kidney, brain, muscle, placenta, brown fat, and other peripheral tissues, where they convert T4 to active T3 or inactivate T4/T3 to rT3/T2. Selenium deficiency lowers D1 and D2 activity, so tissues get less T3 even if serum T4 looks normal, while D3 patterns can also shift, disturbing local thyroid signaling. At the other extreme, chronically high selenium intake can alter selenoprotein expression, disturb deiodinase activity, and is associated with U shaped relationships to thyroid status and systemic outcomes, so both low and high selenium can distort peripheral thyroid hormone metabolism.
There are many studies exploring the relation between fluoride and selenium, as well as iodine and selenium. Below is a short list of relevant publications.
Selenium, Iodine & Fluoride
Liu GY, Chai CY, Kang SL - "Progress in research of biologically relevant effects of fluoride, iodine and selenium" Shanghai Animal Husbandry and Veterinary Medicine 5:9-10 (2001) PFPC Library
Lu HZ, Du FP, Li XD - "Fluorine, iodine, selenium and human health" University Chemistry 25(S1):93-96 (2010) PFPC Library
Shen SY, Zhang XL, Xu XL, et al - "Effect of iodine and selenium on learning and memory impairment induced by fluorosis and blood biochemical indices in rats" Occupation and Health 20(1):6-8 (2004) PFPC Library
Xu XL, Shen SY, Zhang ZG, et al - "Protective effects of iodine and selenium on fluoride induced brain injury in mice" Journal of Health Toxicology 16(2):94-95 (2002) PFPC Library
Xu XL, Zhang ZG, Shen SY, et al - "Effects of selenium and iodine on fluoride effects on brain function in mice" Proceedings of the Ninth National Conference of Psychology (China) (2001) PFPC Library
Zhang Z, Xu XL, Shen X, et al - "Effects of iodine and selenium on the impairments of mitochondrion induced by fluorine in renal cells of mice" Journal of Zhejiang Normal University (Natural Science Edition) 25(4):395-397 (2002) PFPC Library
Zheng ZX, Shao HY, Li L, Liu TX, Wu HZ - "Iodine, fluorine and selenium contents in drinking water and their correlation with urinary iodine in primary school children in a county of Ningxia" Ningxia Medical Journal 33(2):128-130 (2011) PFPC Library
Selenium & Fluoride
Bian JC, Xian SM, Ye P, Guan SF, Liu Y, Ji QX - "Changes in fluoride and antioxidant enzymes and the effects of selenium in rats with chronic fluorosis" Acta Nutrimenta Sinica 19(1):43-49 (1997) PFPC Library
Charitha GS, Sudhakar K, Reddy KP - "Protective effects of selenium against sodium fluoride induced behavioral, anti-oxidant and neurohistological alterations in Wistar rats" Biosci Biotechnol Res Asia 15(2):475-484 (2018)In rats with chronic fluorosis, LPO levels in serum, liver, and kidney increased continuously throughout the course of the experiment. GSH-Px, SOD, and GSH showed an initial increase in the early stage of fluorosis, followed by significant decreases in the middle and late stages. These findings indicate that under high fluoride exposure, antioxidant enzymes and antioxidant substances shift from a compensatory rise to depletion, leading to tissue damage due to lipid peroxidation and ultimately to disturbances of free radical metabolism...After selenium supplementation, urinary fluoride excretion increased and serum fluoride levels decreased compared with non-selenium fluorosis groups. Activities of GSH-Px and SOD and the level of GSH increased, while LPO levels decreased.
https://doi.org/10.13005/BBRA/2652
Chen L, Wang Y, Yang W, Tian M – "Effect of different selenium levels on tooth germ development in rats with fluorosis" Journal of Oral Science Research 28(5):417-419,422 (2012)
Chouhan S, Kushwaha P, Kaul R, Flora SJS - "Co-administration of selenium but not iron prevents fluoride toxicity in rats" Biomed Prev Nutr 3(2):113-120 (2013)[Objective] To investigate the effects of different selenium levels on tooth germ development in rats with fluorosis.
[Methods] Sixty male SD rats were randomly divided into six groups. The control group received a normal diet and distilled water. The experimental groups received distilled water containing 45 mg/L fluoride (F⁻). The fluoride group received a normal diet. Fluoride-selenium group 1 received a diet containing 1.37 mg/kg selenium, fluoride-selenium group 2 received 1.6 mg/kg selenium, fluoride-selenium group 3 received 2.3 mg/kg selenium, and fluoride-selenium group 4 received 4.0 mg/kg selenium. After 8 weeks of feeding, the rats were sacrificed by decapitation. Immunohistochemistry was used to detect the expression of Smad3 and Shh in secretory ameloblasts.
[Results] Smad3 and Shh were positively expressed in ameloblasts in the control group. Their expression in the fluoride group was significantly reduced compared with the control group. In the fluoride-selenium groups, Smad3 and Shh expression was higher than in the fluoride group, with the strongest expression observed in fluoride-selenium group 3 (2.3 mg/kg selenium).
[Conclusion] The mechanism by which selenium antagonizes fluoride poisoning may be related to its regulation of the signal transduction factors Smad3 and Shh that control tooth germ development, with 2.3 mg/kg selenium showing the most pronounced protective effect.
https://doi.org/10.1016/j.bionut.2012.08.007
Du X, Li G, Cheng X, Liu Y, Ma C, Zheng L, He Z, Zhang W, Bai Z - "Effects of selenium on urinary fluoride and lipid peroxide content in brain and kidney tissues of fluoride-poisoned rats" Guangdong Trace Elements Science (4):15-19 (1994) PFPC Library
El-Megharbel SM, Al-Salmi FA, Refat MS, Hamza RZ - "Selenium/chitosan-folic acid metal complex ameliorates hepatic damage and oxidative injury in male rats exposed to sodium fluoride" Crystals 11(11):1354 (2021)
https://doi.org/10.3390/cryst11111354
Feng P, Wei JR, Zhang ZG – "Intervention of selenium on chronic fluorosis-induced injury of blood antioxidant capacity in rats" Biol Trace Elem Res 144(1-3):1024-1031 (2011)
https://doi.org/10.1007/s12011-011-9087-9
Feng P, Wei JR, Zhang ZG – "Influence of selenium and fluoride on blood antioxidant capacity of rats" Exp Toxicol Pathol 64(6):565-568 (2012)
https://doi.org/10.1016/j.etp.2010.11.014
Gao JP, Wang Y, Xu G, Wei J, Chang K, Tian X, Liu M, Yan X, Huo M, Song G – "Selenium attenuates apoptosis and p-AMPK expressions in fluoride-induced NRK-52E cells" Environ Sci Pollut Res Int 26(15):15685-15697 (2019)
https://doi.org/10.1007/s11356-019-04855-2
Gao JP, Tian XL, Yan XR, Wang Y, Wei JN, Wang XT, Yan XY, Song GH – "Selenium exerts protective effects against fluoride-induced apoptosis and oxidative stress and altered the expression of Bcl-2/Caspase family" Biol Trace Elem Res 199(2):682-692 (2021)
https://doi.org/10.1007/s12011-020-02185-w
Hamza RZ, Al-Harbi MS - "Sodium fluoride induced neurotoxicity and possible antioxidant role of selenium and curcumin in male mice" Biosci Biotechnol Res Asia 11(1):81-87 (2014)
https://doi.org/10.13005/bbra/1158
Hu A, Liu X, Qin Y - "Effects of trace amounts of F- on thyroid in mice" Journal of Bengbu Medical College (4)(2008) (In Chinese)
http://poisonfluoride.com/phpBB3/viewtopic.php?p=678
Hu Y, Yan Z, He Y, Li Y, Li M, Li Y, Zhang D, Zhao Y, Ommati MM, Wang J, Huo M, Wang J - "Ameliorative effects of different doses of selenium against fluoride-triggered apoptosis and oxidative stress-mediated renal injury in rats through the activation of Nrf2/HO-1/NQO1 signaling pathway" Food Chem Toxicol 174:113647 (2023)
https://doi.org/10.1016/j.fct.2023.113647
Huang W, Guan LP, Xu SW, Cui YL, Li S - "Effect of selenium on apoptosis of spleen cells, T-cell subset of fluorosis chicken" Chinese Journal of Endemiology 29(2):142-145 (2010)
https://doi.org/10.3760/cma.j.issn.1000 ... 010.02.009
Ju H, Chen S, Xue Y, Zhang X, Wang Y - "The role of Nrf2 pathway in alleviating fluorine-induced apoptosis by different selenium sources in the chicken duodenum and jejunum" Ecotoxicol Environ Saf 224:112708 (2021)
https://doi.org/10.1016/j.ecoenv.2021.112708
Li W, Dong S, Chen Q, Chen C, Dong Z - "Selenium may suppress peripheral blood mononuclear cell apoptosis by modulating hSP70 and regulate levels of Sirt1 through reproductive hormone secretion and oxidant stress in women suffering fluorosis" Eur J Pharmacol 878:173098 (2020)
https://doi.org/10.1016/j.ejphar.2020.173098
Li J, Ren F, Li X, Qiu Z, Zhang Z - "Selenium exerts protective effects against fluoride-induced apoptosis and oxidative stress and alleviates cardiac injury via regulation of endoplasmic reticulum stress in mice" Eur J Pharmacol 882:173279 (2020)
https://doi.org/10.1016/j.ejphar.2020.173279
Lu CH, Guo XW, Bian JC, Ye P, Xian S, Liu Y, Ji QX - "Experimental Study on the Effect of High Fluoride and Selenium Supplementation on Rat Thyroid" Chinese Journal of Endemic Diseases" (2):105-107 (1998)
http://yuxiqbs.cqvip.com/Qikan/Article/ ... arch_Index
Lu C, Bian J, Ye P, Xian S, Liu Y, Ji Q - "Effects of excessive fluoride and selenium on pituitary gland, thyroid gland and parathyroid gland in rats" Chinese Journal of Control of Endemic Disease :18-20 (1996)The changes of urinary fluoride, thyroid tissue structure and hormones in 60 rats drinking 30mg/L or 50mg/L high-fluoride water and supplemented with selenium were observed. The results showed that urinary fluoride increased with the prolonged drinking time of high-fluoride water, and selenium supplementation could increase urinary fluoride excretion in the early stage; the thyroid follicular epithelium proliferated actively and free thyroid hormone increased in the early stage; the thyroid follicular epithelium degenerated in the later stage, and the levels of FT3 and T4 decreased. This suggests that high fluoride excites the thyroid gland in the early stage, and the thyroid function is highly compensated, and the thyroid function is suppressed in the later stage, resulting in hypothyroidism; the changes of fluoride and thyroid tissue and function are closely related to the time of fluoride intake.
Miao K, Zhang L, Yang S, Qian W, Zhang Z - "Intervention of selenium on apoptosis and Fas/FasL expressions in the liver of fluoride-exposed rats" Environ Toxicol Pharmacol 36(3):913-920 (2013)
https://doi.org/10.1016/j.etap.2013.08.003
Qian W, Miao K, Li T, Zhang Z - "Effect of selenium on fluoride-induced changes in synaptic plasticity in rat hippocampus" Biol Trace Elem Res 155(2):253-260 (2013)
https://doi.org/10.1007/s12011-013-9773-x
Radovanović TB, Jović S, Pećinar I, Ćupić Ž, Jovanović M, Borković-Mitić S, Despotović N, Gavrić JP, Gavrić M, Pavlović SZ - "Genotoxicity of fluoride subacute exposure in rats and selenium intervention" Chemosphere 266:128978 (2021)
https://doi.org/10.1016/j.chemosphere.2020.128978
Reddy KP, Sailaja G, Krishnaiah C - "Protective effects of selenium on fluoride induced alterations in certain enzymes in brain of mice" J Environ Biol 30(5 Suppl):859-864 (2009)
Tao N, Li L, Chen Q, Sun Z, Yang Q, Cao D, Zhao X, Zeng F, Liu J - "Association between antioxidant nutrients, oxidative stress-related gene polymorphism and skeletal fluorosis in Guizhou, China" Front Public Health 10:849173 (2022)
https://doi.org/10.3389/fpubh.2022.849173
Wang T, Li H, Li Y, Li M, Zhao H, Zhang W, Zhao T, Wang Y, Wang J, Wang J – "Selenomethionine supplementation mitigates fluoride-induced liver apoptosis and inflammatory reactions by blocking Parkin-mediated mitophagy in mice" Science of the Total Environment 951:175458 (2024)
https://doi.org/10.1016/j.scitotenv.2024.175458
Wang YX, Xiao X, Zhan XA - "Antagonistic effects of different selenium sources on growth inhibition, oxidative damage, and apoptosis induced by fluorine in broilers" Poult Sci 97(9):3207-3217 (2018)
https://doi.org/10.3382/ps/pey192
Wang Y, Chen L, Tang Y, Chen J – "Effect of different selenium levels on rats with fluorosis" Journal of Oral Science Research 28(10):987-990,993 (2012)
Wei JR, Feng P, Zhang ZG – "Effect of combined exposure to fluoride and selenium on biochemical functions of the testis of male rats" Journal of Zhejiang Normal University (Natural Science Edition) 34(1):86-90 (2011)[Objective] To investigate the effects of different selenium levels on fluorosis in rats.
[Methods] Sixty male SD rats were randomly divided into six groups. The control group received a normal diet and distilled water. The experimental groups received distilled water containing 45 mg/L fluoride (F⁻). The fluoride group received a normal diet. The four fluoride-selenium groups received diets containing selenium at 1.37 mg/kg, 1.6 mg/kg, 2.3 mg/kg, or 4.0 mg/kg, respectively. The experiment lasted for 2 months. General condition and body weight of the rats were recorded weekly. Twenty-four hour urine was collected to determine urinary fluoride content and to grade dental fluorosis. At the end of the first and second month, tail blood was collected from 8 rats in each group to measure serum glutathione peroxidase (GSH-PX) and catalase (CAT) activities.
[Results] Compared with the control group, the experimental groups showed slower body-weight gain, higher urinary fluoride levels, and decreased serum GSH-PX and CAT activities. Compared with the fluoride group, all four fluoride-selenium groups showed faster body-weight gain, higher urinary fluoride levels, milder dental fluorosis, and increased serum GSH-PX and CAT activities.
[Conclusion] Appropriate selenium intake can correct free-radical metabolism disorders and exerts an antagonistic effect on high-fluoride exposure, whereas excessive selenium has a synergistic effect with fluoride. Among the tested doses, 2.3 mg/kg selenium provided the most effective protection against fluorosis.
Yang N, Wang J, Li L - "Examining the Correlational Interaction of Environmental Fluoride and Selenium and Its Impact on Dental Fluorosis in Coal-Burning Regions of Southwest China" Toxics 13(11):940 (2025)[Objective] To investigate the antagonistic effect of selenium on male reproductive toxicity induced by chronic fluorosis in male rats.
[Methods] Male SD rats were given deionized water supplemented with sodium fluoride (NaF) and/or sodium selenite (Na₂SeO₃) for 6 months. Body weight, testis and epididymis weights, and their organ coefficients were measured and calculated. The activities of lactate dehydrogenase (LDH), acid phosphatase (ACP), alkaline phosphatase (AKP), Na⁺/K⁺-ATPase, Mg²⁺-ATPase and Ca²⁺-ATPase in testicular tissue were determined.
[Results] (1) Compared with the control group, body weight was significantly increased (P < 0.05) in the fluoride plus low-dose selenium group and the fluoride plus medium-dose selenium group. (2) LDH activity was significantly decreased (P < 0.05) in the fluoride group compared with the control group, and significantly increased (P < 0.05) in the medium-dose selenium group, high-dose selenium group and fluoride plus high-dose selenium group compared with the fluoride group. ACP activity was significantly altered (P < 0.05) in the fluoride group and in the fluoride plus medium-dose selenium group compared with the control group. AKP activity also showed significant changes (P < 0.05) in the fluoride group compared with the control group. (3) Significant differences (P < 0.05) in Na⁺/K⁺-ATPase activity were observed among three of the exposure groups. Ca²⁺-ATPase activity in the medium-dose selenium group and in the fluoride plus high-dose selenium group differed significantly (P < 0.05) from that of the control group.
[Conclusion] Fluoride exposure caused reproductive toxicity in male rats, and appropriate selenium intake antagonized the reproductive toxicity induced by fluoride.
https://doi.org/10.3390/toxics13110940
Ecological analysis from coal-burning regions suggesting that higher environmental selenium may mitigate, and co-exposure patterns may modify, the severity of dental fluorosis linked to elevated fluoride.
Yu RA, Xia T, Wang AG, Chen XM - "Effects of selenium and zinc on renal oxidative stress and apoptosis induced by fluoride in rats" Biomed Environ Sci 19(6):439-444 (2006)
Yu Q, Zuo N, Jia HY, Li JM, Wang JJ, Li S - "Effect of selenium on main cytochrome P450 isoenzymes in liver of fluorotic chicks" Journal of Animal Husbandry and Veterinary Medicine 40(6):922-927 (2009)
Xia T, Wang A, Yu R, Tan L, Chen J, Chen X – "Experimental study on antagonistic effects of Se-Zn agent on chronic fluorosis" Chinese Journal of Endemiology 20(3):180-182 (2001) PFPC Library
Xiu Ruiqin, Gao Shirong, Xu Yongxiang, et al. - "Study on joint toxicity of fluoride and selenium to fish" China Environmental Science 15(5):348-350 (1995)The Se-Zn preparation increased urinary fluoride excretion and enhanced antioxidant defenses, as shown by higher whole-blood GSH-Px activity, higher renal SOD activity, and increased renal GSH content, compared with the fluoride-only group. At the same time, urinary γ-GT activity and renal LPO levels were reduced.
Conclusion: Within the tested dose range, the Se-Zn preparation markedly antagonized chronic fluorosis, probably by promoting fluoride excretion and inhibiting fluoride-induced lipid peroxidation through enhancement of antioxidant enzyme activity and GSH levels
https://europepmc.org/article/cba/285541
Zhang Z, Shen X, Xu X – "Effect of selenium on fluoride induced impairment of learning and memory in mice" Journal of Hygiene Research 30(3):144-146 (2001)Abstract
The joint toxicity of fluoride and selenium to zebrafish (B. rerio) was evaluated in both acute and long-term exposure tests. The additive index method was used to assess combined toxic effects. In acute tests with a fluoride:selenium concentration ratio of 1:1, the combined toxicity was antagonistic at 24 h, 48 h, and 96 h in one series of tests. In another series of acute tests at the same 1:1 ratio, the interaction was antagonistic at 24 h, additive at 48 h, and synergistic at 96 h. In the long-term exposure tests, the combined toxicity to zebrafish showed a synergistic effect.
Zhang R, Liao QX, Ke LL, Ouyang W, Zhang ZG – "The molecular mechanisms of the renal injury in fluorosis induced by drinking water with a high fluoride ion content and the effects of selenium intervention" Fluoride 50(1 Pt 2):105-120 (2017)
Zheng X, Sun Y, Ke L, Ouyang W, Zhang Z - "Molecular mechanism of brain impairment caused by drinking-acquired fluorosis and selenium intervention" Environ Toxicol Pharmacol 43:134-139 (2016)
- Fluoride deficiency as a cause of Kashin Beck disease
- Yang S - "An investigation, analysis, and observation of the coexistence of Kashin-Beck disease and fluorosis" Chinese Community Physician (11):6-6 (2004) PFPC Library
- see: Li D - "An explanation of the low fluoride theory in Kashin-Beck disease" Jilin Geology (4):100-104 (2007) (2004) PFPC Library
This paper proposes a new etiological theory for Kashin-Beck disease (KBD), namely that low environmental fluoride is the primary cause. Drawing on modern theories from geoscience, chemistry and medicine, the author conducts a detailed and systematic investigation of factors affecting the skeletal system in endemic areas, including elements that “nourish” bone, and explores both the pathogenesis of KBD and effective preventive and therapeutic measures for daily life.
The study suggests that low fluoride levels in the geological environment and in drinking water are the fundamental causes of KBD. Where there are no alternative fluoride sources, a fluoride concentration in drinking water below 0.2 mg/L is associated with mild KBD, while levels below 0.1 mg/L are associated with severe KBD. Because of this low-fluoride exposure, metabolic disorders may occur in the human body, with inadequate synthesis of bone matrix and inorganic bone salts, leading to undernourished bone, particularly in the long bones. Based on these findings, the paper proposes specific measures for fluoride supplementation in humans as a means to prevent and treat Kashin-Beck disease.
- He J, Yong H, Jia X, Wu X, Li S - "Study on relationship between selenium and fluoride concentrations in drinking water and Kaschin-Beck disease in Aba Prefecture" Groundwater (2):9-10 (2012) PFPC Library
The average selenium and fluoride concentrations in drinking water in Aba Prefecture ranged from 0.47 to 2.32 µg/L and from 0.08 to 0.38 mg/L, respectively. Selenium and fluoride levels in drinking water were significantly different between endemic and non-endemic areas (t = 2.12 and 3.26, respectively, p < 0.01). In endemic areas, selenium and fluoride concentrations in drinking water showed a significant negative correlation with the prevalence of KBD.
Conclusion
Selenium and fluoride concentrations in drinking water in Aba Prefecture are closely associated with KBD. For KBD prevention and control, in addition to necessary selenium supplementation, it is also necessary to increase the fluoride content in drinking water to meet the requirements for normal bone growth.
Selenium & Iodine
Arthur JR, Beckett GJ, Mitchell JH - "The interactions between selenium and iodine deficiencies in man and animals" Nutr Res Rev 12(1):55-73 (1999)
https://doi.org/10.1079/095442299108728910
Aydin K, Kendirci M, Kurtoğlu S, Karaküçük EI, Kiriş A - "Iodine and selenium deficiency in school-children in an endemic goiter area in Turkey" J Pediatr Endocrinol Metab 15(7):1027-1031 (2002)
https://pubmed.ncbi.nlm.nih.gov/12199330/
Bellisola G, Brätter P, Cinque G, et al - "The TSH-dependent variation of the essential elements iodine, selenium, and zinc within human thyroid tissue" J Trace Elem Med Biol 12:177-182 (1998)
https://doi.org/10.1016/S0946-672X(98)80006-0
Campos RO, de Jesus LM, Morais DA, Júnior WTdS, Souza VCdO, Oliveira CA, Júnior FB, Macedo M, Ramos HE - "Low urinary selenium levels are associated with iodine deficiency in Brazilian schoolchildren and adolescents" Endocrine 73(3):609-616 (2021)
Contempré B, Duale NL, Dumont JE, Ngo B, Diplock AT, Vanderpas J - "Effect of selenium supplementation on thyroid hormone metabolism in an iodine and selenium deficient population" Clin Endocrinol (Oxf) 36(6):579-583 (1992)
https://doi.org/10.1111/j.1365-2265.1992.tb02268.x
Erdoğan MF, Erdoğan G, Sav H, Güllü S, Kamel N - "Endemic goiter, thiocyanate overload, and selenium status in school-age children" Biol Trace Elem Res 79(2):121-130 (2001)
https://doi.org/10.1385/BTER:79:2:121
Gashu D, Marquis GS, Bougma K, Stoecker BJ - "Selenium inadequacy hampers thyroid response of young children after iodine repletion" J Trace Elem Med Biol 50:291-295 (2018)
Giray B, Hincal F, Teziç T, Okten A, Gedik Y - "Status of selenium and antioxidant enzymes of goitrous children is lower than healthy controls and nongoitrous children with high iodine deficiency" Biol Trace Elem Res 82(1-3):35-52 (2001)
https://doi.org/10.1385/BTER:82:1-3:035
Kryczyk-Kozioł J, Prochownik E, Dobrowolska-Iwanek J, Paśko P, Kleszcz K, Francik R, Potok H, Nieckula M, Cisoń-Apanasewicz U, Jabłońska P, Ogonowska D, Kuzera G, Krośniak M, Klobučar S, Zagrodzki P - "Iodine and selenium status in relation to thyroid and immune functions - the analysis of their dependencies in a group of women of reproductive age from the southern region of Poland" Nutrients 17(12):1952 (2025)
https://doi.org/10.3390/nu17121952
Lossow K, Renko K, Schwarz M, Schomburg L, Schwerdtle T, Kipp AP – "The Nutritional Supply of Iodine and Selenium Affects Thyroid Hormone Axis Related Endpoints in Mice" Nutrients 13(11):3773 (2021)
https://doi.org/10.3390/nu13113773
Mayunga KC, Kootstra-Ros JE, Oosterink JE, et al - "Pregnant Dutch women have inadequate iodine status and selenium intake" Nutrients 14(19):3936 (2022)Abstract
Selenium and iodine are the two central trace elements for the homeostasis of thyroid hormones but additional trace elements such as iron, zinc, and copper are also involved. To compare the primary effects of inadequate intake of selenium and iodine on the thyroid gland, as well as the target organs of thyroid hormones such as liver and kidney, mice were subjected to an eight-week dietary intervention with low versus adequate selenium and iodine supply. Analysis of trace element levels in serum, liver, and kidney demonstrated a successful intervention. Markers of the selenium status were unaffected by the iodine supply. The thyroid gland was able to maintain serum thyroxine levels even under selenium-deficient conditions, despite reduced selenoprotein expression in liver and kidney, including deiodinase type 1. Thyroid hormone target genes responded to the altered selenium and iodine supply, whereas the iron, zinc, and copper homeostasis remained unaffected. There was a notable interaction between thyroid hormones and copper, which requires further clarification. Overall, the effects of an altered selenium and iodine supply were pronounced in thyroid hormone target tissues, but not in the thyroid gland.
https://doi.org/10.3390/nu14193936
Mullan KR, McMullan P, Hunter A, McCance DR, Smyth P, Bath SC, Rayman M, Woodside JV - "Selenium status in a Northern Irish pregnant cohort with iodine deficiency" Eur J Clin Nutr 75(2):403-405 (2021)
https://doi.org/10.1038/s41430-020-00721-4
Murillo M, Carrión N, Quintana M, Sanabria G, Ríos M, Duarte L, Ablan F - "Determination of selenium and iodine in human thyroids" J Trace Elem Med Biol 19(1):23-27 (2005)
https://doi.org/10.1016/j.jtemb.2005.07.005
Ngo DB, Dikassa L, Okitolonda W, Gervy C, Dumont JE, Vanweydeveld P, Contempré B - "Selenium status in pregnant women of a rural population (Zaire) in relationship to iodine deficiency" Trop Med Int Health 2(6):572-581 (1997)
Rasmussen LB, Schomburg L, Köhrle J, Pedersen IB, Hollenbach B, Hög A, Ovesen L, Perrild H, Laurberg P - "Selenium status, thyroid volume, and multiple nodule formation in an area with mild iodine deficiency" Eur J Endocrinol 164(4):585-590 (2011)
https://doi.org/10.1530/EJE-10-1026
Stråvik M, Sandin A, Aksglaede L, Papadogiannakis N, Ahlsson F, Jacobson T, Kippler M - "Infant iodine and selenium status in relation to maternal status and diet during pregnancy and lactation" Front Nutr 8:733602 (2021)
https://doi.org/10.3389/fnut.2021.733602
Teng D, Yang W, Shi X, Li Y, Ba J, Chen B, Du J, He L, Lai X, Li Y, et al. – "An Inverse Relationship Between Iodine Intake and Thyroid Antibodies: A National Cross-Sectional Survey in Mainland China" Thyroid 30(11):1656-1665 (2020)
https://doi.org/10.1089/thy.2020.0037
Vanderpas JB, Contempré B, Duale NL, Goossens W, Bebe N, Thorpe R, Ntambue K, Dumont J, Thilly CH, Diplock AT - "Iodine and selenium deficiency associated with cretinism in northern Zaire" Am J Clin Nutr 52(6):1087-1093 (1990)
https://doi.org/10.1093/ajcn/52.6.1087
Vanderpas JB, Contempré B, Duale NL, Deckx H, Bebe N, Longombé AO, Thilly CH, Diplock AT, Dumont JE - "Selenium deficiency mitigates hypothyroxinemia in iodine-deficient subjects" Am J Clin Nutr 57(2 Suppl):271S-275S (1993)
https://doi.org/10.1093/ajcn/57.2.271S
Wang B, He W, Li Q, Jia X, Yao Q, Song R, Qin Q, Zhang JA – "U-shaped relationship between iodine status and thyroid autoimmunity risk in adults" Eur J Endocrinol 181(3):255-266 (2019)
https://doi.org/10.1530/EJE-19-0212
Yang XF, Hou XH, Xu J, Guo HL, Yinq CJ, Chen XY, Sun XF - "Effect of selenium supplementation on activity and mRNA expression of type 1 deiodinase in mice with excessive iodine intake" Biomed Environ Sci 19(4):302-8 (2006)
https://pubmed.ncbi.nlm.nih.gov/17044649/
Zagrodzki P, Szmigiel H, Ratajczak R, Szybinski Z, Zachwieja Z - "The role of selenium in iodine metabolism in children with goiter" Environ Health Perspect 108(1):67-71 (2000)
https://doi.org/10.1289/ehp.0010867
Zhang C, Wang H, Teng W, Shan Z - "The relationships among the urinary iodine concentration, selenium intake, and thyroid antibodies in adults, including the interaction between iodine and selenium: National Health and Nutrition Examination Survey 2007-2012" Nutrients 16(20):3443 (2024)
https://doi.org/10.3390/nu16203443
Selenium - head circumference - trimester 3
Chen D, Wang J, Zhou H, Dong M, Liu X, Ma W, Zhang B, Liu T, Zeng Z – "Associations between selenium exposure level during pregnancy and fetal head circumference in third trimester of pregnancy" Journal of Environmental and Occupational Medicine 38(4):361-367 (2021)
https://doi.org/10.13213/j.cnki.jeom.2021.20431
Among the 2 739 pregnant women, there were 1 926 pregnant women aged ≥ 30 years (70.3%), 1 474 male fetuses (53.8%), 2 313 pregnant women with high school education and above (84.4%), 871 pregnant women exposed to passive smoke during pregnancy (31.8%), and 2 637 pregnant women with gestational age ≥ 37 weeks (95.6%). The median (P25, P75) of urinary Se level was 38.5 (30.1, 44.5) μg·g⁻¹ in the first trimester and 38.9 (28.7, 54.0) μg·g⁻¹ in the thrid trimester, respectively. The head circumference of fetuses in the third trimester was (218.1 ± 41.4) mm. According to the results of multiple linear regression models, no association was found between the Se level in the first trimester and the fetal head circumference in the third trimester. For each unit increase of urinary lnωSe in the third trimester, the decrease in fetal head circumference and its 95% confidence interval (CI) were 7.04 (3.41–10.67) mm (P < 0.001). The participants were divided into four groups (Q1–Q4) according to the quartiles of lnωSe in the third trimester. Compared with the Q1 group, the head circumference of fetuses in the Q4 group decreased by 19.47 (12.50–26.43) mm (P < 0.001). In the third trimester of pregnancy, for each unit increase in lnωSe, the head circumference of male and female fetuses decreased by 5.06 (0.48–9.63) mm (P = 0.031) and 11.30 (5.32–17.27) mm (P < 0.001) respectively, and the difference between male and female fetuses was 6.24 (1.69–10.79) mm; compared with the Q1 group, the head circumference of male and female fetuses in the Q4 group was reduced by 18.13 (8.45–27.81) mm (P < 0.001) and 21.26 (11.23–31.30) mm (P < 0.001) respectively.
[Conclusion] Under the exposure level of the selected population, a higher urinary Se level in the third trimester is associated to a reduction of fetal head circumference in the third trimester.
Selenium & Hashimoto's
Toraih EA, Yaghi S, Ardis C, Tran L, Abdelmaksoud A, Elshazli RM, Hussein MH, Patel H, Elmorsy EM, Jishu JA, Aiash H, Fawzy MS - "Clinical outcomes of selenium supplementation in Hashimoto's thyroiditis without selenium deficiency: A large-scale retrospective cohort study" Endocrinol Diabetes Metab 9(3):e70239 (2026)
https://doi.org/10.1002/edm2.70239
"Selenium supplementation in Hashimoto's thyroiditis was associated with worsened biochemical autoimmunity, increased autoimmune comorbidity and higher symptomatic treatment burden."