In regions with severe iodine deficiency, iodine fortification (mainly through iodisation of salt) decreases the prevalence of hypothyroidism.[1]Chaker L, Razvi S, Bensenor IM, et al. Hypothyroidism. Nat Rev Dis Primers. 2022 May 19;8(1):30.
http://www.ncbi.nlm.nih.gov/pubmed/35589725?tool=bestpractice.com
In regions with sufficient iodine intake, avoidance of iodine excess protects against the development of autoimmune thyroiditis, the most common cause of primary hypothyroidism.[27]Rayman MP. Multiple nutritional factors and thyroid disease, with particular reference to autoimmune thyroid disease. Proc Nutr Soc. 2019 Feb;78(1):34-44.
https://www.doi.org/10.1017/S0029665118001192
http://www.ncbi.nlm.nih.gov/pubmed/30208979?tool=bestpractice.com
[28]Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2014 Mar;10(3):136-42.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976240
http://www.ncbi.nlm.nih.gov/pubmed/24342882?tool=bestpractice.com
It is unclear whether routine iodine supplementation is beneficial for pregnant women.[48]Harding KB, Peña-Rosas JP, Webster AC, et al. Iodine supplementation for women during the preconception, pregnancy and postpartum period. Cochrane Database Syst Rev. 2017 Mar 5;3(3):CD011761.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6464647
http://www.ncbi.nlm.nih.gov/pubmed/28260263?tool=bestpractice.com
The World Health Organization recommends iodine supplementation for pregnant and lactating women in countries where <20% of households have access to iodised salt.[49]World Health Organization. e-Library of evidence for nutrition actions (eLENA): iodine supplementation in pregnant and lactating women. Aug 2023 [internet publication].
https://www.who.int/tools/elena/interventions/iodine-pregnancy
In many other countries women commonly take multiple‐micronutrient supplements, often containing iodine, during pregnancy.