编辑“︁碘”︁（章节）

== 對人體的影響 ==
{{medical}}
{{main|{{le|生物学中的碘|Iodine in biology}}}}
[[File:Thyroid system.svg|thumb|upright=1.2|甲状腺激素[[三碘甲腺原氨酸|T<sub>3</sub>]]和[[四碘甲腺原氨酸|T<sub>4</sub>]]在体内的运作系统]]
碘是人體必需的[[礦物質]]，用以製造甲状腺激素[[四碘甲腺原氨酸]]和[[三碘甲腺原氨酸]]（缩写分别为T<sub>4</sub>和T<sub>3</sub>，以碘原子的数量命名）是以調控細胞代謝、神經性肌肉組織發展與成長（特別是在出生胎兒的腦部）<ref>{{cite book | last=Gropper | first=Sareen Annora Stepnick | last2=Smith | first2=Jack L. | last3=Groff | first3=James L. | title=Advanced nutrition and human metabolism | publisher=Thomson/Wadsworth | publication-place=Belmont, CA | date=2004 | isbn=0-534-55986-7 | oclc=55135458|page=468-473}}</ref>。缺碘会使T<sub>3</sub>和T<sub>4</sub>的合成量减少，且使[[甲状腺]]为了得到碘而变大，造成[[甲状腺肿]]。血液中的甲状腺激素主要由生物半衰期较长的四碘甲腺原氨酸（T<sub>4</sub>）组成，人血中T<sub>4</sub>和T<sub>3</sub>的比例在14:1到20:1之间。T<sub>4</sub>会通过{{le|脱碘酶|deiodinase}}转化成生物活性更高的T<sub>3</sub>，而T<sub>3</sub>会进一步[[脱羧]]和脱碘，生成{{le|3-碘甲状腺原胺|iodothyronamine}}（T<sub>1</sub>a）和{{le|甲状腺原胺|thyronamine}}（T<sub>0</sub>a'）。脱碘酶含有[[硒]]，因此人体合成T<sub>3</sub>需要硒。<ref>{{cite web|url=http://emedicine.medscape.com/article/819692-overview#showall|vauthors=Irizarry L|title=Thyroid Hormone Toxicity|website=Medscape|publisher=WedMD LLC|date=23 April 2014|access-date=2 May 2014|archive-date=2021-10-31|archive-url=https://web.archive.org/web/20211031132146/https://emedicine.medscape.com/article/819692-overview#showall|dead-url=no}}</ref>

碘占了T<sub>4</sub>分子量的65%，以及T<sub>3</sub>分子量的59%。有15–20&nbsp;mg的碘储存在甲状腺中，而70%的碘存在于其它组织中，包括乳腺、眼睛、胃粘膜、胎儿胸腺、脑脊髓液和脉络丛、动脉壁、宫颈和唾液腺。在这些组织中，碘化物会通过{{le|钠碘同向运输蛋白|sodium-iodide symporter}}（NIS）直接进入细胞。乳腺组织中的碘与胎儿和新生儿发育有关，但碘在其它组织的作用仍有不明确的地方。<ref name="Patrick2008" />

=== 膳食摄取量 ===
[[美国国家医学院]]推荐的碘摄入量为一岁以下婴儿110~130 [[微克|µg]]，1~8岁儿童90&nbsp;µg，9~13岁儿童120&nbsp;µg，成年人150&nbsp;µg，孕妇220&nbsp;µg，哺乳期妇女290&nbsp;µg。<ref name="lpi" /><ref>{{cite web|url=http://iom.edu/en/Global/News%20Announcements/~/media/Files/Activity%20Files/Nutrition/DRIs/DRISummaryListing2.ashx |archive-url=https://web.archive.org/web/20091030004039/http://iom.edu/en/Global/News%20Announcements/~/media/Files/Activity%20Files/Nutrition/DRIs/DRISummaryListing2.ashx |url-status=dead |archive-date=30 October 2009 |title=Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals, Vitamins |publisher=[[Institute of Medicine]] |date=2004 |access-date=9 June 2010 }}</ref>成年人对碘的可耐受最高摄入量（UL）为每天1,100&nbsp;μg<ref name="InstituteofMedicine">{{Cite book| author = United States National Research Council| date = 2000| title = Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc| pages = 258–259| publisher = National Academies Press| url = http://books.nap.edu/openbook.php?record_id=10026&page=258| doi = 10.17226/10026| pmid = 25057538| isbn = 978-0-309-07279-3| access-date = 2022-12-02| archive-date = 2015-07-25| archive-url = https://web.archive.org/web/20150725203752/http://books.nap.edu/openbook.php?record_id=10026&page=258| dead-url = no}}</ref>，此上限是通过分析补充剂对[[促甲状腺激素]]的影响而定的。<ref name="Patrick2008" />

甲状腺合成一天的T<sub>4</sub>和T<sub>3</sub>不需要超过70&nbsp;μg的碘。<ref name="lpi" />超过这个值的推荐碘摄入量用来使许多身体系统，包括[[胃黏膜]]、[[唾液腺]]、脑细胞、[[脉络丛]]、[[胸腺]]和[[动脉]]壁保持最佳状态。<ref name="lpi" /><ref>{{cite journal | vauthors = Venturi S, Venturi M | title = Iodine, thymus, and immunity | journal = Nutrition | volume = 25 | issue = 9 | pages = 977–979 | date = September 2009 | pmid = 19647627 | doi = 10.1016/j.nut.2009.06.002 }}</ref><ref>{{cite journal | vauthors = Ullberg S, Ewaldsson B | title = Distribution of radio-iodine studied by whole-body autoradiography | url = https://archive.org/details/sim_acta-radiologica_1964-02_2_1/page/24 | journal = Acta Radiologica | volume = 2 | pages = 24–32 | date = February 1964 | pmid = 14153759 | doi = 10.3109/02841866409134127 }}</ref><ref name="Venturi, Sebastiano 2014 185–205">{{Cite journal| vauthors = Venturi S |title=Iodine, PUFAs and Iodolipids in Health and Disease: An Evolutionary Perspective|journal=Human Evolution|volume= 29 |issue= 1–3|pages=185–205|year=2014|issn=0393-9375}}</ref>

碘的天然食物来源包括[[海产]]（如鱼、[[海带]]和[[贝类]]）、乳制品和[[蛋]]。<ref>{{cite web| publisher =Iodine Global Network|url =http://ign.org/p142002146.html|archive-url=https://web.archive.org/web/20150813130042/http://ign.org/p142002146.html|archive-date=13 August 2015|title=Where do we get iodine from?|url-status=live}}</ref><ref name = medlineplus002421/>[[含碘食盐]]中加入了[[碘化钠]]来增加碘含量。<ref name="medlineplus002421">{{cite encyclopedia| url = https://www.nlm.nih.gov/medlineplus/ency/article/002421.htm| title = Iodine in diet| encyclopedia = MedlinePlus Medical Encyclopedia| access-date = 2022-12-02| archive-date = 2016-07-05| archive-url = https://web.archive.org/web/20160705122918/https://www.nlm.nih.gov/medlineplus/ency/article/002421.htm| dead-url = no}}</ref><ref name="American Thyroid Association">{{cite web|title=American Thyroid Association|url=http://www.thyroid.org/iodine-deficiency/|work=thyroid.org|publisher=American Thyroid Association|access-date=4 April 2014|archive-date=2023-08-03|archive-url=https://web.archive.org/web/20230803045045/https://www.thyroid.org/iodine-deficiency/|dead-url=no}}</ref>

2000年，美国男人和女人的碘摄入量中位数分别为每天240–300&nbsp;μg和190–210&nbsp;μg。<ref name="InstituteofMedicine" />美国人的碘摄入量足够，<ref>{{cite journal | vauthors = Caldwell KL, Makhmudov A, Ely E, Jones RL, Wang RY | title = Iodine status of the U.S. population, National Health and Nutrition Examination Survey, 2005–2006 and 2007–2008 | journal = Thyroid | volume = 21 | issue = 4 | pages = 419–427 | date = April 2011 | pmid = 21323596 | doi = 10.1089/thy.2010.0077 | url = https://zenodo.org/record/1235283 | access-date = 2022-12-02 | archive-date = 2022-12-02 | archive-url = https://web.archive.org/web/20221202135223/https://zenodo.org/record/1235283 | dead-url = no }}</ref><ref name="Lueng">{{cite journal | vauthors = Leung AM, Braverman LE, Pearce EN | title = History of U.S. iodine fortification and supplementation | journal = Nutrients | volume = 4 | issue = 11 | pages = 1740–1746 | date = November 2012 | pmid = 23201844 | pmc = 3509517 | doi = 10.3390/nu4111740 | doi-access = free }}</ref>而育龄妇女和孕妇可能有轻微的碘缺乏症风险。<ref name="Lueng" />有认为日本人源自{{le|昆布|Kombu}}<ref name="Patrick2008">{{cite journal | vauthors = Patrick L | title = Iodine: deficiency and therapeutic considerations | journal = Alternative Medicine Review | volume = 13 | issue = 2 | pages = 116–127 | date = June 2008 | pmid = 18590348 | url = http://www.thorne.com/altmedrev/.fulltext/13/2/116.pdf | url-status = dead | archive-url = https://web.archive.org/web/20130531112100/http://www.thorne.com/altmedrev/.fulltext/13/2/116.pdf | archive-date = 31 May 2013 }}</ref>的碘摄入量很高，达到每天5,280–13,800&nbsp;μg，但最新研究表明日本人的实际碘摄入量更接近于每天1,000–3,000&nbsp;μg。<ref>{{cite journal | vauthors = Zava TT, Zava DT | title = Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis | journal = Thyroid Research | volume = 4 | pages = 14 | date = October 2011 | pmid = 21975053 | pmc = 3204293 | doi = 10.1186/1756-6614-4-14 }}</ref>日本成年人的可耐受最高摄入量在2015年最后修改成了每天3,000&nbsp;µg。<ref>{{cite web |title=Overview of Dietary Reference Intakes for Japanese (2015) |publisher=Minister of Health, Labour and Welfare, Japan |url=http://www.mhlw.go.jp/file/06-Seisakujouhou-10900000-Kenkoukyoku/Overview.pdf |access-date=14 March 2022 |archive-date=2021-04-23 |archive-url=https://web.archive.org/web/20210423083531/https://www.mhlw.go.jp/file/06-Seisakujouhou-10900000-Kenkoukyoku/Overview.pdf |dead-url=no }}</ref>在食盐加碘等碘营养强化计划执行后发生一些由碘引起的[[甲亢]]病例（{{le|Jod-Basedow现象|Jod-Basedow phenomenon}}）。这种情况似乎主要发生在40岁以上的人群中，当碘缺乏症严重且碘摄入量突然剧增时，风险似乎更高。<ref>{{cite journal | vauthors = Wu T, Liu GJ, Li P, Clar C | title = Iodised salt for preventing iodine deficiency disorders | journal = The Cochrane Database of Systematic Reviews | volume = 2010 | issue = 3 | pages = CD003204 | date = 2002 | pmid = 12137681 | pmc = 9006116 | doi = 10.1002/14651858.CD003204 | veditors = Wu T }}</ref>

=== 缺乏 ===
{{main|碘缺乏症}}
当一个人的尿碘低于100μg/L时，他就患上了碘缺乏症。<ref>{{cite book | last=De Benoist | first=Bruno | author2=World Health Organization. Nutrition for Health and Development | title=Iodine status worldwide : WHO global database on iodine deficiency | publisher=Dept. of Nutrition for Health and Development, World Health Organization | publication-place=Geneva | date=2004 | isbn=978-92-4-159200-0 | oclc=58790071}}</ref>在饮食中碘含量较少的地区（如没有海产的偏远内陆地区和半干旱气候地区）生活的人较易得碘缺乏症。<ref name="Dissanayake">{{Cite journal| vauthors = Dissanayake CB, Chandrajith R, Tobschall HJ |title = The iodine cycle in the tropical environment – implications on iodine deficiency disorders|journal = International Journal of Environmental Studies|volume = 56 |page= 357| doi = 10.1080/00207239908711210|date = 1999|issue = 3}}</ref>[[碘缺乏症]]会导致[[甲状腺机能低下症]]，它的症状为极度疲劳、[[甲状腺肿]]、智力减退、抑郁、体重增加和基础体温下降。<ref>{{Cite book|chapter = Endemic Goiter|title = Endocrinology & metabolism|vauthors = Felig P, Frohman LA|publisher = McGraw-Hill Professional|date = 2001|isbn = 978-0-07-022001-0|chapter-url = https://books.google.com/books?id=AZUUGrp6yUgC&pg=RA1-PA351|access-date = 2022-12-02|archive-date = 2023-01-12|archive-url = https://web.archive.org/web/20230112212836/https://books.google.com/books?id=AZUUGrp6yUgC&pg=RA1-PA351|dead-url = no}}</ref>婴儿和小孩因缺碘而导致甲状腺功能减退造成的碘缺乏症是可避免的[[智能障碍]]的主因。发达国家采用食盐加碘的方法解决了该问题，但碘缺乏症在发展中国家里仍是严重的公共卫生问题。<ref>{{cite web|url =https://www.who.int/nutrition/topics/idd/en/|archive-url =https://web.archive.org/web/20060930020824/http://www.who.int/nutrition/topics/idd/en/|url-status =dead|archive-date =30 September 2006|title = Micronutrient deficiency: iodine deficiency disorders|publisher = WHO}}</ref>给中度缺碘儿童补充碘可改善他们的信息处理、精细动作技能和视觉问题解决能力。<ref>{{cite journal | vauthors = Zimmermann MB, Connolly K, Bozo M, Bridson J, Rohner F, Grimci L | title = Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study | url = https://archive.org/details/sim_american-journal-of-clinical-nutrition_2006-01_83_1/page/108 | journal = The American Journal of Clinical Nutrition | volume = 83 | issue = 1 | pages = 108–114 | date = January 2006 | pmid = 16400058 | doi = 10.1093/ajcn/83.1.108 | doi-access = free }}</ref>