Editing Iron deficiency (section)

==Causes==
Iron deficiency can be caused by many factors and health conditions and in many cases it can be treated with iron supplements.<ref name=":3" /> In women, blood loss from heavy periods is a common cause of iron deficiency.<ref name=":3" /> Pregnant women are at risk of iron deficiency.<ref name=":3" /> Internal bleeding such as from an ulcer in the stomach or intestines is another common cause.<ref name=":3" /> Blood loss from donating blood can contribute to iron deficiency.<ref name=":5" /> There are also other factors that put people at risk including:
* blood loss ([[hemoglobin]] contains iron)
** donation
** excessive [[menstrual bleeding]]
** non-menstrual [[bleeding]]
** bleeding from the [[gastrointestinal tract]] (anus) ([[Peptic ulcer|ulcers]], [[hemorrhoid]]s, [[ulcerative colitis]], [[stomach cancer|stomach]] or [[colon cancer]], etc.)
** rarely, [[laryngological]] bleeding or from the [[respiratory tract]]
** cancer
* Diet: inadequate iron intake {{crossreference|(see {{slink||Inadequate dietary intake}} below)}}
* substances (in diet or drugs) interfering with iron absorption
** Fluoroquinolone antibiotics<ref>{{cite journal | vauthors = Badal S, Her YF, Maher LJ | title = Nonantibiotic Effects of Fluoroquinolones in Mammalian Cells | journal = The Journal of Biological Chemistry | volume = 290 | issue = 36 | pages = 22287–97 | date = September 2015 | pmid = 26205818 | pmc = 4571980 | doi = 10.1074/jbc.M115.671222 | doi-access = free }}</ref>
* [[malabsorption]] syndromes
* [[inflammation]] where it is [[Evolutionary medicine|adaptive]] to limit bacterial growth in infection, but is also present in many other chronic diseases such as [[Inflammatory bowel disease]] and [[rheumatoid arthritis]]
* parasitic infection
Though [[genetic defects]] causing iron deficiency have been studied in rodents, there are no known genetic disorders of [[human iron metabolism]] that directly cause iron deficiency.{{Citation needed|date=January 2025}}

===Athletics===
Possible reasons that athletics may contribute to lower iron levels include mechanical [[hemolysis]] (destruction of red blood cells from physical impact), loss of iron through sweat and urine, gastrointestinal blood loss, and haematuria (presence of blood in urine).<ref name="Nielson">{{cite journal | vauthors = Nielsen P, Nachtigall D | title = Iron supplementation in athletes. Current recommendations | journal = Sports Medicine | volume = 26 | issue = 4 | pages = 207–16 | date = October 1998 | pmid = 9820921 | doi = 10.2165/00007256-199826040-00001 | s2cid = 25517866 }}{{dead link|date=December 2017|bot=medic}}{{cbignore|bot=medic}}</ref><ref name=Chatard>{{cite journal | vauthors = Chatard JC, Mujika I, Guy C, Lacour JR | title = Anaemia and iron deficiency in athletes. Practical recommendations for treatment | journal = Sports Medicine | volume = 27 | issue = 4 | pages = 229–40 | date = April 1999 | pmid = 10367333 | doi = 10.2165/00007256-199927040-00003 | series = 4 | s2cid = 32504228 }}</ref> Although small amounts of iron are excreted in sweat and urine, these losses can generally be seen as insignificant even with increased [[sweat]] and [[urine]] production, especially considering that athletes' bodies appear to become conditioned to retain iron better.<ref name="Nielson"/> [[Mechanical hemolytic anemia|Mechanical hemolysis]] is most likely to occur in high-impact sports, especially among long-distance runners who experience "foot-strike hemolysis" from the repeated impact of their feet with the ground. Exercise-induced [[gastrointestinal bleeding]] is most likely to occur in endurance athletes. [[March hemoglobinuria|Haematuria in athletes]] is most likely to occur in those that undergo repetitive impacts on the body, particularly affecting the feet (such as running on a hard road, or Kendo) and hands (e.g. [[Conga]] or [[Candombe]] drumming). Additionally, athletes in sports that emphasize weight loss (e.g. [[ballet]], [[gymnastics]], [[marathon running]], and [[cycle sport|cycling]]) as well as sports that emphasize high-[[carbohydrate]], low-[[fat]] diets, may be at an increased risk for iron deficiency.<ref name="Nielson"/><ref name="Chatard"/>

===Inadequate dietary intake===
A U.S. federal food consumption survey determined that for women and men over 19, average iron consumption from foods and beverages was 13.1 and 18.0&nbsp;mg/day, respectively. For women, 16% in the age range 14–50 years consumed less than the Estimated Average Requirement (EAR), and for men ages 19 and up, fewer than 3%.<ref>{{cite report | vauthors = Moshfegh A, Goldman J, Cleveland L | title = What we eat in America, NHANES 2001-2002: usual nutrient intakes from food compared to dietary reference intakes. | work = National Health and Nutrition Examination Survey (NHANES) | publisher = US Department of Agriculture, Agricultural Research Service | date = September 2005 | chapter-url = https://www.ars.usda.gov/SP2UserFiles/Place/80400530/pdf/0102/usualintaketables2001-02.pdf/ | archive-url = https://web.archive.org/web/20150106010550/https://www.ars.usda.gov/SP2UserFiles/Place/80400530/pdf/0102/usualintaketables2001-02.pdf | archive-date=6 January 2015 | chapter = Table A12: Iron}}</ref> Consumption data were updated in a 2014 U.S. government survey and reported that for men and women ages 20 and older the average iron intakes were, respectively, 16.6 and 12.6&nbsp;mg/day.<ref>{{cite web | url = https://www.ars.usda.gov/ARSUserFiles/80400530/pdf/1314/Table_1_NIN_GEN_13.pdf | title = What We Eat In America, NHANES 2013-2014 | work = National Health and Nutrition Examination Survey (NHANES) | publisher = US Department of Agriculture, Agricultural Research Service }}</ref> People in the U.S. usually obtain adequate amounts of iron from their diets.  However, subgroups like infants, young children, teenaged girls, pregnant women, and premenopausal women are at risk of obtaining less than the EAR.<ref name=NIHODS>{{Cite web |url=https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/ |title=Iron |work=Fact Sheet for Health Professionals |publisher=Office of Dietary Supplements. National Institutes of Health |date=February 2020 }}</ref> Socio-economic and racial differences further affect the rates of iron deficiency.<ref name=NIHODS/>