Last Updated: October 3, 2022

Iron is an essential mineral best known for allowing blood to carry oxygen between tissues. Except in case of deficiency, iron supplementation has no proven benefit; on the contrary, it can lead to iron poisoning.

Iron is most often used for


What is iron?

Iron is an essential dietary mineral present in a wide variety of foods. In its main role in the body, iron is a critical component of hemoglobin — the oxygen carrier of red blood cells — and a deficiency in iron leads to poor oxygen transport (anemia). In addition, iron acts as a cofactor for many enzymes. The iron found in plants (notably grains and legumes) is less bioavailable than the iron found in meat (in the form of heme). Iron is the double-edged sword of the nutrient world. On the one hand, many people have insufficient levels, but on the other hand, iron overload can be toxic to a wide variety of cells. Iron deficiency is the only reason to consider iron supplementation, though getting more iron through foods is preferable when possible. For people who already have enough iron, taking an iron supplement has no proven benefit, and on the contrary, it can lead to iron overdose.

What are the benefits of iron?

A lack of iron tends to produce fatigue, depression, impaired cognitive function, restless leg syndrome, and other adverse effects. Correction of an iron deficiency tends to improve symptoms, and even among people who aren't anemic, more than the bare minimum amount of iron may be needed to produce the optimal amounts of hemoglobin and reap the benefits of greater oxygen delivery; however, the beneficial effect is probably limited to people whose iron levels are low according to conventional standards, though more research is needed. Iron supplements are also often used by athletes in an attempt to improve physical performance, however once again there does not appear to be any benefit when iron levels are not low. Iron deficiency is fairly common, and a great number of factors negatively affect iron status, so iron supplementation and iron-rich diets can be expected to benefit many people.

What are the downsides of iron?

Supplementation can produce nausea, headaches, and other symptoms. As previously mentioned, iron overload is a serious health risk.

Dosage information

Make sure that you get the recommended daily allowance (RDA) for your gender, age, and situation:

  • 8 mg for men and nonmenstruating women
  • 15 mg for menstruating women 14–18 years old
  • 18 mg for menstruating women 19–50 years old
  • 27 mg for pregnant women
  • 10 mg for lactating women less than 18 years old
  • 9 mg for lactating women, 19–50 years old

Those numbers include the iron in your diet. Getting enough iron from foods makes supplementation unnecessary. Be careful not to ingest more iron than the daily tolerable upper intake level (UL) for your age, e.g., 45 mg for people older than 13.

For more details, see the Recommended Intake section below.

Examine Database: Iron
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  1. ^McLean E, Cogswell M, Egli I, Wojdyla D, de Benoist BWorldwide prevalence of anaemia, WHO Vitamin and Mineral Nutrition Information System, 1993-2005Public Health Nutr.(2009 Apr)
  2. ^Clark SFIron deficiency anemiaNutr Clin Pract.(2008 Apr-May)
  3. ^Emerit J, Beaumont C, Trivin FIron metabolism, free radicals, and oxidative injuryBiomed Pharmacother.(2001 Jul)
  4. ^McCord JMIron, free radicals, and oxidative injurySemin Hematol.(1998 Jan)
  5. ^Kell DBTowards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examplesArch Toxicol.(2010 Nov)
  6. ^Fang X, An P, Wang H, Wang X, Shen X, Li X, Min J, Liu S, Wang FDietary intake of heme iron and risk of cardiovascular disease: a dose-response meta-analysis of prospective cohort studiesNutr Metab Cardiovasc Dis.(2015 Jan)
  7. ^Qiao L, Feng YIntakes of heme iron and zinc and colorectal cancer incidence: a meta-analysis of prospective studiesCancer Causes Control.(2013 Jun)
  8. ^Morris CCPediatric iron poisonings in the United StatesSouth Med J.(2000 Apr)
  9. ^Dean BS, Krenzelok EPMultiple vitamins and vitamins with iron: accidental poisoning in childrenVet Hum Toxicol.(1988 Feb)
  10. ^Brune M, Rossander L, Hallberg LIron absorption and phenolic compounds: importance of different phenolic structuresEur J Clin Nutr.(1989 Aug)
  11. ^Skikne B, Lynch S, Borek D, Cook JIron and blood donationClin Haematol.(1984 Feb)
  12. ^Sim Y Ong, Lyle C Gurrin, Lara Dolling, Jeanette Dixon, Amanda J Nicoll, Michelle Wolthuizen, Erica M Wood, Gregory J Anderson, Grant A Ramm, Katrina J Allen, John K Olynyk, Darrell Crawford, Louise E Ramm, Paul Gow, Simon Durrant, Lawrie W Powell, Martin B DelatyckiReduction of Body Iron in HFE-related Haemochromatosis and Moderate Iron Overload (Mi-Iron): A Multicentre, Participant-Blinded, Randomised Controlled TrialLancet Haematol.(2017 Dec)
  13. ^Fabrice Lainé, Marc Ruivard, Véronique Loustaud-Ratti, Fabrice Bonnet, Paul Calès, Edouard Bardou-Jacquet, Sylvie Sacher-Huvelin, Xavier Causse, Christine Beusnel, Alain Renault, Eric Bellissant, Yves Deugnier, Study GroupMetabolic and Hepatic Effects of Bloodletting in Dysmetabolic Iron Overload Syndrome: A Randomized Controlled Study in 274 PatientsHepatology.(2017 Feb)
  14. ^Elahe Mohammadi, Ahmad Tamaddoni, Durdi Qujeq, Esmat Nasseri, Farid Zayeri, Hamid Zand, Mahdi Gholami, Seyed Mostafa MirAn Investigation of the Effects of Curcumin on Iron Overload, Hepcidin Level, and Liver Function in β-Thalassemia Major Patients: A Double-Blind Randomized Controlled Clinical TrialPhytother Res.(2018 Sep)
  15. ^Brittin HC, Nossaman CEIron content of food cooked in iron utensilsJ Am Diet Assoc.(1986 Jul)
  16. ^Geerligs PD, Brabin BJ, Omari AAFood prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries: a systematic reviewJ Hum Nutr Diet.(2003 Aug)
  17. ^Adish AA, Esrey SA, Gyorkos TW, Jean-Baptiste J, Rojhani AEffect of consumption of food cooked in iron pots on iron status and growth of young children: a randomised trialLancet.(1999 Feb 27)
  18. ^Thyssen JP, Menné TMetal allergy--a review on exposures, penetration, genetics, prevalence, and clinical implicationsChem Res Toxicol.(2010 Feb 15)
  19. ^Kuligowski J, Halperin KMStainless steel cookware as a significant source of nickel, chromium, and ironArch Environ Contam Toxicol.(1992 Aug)
  20. ^Chiang TA, Wu PF, Ko YCIdentification of carcinogens in cooking oil fumesEnviron Res.(1999 Jul)
  21. ^Skog K, Viklund G, Olsson K, Sjöholm IAcrylamide in home-prepared roasted potatoesMol Nutr Food Res.(2008 Mar)
  22. ^Sugimura T, Wakabayashi K, Nakagama H, Nagao MHeterocyclic amines: Mutagens/carcinogens produced during cooking of meat and fishCancer Sci.(2004 Apr)
  23. ^Konings EJ, Ashby P, Hamlet CG, Thompson GAAcrylamide in cereal and cereal products: a review on progress in level reductionFood Addit Contam.(2007)
  24. ^Woodhall S, Stamford MPTFE toxicity in birdsVet Rec.(2004 Dec 11)
  25. ^Hamaya R, Ono Y, Chida Y, Inokuchi R, Kikuchi K, Tameda T, Tase C, Shinohara KPolytetrafluoroethylene fume-induced pulmonary edema: a case report and review of the literatureJ Med Case Rep.(2015 May 14)
Examine Database References
  1. Depression Symptoms - McClung JP, Karl JP, Cable SJ, Williams KW, Nindl BC, Young AJ, Lieberman HRRandomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and moodAm J Clin Nutr.(2009 Jul)
  2. Aerobic Exercise Metrics - Waldvogel S, Pedrazzini B, Vaucher P, Bize R, Cornuz J, Tissot JD, Favrat BClinical evaluation of iron treatment efficiency among non-anemic but iron-deficient female blood donors: a randomized controlled trialBMC Med.(2012 Jan 24)
  3. Fatigue (non-anemic) - Favrat B, Balck K, Breymann C, Hedenus M, Keller T, Mezzacasa A, Gasche CEvaluation of a single dose of ferric carboxymaltose in fatigued, iron-deficient women--PREFER a randomized, placebo-controlled studyPLoS One.(2014 Apr 21)
  4. Heart Rate - Brownlie T 4th, Utermohlen V, Hinton PS, Giordano C, Haas JDMarginal iron deficiency without anemia impairs aerobic adaptation among previously untrained womenAm J Clin Nutr.(2002 Apr)
  5. Muscular Endurance - Brutsaert TD, Hernandez-Cordero S, Rivera J, Viola T, Hughes G, Haas JDIron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic womenAm J Clin Nutr.(2003 Feb)
  6. Anxiety Symptoms - Vaucher P, Druais PL, Waldvogel S, Favrat BEffect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trialCMAJ.(2012 Aug 7)
  7. Fatigue (non-anemic) - Verdon F, Burnand B, Stubi CL, Bonard C, Graff M, Michaud A, Bischoff T, de Vevey M, Studer JP, Herzig L, Chapuis C, Tissot J, Pécoud A, Favrat BIron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trialBMJ.(2003 May 24)
  8. Fatigue (non-anemic) - Krayenbuehl PA, Battegay E, Breymann C, Furrer J, Schulthess GIntravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentrationBlood.(2011 Sep 22)
  9. Aerobic Exercise Metrics - Woods A, Garvican-Lewis LA, Saunders PU, Lovell G, Hughes D, Fazakerley R, Anderson B, Gore CJ, Thompson KGFour weeks of IV iron supplementation reduces perceived fatigue and mood disturbance in distance runnersPLoS One.(2014 Sep 23)
  10. Fibromyalgia Symptoms - Chad S Boomershine, Todd A Koch, David MorrisA Blinded, Randomized, Placebo-Controlled Study to Investigate the Efficacy and Safety of Ferric Carboxymaltose in Iron-Deficient Patients with FibromyalgiaRheumatol Ther.(2018 Jun)