Iron is an essential mineral, which means that it is not produced by the body and it needs to be consumed on a regular basis to ensure optimal health. Iron has a variety of health benefits; what are those benefits, where is it found, and what are some signs of iron deficiency?
Where is iron found?
Iron is found in a variety of foods and fortified products, and it is found in the form of either nonheme or heme iron. Nonheme iron is found in plant-based foods, such as nuts, vegetables, iron-fortified cereals, and beans. Heme iron is found in animal products, such as seafood, liver, and some lean meats.1 Although both forms of iron get absorbed, heme iron may have a higher bioavailability than nonheme iron, which means that a greater percentage of what is consumed is absorbed by the body.1
Additionally, the absorption of iron may be altered by other dietary nutrients. Ascorbic acid, also known as vitamin C, may enhance the bioavailability of nonheme iron. On the other hand, calcium, polyphenols, and compounds in grains and beans called phytates may reduce the bioavailability of iron.2
Breast milk contains iron; however, the amount is not enough to fulfill the needs of infants over 6 months of age.1 Infant formula is usually fortified with iron sufficient to meet these needs.3
Iron is also available in dietary supplements, particularly iron supplements and multivitamin supplements containing iron. It is available in a variety of forms, including ferrous gluconate, ferrous sulfate, and ferrous fumarate.1 It is also available in heme polypeptides, which is a relatively new form of supplemental iron that has been reported to have fewer side effects and increased bioavailability; however, more research is needed to confirm this.4
Why is iron important?
Iron is essential for the formation and function of hemoglobin, which is a protein found in the blood that carries oxygen from the lungs to the rest of the body.1 It also is a component of myoglobin, which brings oxygen to muscle cells and allows them to produce energy for muscle contractions.5 It also helps a variety of other biochemical processes in the body, including electron transport and DNA synthesis.6
What is the RDA for iron?
The Recommended Dietary Allowance (RDA) for iron is 8mg for people above the age of 50. The RDA for people between 19 and 50 years of age is 8mg for men, 18mg for women, 27mg and 9mg for pregnant and lactating women, respectively. The RDA for people between 14 and 18 years of age is 11mg for men and 15mg for women. The RDA for iron is 8mg for children between nine and thirteen years of age, 10mg for children between four and eight years of age, 7mg for toddlers between one and three years of age, 11mg for infants between seven and twelve months, and 0.27mg approximately for infants under 7 months of age.1
These values are given by the National Institutes of Health (NIH), and the RDA represents the daily intake sufficient to meet the dietary needs of 97 to 98 percent of healthy individuals.1 For reference, one cup of canned white beans contains 44 percent of the RDA for iron, 3 ounces of dark chocolate contains 39 percent of the RDA, and 3 ounces of oysters contains 44 percent of the RDA.1
How much is too much?
The daily Upper Limit (UL) for iron is 45mg for people above 13 years of age, and 40mg for children 13 years of age and younger.1 These values are given by the NIH, and the UL represents the maximum daily intake that is unlikely to cause adverse health effects.1
Very high doses of iron supplements may lead to gastrointestinal complications, such as constipation or nausea.1 Iron toxicity can be associated with a variety of symptoms, including arrhythmia, liver complications such as cirrhosis and liver failure, arthritis, diabetes, erectile dysfunction, and issues with a variety of other organs.7 Iron toxicity is particularly dangerous for young children. Accidental ingestion of multivitamins or iron-containing syrups is more common in young children than in the general population.8
High doses of iron can also pose interactions with other medications and supplements. Some examples include levodopa for Parkinson’s disease and restless leg syndrome, levothyroxine for thyroid issues, and proton pump inhibitors such as pantoprazole and lansoprazole.1,2,9,10 It is important to tell your doctor or pharmacist about any supplements that you may be taking in order to reduce the risk of these side effects and interactions.
What are the health benefits of iron?
Aside from the functions that it performs in the body, iron could potentially help prevent anemia-related complications in individuals with chronic conditions. Anemia, which refers to the lack of hemoglobin or red blood cells in the blood and is often associated with iron deficiency, is disproportionately common in certain chronic conditions. These conditions are generally associated with inflammatory symptoms, such as infectious diseases and autoimmune conditions, such as rheumatoid arthritis and inflammatory bowel disease, and this anemia occurs as a result of altered iron distribution due to inflammatory cytokines.1,11
Some evidence suggests that iron deficiency may also play a role in the outcomes of chronic heart failure (CHF); one study found that iron deficiency was associated with poorer health outcomes and higher mortality rates in CHF patients.12 This could potentially suggest that iron supplementation could be beneficial in improving health outcomes in CHF patients with iron-deficiencies; however, more research is needed to determine whether this is valid.
Iron deficiency is relatively common compared to other nutrient deficiencies, as many people may struggle with meeting their RDA for iron. A fairly frequent complication of iron deficiency is iron-deficiency anemia (IDA); this can result in a multitude of symptoms, including chest pain, dizziness, fatigue, difficulty concentrating, headache, pale skin, brittle nails, and more.13 When left untreated, a lower iron status may occur, and these symptoms could potentially lead to other complications, such as heart problems, delays in cognitive functions, and pregnancy complications.13
Some groups are at a greater risk of iron deficiency than others. Pregnant women may be at an increased risk of iron deficiency due to their increased iron requirements. Iron deficiency in pregnant women may potentially be associated with a variety of other complications, such as premature birth and low birthweight; however, more research is needed to confirm this.
People who experience a significant amount of blood loss may potentially be at an increased risk; such groups may include frequent blood donors and people with heavy menstrual bleeding. For example, one study found that iron deficiency was common in frequent blood donors.14 Another study found that, in the participants observed, rates of iron loss were higher in patients with excessive menstrual bleeding than those with normal menstrual bleeding.15
Iron deficiency can fortunately be corrected with iron supplementation, and the type of treatment would likely depend on the type of iron deficiency, cause, and severity. Some examples of potential treatments may include iron supplements, dietary changes, and procedures and intravenous iron therapy in more severe cases.13
If you think you have an iron deficiency or are at an increased risk, consider getting your blood levels tested. As always, consult your doctor before you begin taking any vitamin or mineral supplement to make sure your medications or health conditions don’t make it a serious risk.
- National Institutes of Health Office of Dietary Supplements (2020, February 28). Iron: Fact Sheet for Health professionals. National Institutes of Health. Accessed 2021, March 29, from https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
- Hurrell, R., Egli, I. (2010, May). Iron bioavailability and dietary reference values. Am J Clin Nutr 91(5): 1461S-1467S. Doi: 10.3945/ajcn.2010.28674F.
- Baker, R.D., Greer, F.R. (2010, November). Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). Pediatrics 126(5): 1040-1050. Doi: 10.1542/peds.2010-2576.
- Dull, R.B., Davis, E. (2015, August). Heme iron polypeptide for the management of anaemia of chronic kidney disease. J Clin Pharm Ther 40(4): 386-390. Doi: 10.1111/jcpt.12281.
- Vanek, T., Kohli, A. (2020, July 26). Biochemistry, Myoglobin. StatPearls [Internet]. Accessed 2021, March 29, from https://www.ncbi.nlm.nih.gov/books/NBK544256/
- Abbaspour, N., Hurrell, R., Kelishadi, R. (2014, February). Review on iron and its importance for human health. J Res Med Sci 19(2): 164-174. Accessed from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3999603/
- Cleveland Clinic (2021, January 1). Hemochromatosis (Iron Overload). Cleveland Clinic; Euclid Avenue, Cleveland, Ohio. Accessed 2021, March 29, from https://my.clevelandclinic.org/health/diseases/14971-hemochromatosis-iron-overload
- Yuen, H., Becker, W. (2020, June 30). Iron Toxicity. StatPearls [Internet[. Accessed 2021, March 29, from https://www.ncbi.nlm.nih.gov/books/NBK459224/
- Greene, R.J., Hall, A.D., Hider, R.C. (1990, July). The interaction of orally administered iron with levodopa and methyldopa therapy. J Pharm Pharmacol 42(7): 502-504. Doi: 10.1111/j.2042-7158.1990.tb06605.x.
- Campbell, N.R., Hasinoff, B.B., Stilts, H., Rao, B., Wong, N.C. (1992 December 15). Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med 117(12): 1010-1013. Doi: 10.7326/0003-4819-117-12-1010.
- Weiss, G., Goodnough, L.T. (2005, March 10). Anemia of chronic disease. N Engl J Med 352(10): 1011-1023. Doi: 10.1056/NEJMra041809.
- Klip, I.T., Comin-Colet, J., Voors, A.A., et al. (2013 April). Iron deficiency in chronic heart failure: an international pooled analysis. Am Heart J 165(4): 575-582. Doi: 10.1016/j.ahj.2013.01.017.
- National Heart, Lung, and Blood Institute (n.d.) Iron-deficiency anemia. National Institutes of Health. Accessed 2021, March 30, from https://www.nhlbi.nih.gov/health-topics/iron-deficiency-anemia
- Cable, R.G., Glynn, S.A., Kiss, J.E., et al. (2011 March). Iron deficiency in blood donors: analysis of enrollment data from the REDS-II Donor Iron Status Evaluation (RISE) study. Transfusion 51(3): 511-522. Doi: 10.1111/j.1537-2995.2010.02865.x
- Napolitano, M., Dolce, A., Celenza, G., et al. (2014 April). Iron-dependent erythropoiesis in women with excessive menstrual blood losses and women with normal menses. Ann Hematol 93(4): 557-563. Doi: 10.1007/s00277-013-1901-3.
- Image by Fruzsina Sz from Pixabay