Iron is an essential mineral that contributes to many important physiologic functions in the body. Much of the iron in the body is attached to hemoglobin molecules in red blood cells, thereby delivering oxygen to all of the tissues. Extra iron is stored in the liver, bone marrow, spleen, and muscles.

Significant deficiency in iron leads to anemia. The most common symptoms of anemia are weakness and fatigue. Pregnant women, young women during their reproductive years, and children tend to be at the highest risk of becoming deficient in iron. Anemia may be mild, moderate, or severe and may be caused by significant or prolonged blood loss such as that from a bleeding ulcer, menstruation, severe trauma, surgery, or a malignant tumor. It can also be caused by an iron-poor diet, inefficient absorption of dietary iron, pregnancy, and the rapid growth that takes place during infancy, early childhood, and adolescence.

On the other hand, excessive iron in the body can lead to a condition known as hemochromatosis, which can cause diabetes, liver damage, and discoloration of the skin.

The World Health Organization (WHO) considers iron deficiency the number one nutritional disorder in the world. As many as 80% of the world's population may be iron deficient, while 30% may have iron deficiency anemia.

Anemia

The most important use of iron supplements is to treat anemia caused by iron deficiency. Anemia is low levels of iron in the blood. Iron is important, as it is a key component of hemoglobin, which carries oxygen to our tissues. Anemia can be caused by many conditions, including PMS and menopausal loss, pregnancy, blood donation, bleeding ulcers, surgery (before and after), and chronic diseases such as cancer and kidney failure. Anemia treatment is directed and supervised by a health care provider, who may first search for the underlying reason for the low levels of iron.

Exercise capacity

Low levels of iron can lead to diminished exercise capacity, whether anemia is present or not. Therefore, if your iron stores are low (as measured by your doctor), iron supplements (for example, in a multivitamin or iron supplement) may improve endurance during aerobic activities.

Attention-deficit hyperactivity disorder (ADHD)

Symptoms of iron deficiency (including decreased attention, arousal, and social responsiveness) are similar to symptoms of attention-deficit hyperactivity disorder (ADHD). There is little clinical evidence, however, that iron supplementation improves behavior in children with ADHD who are deficient in iron. Since iron can be toxic in children who are not deficient, there is little justification for its supplementation as a treatment for ADHD in children with normal levels of this mineral. If iron levels are low, a health care provider can determine whether replacement is needed.

Cough associated with ACE inhibitor use

One preliminary clinical study suggested that iron supplementation may soothe and even prevent cough associated with a class of medications known as angiotensin-converting enzyme (ACE) inhibitors, including enalapril (Vasotec), captopril (Capoten), and lisinopril (Zestril or Prinivil). ACE inhibitors are medications commonly used to treat high blood pressure and heart failure, but dry cough is a side effect that leads many people to discontinue their use. Despite this encouraging information, it is premature to conclude that taking iron with ACE inhibitors to reduce dry cough is safe or effective.

Plus, it is important to note that taking ACE inhibitors at the same time as iron may diminish the absorption of this nutrient. Therefore, if used together, the two should be taken at least two hours apart. Also, iron is associated with some risk for heart disease. For this reason, it should not be used by individuals with high blood pressure or heart failure without the consent and supervision of a doctor.

Infants and children

Iron deficiency is a significant public health problem in young children due to their high iron requirements, and iron supplements are therefore often recommended by health care providers. Iron deficiency may increase the risk of lead poisoning in children. However, the use of iron supplementation in lead poisoning is reserved for those individuals who are truly iron deficient or for those individuals with continuing lead exposure, such as continued residence in lead-exposed housing. Do not give iron supplements to infants or children under 18 unless under the supervision of a doctor.

The best dietary sources of iron are liver and other organ meats, lean red meat, poultry, fish, and shellfish (particularly oysters). Iron from these sources is readily absorbed in the intestines.

Other sources of iron include dried beans and peas, legumes, nuts and seeds, whole grains, dark molasses, and green leafy vegetables. However, iron from these sources must be accompanied by certain nutrients for proper absorption. For example, vitamin C helps the absorption of this type of iron while calcium (including all dairy products), bran, tea, and unprocessed whole grain products block its absorption.

In the U.S., grain products such as breads and cereals are fortified with iron to help increase amount in our diet.

Ferrous sulfate is the most common type of iron supplement. Other available forms include ferrous fumarate, ferrous succinate, ferrous gluconate, ferrous lactate, ferrous glutamate, ferric ammonium citrate, and ferrous glycine.

In severe cases of anemia from low levels of iron, or if there is rapid blood loss leading to iron deficiency, iron and blood will be administered intravenously (IV or in the veins) in a hospital setting.

Recommendations for iron are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine of the National Academy of Sciences.

Infants and children (under 18 years of age)

Do not give iron supplements to infants or children under 18 unless under the supervision of a doctor.

For infants 7 – 12 months: The recommended dietary allowance is 11 mg daily.

For children 1 – 3 years: The recommended dietary allowance is 7 mg daily.

For children 4 – 8 years: The recommended dietary allowance is 10 mg daily.

For children 9 – 13 years: The recommended dietary allowance is 8 mg daily.

For male children 14 – 18 years: The recommended dietary allowance is 11 mg daily.

For female children 14 – 18 years: The recommended dietary allowance is 15 mg daily.

Iron in human breast milk is well absorbed by infants. It is estimated that infants can use greater than 50% of the iron in breast milk as compared to less than 12% of the iron in infant formula. The amount of iron in cow's milk is low, and infants poorly absorb it. Feeding cow's milk to infants also may result in gastrointestinal bleeding. For these reasons, cow's milk should not be fed to infants until they are at least 1 year old. The American Academy of Pediatrics (AAP) recommends that infants be exclusively breast fed for the first 6 months of life. Gradual introduction of iron-enriched solid foods should complement breast milk from 7 - 12 months of age. Infants weaned from breast milk before 12 months of age should receive iron-fortified infant formula. Infant formulas that contain from 4 -12 mg of iron per liter are considered iron-fortified.

Adult

For male adults 19 – 50 years: The recommended dietary allowance is 8 mg daily.

For female adults 19 – 50 years: The recommended dietary allowance is 18 mg daily.

For adults 51 years and older: The recommended dietary allowance is 8 mg daily.

For pregnant females ages 14 – 50 years: The recommended dietary allowance is 27 mg daily.

For lactating females ages 14 – 18 years: The recommended dietary allowance is 10 mg daily.

For lactating females ages 19 – 50 years: The recommended dietary allowance is 9 mg daily.

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

The most common side effect from iron supplements is stomach upset, including discomfort, nausea, diarrhea, constipation, and heartburn.

Although not entirely clear, there may be an association between high iron stores and risk of heart disease, cancer (such as breast cancer), and Alzheimer's disease. Similarly, for those with inflammatory bowel disease (Crohn's disease and ulcerative colitis) the areas of the bowel that are inflamed appear to have higher amounts of iron. This is thought to be because iron acts as a pro-oxidant, stimulating the damaging effects in the body of substances known as free radicals.

Iron overload disease, although most commonly an inherited condition called hemochromatosis, may occur in people who consume excessive amounts of iron over a long period of time. Symptoms include skin discoloration, diabetes, and liver damage, among other potential complications. The U.S. Food and Drug Administration (FDA) has established that taking up to 45 mg of iron per day is safe. However, safety for amounts higher than 45 mg per day is not known. Severe iron overdose occurs when amounts of iron equivalent to 50 -100 times greater than the recommended dietary dose are ingested. Such iron toxicity can lead to destruction of cells in the gastrointestinal tract, which can cause vomiting, bloody diarrhea, and even death. Given the severity of potential adverse effects from excessive iron, supplements should be kept in childproof bottles and out of the reach of children.

Intravenous (into the veins) iron, administered in the case of severe anemia in a hospital setting, can lead to headache, fever, swollen lymph nodes, painful joints, hives, worsening of rheumatoid arthritis, and in rare instances a life-threatening allergic reaction known as anaphylaxis.

If you are currently being treated with any of the medications discussed below, you should not use iron without first talking to your health care provider.

Iron may interfere with the absorption of many different medications. For this reason, it is best to take iron supplements at least 2 hours before or 2 hours after taking medications. This is particularly true for the medications listed below.

The following medications may reduce the absorption of iron:

Cholestyramine and Colestipol -- These are two cholesterol-lowering medications known as bile acid sequestrants.

Medications used to treat ulcers or other stomach problems -- Examples of anti-ulcer medications include cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), and nizatidine (Axid). These medications belong to a class of drugs known as H2 receptor blockers. They change the pH in the stomach and subsequently alter the absorption of iron. It is possible that this effect could occur with other antiulcer medications including antacids and proton pump inhibitors, including omeprazole (Prilosec).

Iron decreases the absorption of the following medications:

Tetracyclines -- These are a class of antibiotics that include doxycycline (Vibramycin), minocycline (Minocin), and tetracycline (Sumycin).

Quinolones -- These are a class of antibiotics that include ciprofloxacin (Cipro), norfloxacin (Noroxin), and levofloxacin (Levaquin).

ACE inhibitors -- These are a class of medications used to treat high blood pressure. Examples include captopril (Capoten), enalapril (Vasotec), and lisinopril (Zestril or Prinivil).

Iron may reduce the effectiveness or blood levels of the following medications:

Carbidopa and Levodopa -- Iron lowers blood levels of carbidopa and levedopa (Sinemet ) but it is unclear whether these changes lower the effectiveness of the drugs.

Levothyroxine -- Iron may decrease the effectiveness of this thyroid replacement hormone. A health care provider will monitor thyroid function closely in those taking iron supplements with thyroid medications, including Armour Thyroid and levothyroxine (Synthroid).

Iron levels may be increased by:

Birth control medications -- Birth control medicines, or oral contraceptives, may increase iron levels, thereby decreasing the need for extra iron. Be careful if you are taking oral contraceptives not to take multiple vitamins that contain iron.

Akerele JO, Okhamafe AO. Influence of oral co-administered metallic drugs on ofloxacin pharmacokinetics. J Antimicrob Chemother. 1991;28:87-94.

Balfour JA, Wiseman LR. Moxifloxacin. Drugs. 1999;57(3):363-374.

Baumgaertel A. Alternative and controversial treatments for attention-deficit/hyperactivity disorder. Pediatr Clin of North Am. 1999;46(5):977-992.

Belton N. Iron deficiency in infants and young children. Professional Care of Mother and Child. 1995;5:69–71.

Brouwers J. Drug interactions with quinolone antibacterials. Drug Safety. 1992;7(4):268-281.

Campbell NR, Hasinoff BB, Meddings JB, Anderson WD, Robertson S, Granberg K. Ferrous sulfate reduces cimetidine absorption. Dig Dis Sci. 1993;38(5):950-954.

Christen Y. Oxidative stress and Alzheimer disease. Am J Clin Nutr. 2000;71(suppl):621S-629S.

Dayal M, Barnhart KT. Noncontraceptive benefits and therapeutic uses of the oral contraceptive pill. Semin Reprod Med. 2001;19(4):295-303.

Dietary Guidelines for Americans 2005. Rockville, MD: US Dept of Health and Human Services and US Dept of Agriculture; 2005.

Domellof M. Iron requirements, absorption and metabolism in infancy and childhood. Curr Opin Clin Nutr Metab Care. 2007;10(3):329-35.

Duffy SJ, Biegelsen ES, Holbrook M, et al. Iron chelation improves endothelial function in patients with coronary artery disease. Circulation. 2001;103(23):2799-2804.

Fleming DJ, Jacques PF, Dallal GE, et al. Dietary determinants of iron stores in a free-living elderly population: the Framingham Heart Study. Am J Clin Nutr. 1998;67:722–733.

The Food and Nutrition Information Center. National Agricultural Library (NAL), United States Department of Agriculture's (USDA) Agricultural Research Service (ARS).

Gera T, Sachdev HP, Nestel P, Sachdev SS. Effect of iron supplementation on haemoglobin response in children: systematic review of randomised controlled trials. J Pediatr Gastroenterol Nutr. 2007;44(4):468-86.

Hercberg S, Preziosi P, Galan P. Iron deficiency in Europe. Public Health Nutr. 2001;4(2B):537-545.

Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron depleted, nonanemic women. J Appl Physiol. 2000;88(3):1103-1111.

Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press. January 9, 2001.

Jensen JT, Speroff L. Health benefits of oral contraceptives. Obstet Gynecol Clin North Am. 2000;27(4):705-721.

Kara M, Hasinoff BB, McKay DW, et al. Clinical and chemical interactions between iron preparations and ciprofloxacin. Br J Clin Pharmacol. 1991;31(3):257-261.

Killip S, Bennett JM, Chambers MD. Iron deficiency anemia. Am Fam Physician. 2007;75(5):671-8.

Lee SC, Park SW, Kim DK, Lee SH, Hong KP. Iron supplementation inhibits cough associated with ACE inhibitors. Hypertension. 2001;38(2):166-170.

Li RC, Lo KN, Lam JS, et al. Effects of order of magnesium exposure on the postantibiotic effect and bactericidal activity of ciprofloxacin. J Chemother. 1999;11(4):243-247.

Liehr JG, Jones JS. Role of iron in estrogen-induced cancer. Curr Med Chem. 2001;8(7):839-849.

Lih-Brody L, Powell Sr, Collier KP, et al. Increased oxidative stress and decreased antioxidant defenses in mucosa of inflammatory bowel disease. Dig Dis Sci. 1996;41(10):2078-2086.

Mittal R, Marwaha N, Basu S, Mohan H, Ravi Kumar A. Evaluation of iron stores in blood donors by serum ferritin. Indian J Med Res. 2006;124(6):641-6.

Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs. 1976;11(1):45-54.

Okhamafe AO, Akerele JO, Chukuka CS. Pharmacokinetic interactions of norfloxacin with some metallic agents. Int J Pharmaceutics. 1991;68:11-16.

Say AE, Gursurer M, Yazicioglu MV, Ersek B. Impact of body iron status on myocardial perfusion, left ventricular function, and angiographic morphologic features in patients with hypercholesterolemia. Am Heart J. 2002;143(2):257-264.

Schaefer JP, Tam Y, Hasinoff BB, et al. Ferrous sulphate interacts with captopril. Br J Clin Pharmacol. 1998;46(4):377-381.

Sempos C, Looker AC, Gillum RE, McGee DL, Vuong CV, Johnson CL. Serum ferritin and death from all causes of cardiovascular disease: The NHANES II Mortality Study. Ann Epidemiol. 2000;10(7):441-448.

Sever Y, Ashkenazi A, Tyano S, Weizman A. Iron Treatment in children with attention deficit Hyperactivity disorder: a preliminary report. Neuropsychobiology. 1997; 35:178-180.

Shakir KM, Chute JP, Aprill BS, Lazarus AA. Ferrous sulfate-induced increase in requirement for thyroxine in a patient with primary hypothyroidism. South Med J. 1997;90(6):637-639.

Sturniolo GC, Mestriner C, Lecis PE, et al. Altered plasma and mucosal concentrations of trace elements and antioxidants in active ulcerative colitis. Scand J Gastroenterol. 1998;33:644-649.

Tappel A. Heme of consumed red meat can act as a catalyst of oxidative damage and could initiate colon, breast and prostate cancers, heart disease and other diseases.Med Hypotheses. 2007;68(3):562-4.

Torkos S. Drug-nutrient interactions: a focus on cholesterol-lowering agents. Int J Integrative Med. 2000;2(3):9-13.

Tyrer LB. Nutrition and the pill. J Reprod Med. 1984;29(7 Suppl):547-550.

Tzonou A, Lagiou P, Trichopoulou A, et al. Dietary iron and coronary heart disease: a study from Greece. Am J Epidemiol. 1998;147:161–166.