Iron

Iron is a mineral. Most of the iron in the body is found in the hemoglobin of red blood cells and in the myoglobin of muscle cells. Iron is needed for transporting oxygen and carbon dioxide. It also has other important roles in the body.

People take iron supplements for preventing and treating low levels of iron (iron deficiency) and the resulting iron deficiency anemia. In people with iron deficiency anemia, the red blood cells can’t carry enough oxygen to the body because they don’t have enough iron. People with this condition often feel very tired.

Iron is also used for improving athletic performance and treating attention deficit-hyperactivity disorder (ADHD) and canker sores. Some people also use iron for Crohn's disease, depression, fatigue, and the inability to get pregnant.

Women sometimes take iron supplements to make up for iron lost in heavy menstrual periods. Iron-rich foods, such as pork, ham, chicken, fish, beans, and especially beef, liver, and lamb are also used.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for IRON are as follows:

• Attention deficit-hyperactivity disorder (ADHD). Developing research shows that taking iron sulfate (an iron-containing chemical compound) improves some measures of attention deficit-hyperactivity disorder (ADHD) in children with iron deficiency after 1-3 months of treatment.
• Fatigue. There is some early evidence that iron supplements might improve unexplained fatigue in non-anemic women.
• Improving athletic performance.
• Canker sores.
• A digestive tract disease called Crohn's disease.
• Depression.
• Female infertility.
• Heavy menstrual bleeding.
• Restless leg syndrome.
• Other conditions.

More evidence is needed to rate iron for these uses.

Iron helps red blood cells deliver oxygen from the lungs to cells all over the body. Once the oxygen is delivered, iron then helps red blood cells carry carbon dioxide waste back to the lungs to be exhaled. Iron also plays a role in many important chemical reactions in the body.

Iron is LIKELY SAFE for most people when it is used appropriately. However, it can cause side effects including stomach upset and pain, constipation or diarrhea, nausea, and vomiting. Taking iron supplements with food seems to reduce some of these side effects. But food can also reduce how well the body absorbed iron. Iron should be taken on an empty stomach if possible. But if it causes too many side effects, it can be taken with food. Try to avoid taking it with foods containing dairy products, coffee, tea, or cereals.

There are many forms of iron products such as ferrous sulfate, ferrous gluconate, ferrous fumarate, and others. Some products, such as those containing polysaccharide-iron complex (Niferex-150, etc), claim to cause fewer side effects than others. But there is no reliable evidence to support this claim.

Some enteric coated or controlled release iron products might reduce nausea for some people; however, these products also have less absorption by the body.

Liquid iron supplements may blacken teeth.

High doses of iron are UNSAFE, especially for children. Iron is the most common cause of poisoning deaths in children. Doses as low as 60 mg/kg can be fatal. Iron poisoning can cause many serious problems including stomach and intestinal distress, liver failure, dangerously low blood pressure, and death. If you suspect an adult or child has taken more than the recommended amount of iron, call your healthcare professional or the nearest poison control center immediately.

There is some concern that high intake of iron might increase the chance of developing heart disease. Some studies show that people with high intake of iron, especially from food sources such as red meat, are more likely to have heart disease. This may be especially true for people with type 2 diabetes. But this is controversial. Other studies do not show that iron increases the chance of heart disease. It is too soon to tell for sure if iron increases the chance of heart disease.

Special precautions & warnings:

Pregnancy and breast-feeding: Iron is LIKELY SAFE for pregnant and breast-feeding women who have enough iron stored in their bodies when used in doses below the tolerable upper intake level (UL) of 45 mg per day of elemental iron. The UL is the highest level of intake at which no harmful side effects are expected. However, iron is LIKELY UNSAFE when taken by mouth in high doses. If you don’t have iron deficiency, don’t take more than 45 mg per day of elemental iron per day. Higher doses frequently cause stomach and intestinal side effects such as nausea and vomiting. High levels of hemoglobin at the time of delivery are associated with bad pregnancy outcomes. Hemoglobin is the molecule in red blood cells that contains iron.

Diabetes: There is concern that a diet that is high in iron might increase the risk of heart disease in women with type 2 diabetes, although this has not been proven. If you have diabetes, discuss your iron intake with your healthcare provider.

Stomach or intestinal ulcers: Iron might cause irritation and make these conditions worse. Use iron with care.

Intestinal inflammation, such as ulcerative colitis or Crohn’s disease: Iron might cause irritation and make these conditions worse. Use iron with care.

Hemoglobin disease, such as thalassemia: Taking iron might cause iron overload in people with these conditions. If you have a hemoglobin disease, don’t take iron unless directed to do so by your healthcare provider.

Premature infants: Giving iron to premature infants with low blood levels of vitamin E can cause serious problems. The vitamin E deficiency should be corrected before giving iron. Talk with your healthcare provider before giving iron to a premature infant.

Moderate

Minor

Acacia forms an insoluble gel with some forms of iron. It isn't known whether this leads to a significant interaction when the two are ingested together.

Beta-carotene may help the body take in (absorb) iron from iron-fortified wheat and corn flour, and rice. But taking extra beta-carotene probably wouldn't make much difference in iron absorption unless levels of beta-carotene are too low.

Calcium makes it harder for the body to absorb iron either from food or supplements. However, in people who have enough stored iron, this probably isn't a problem. But if you are iron deficient or might become iron deficient, minimize this interaction by separating your intake of calcium and iron. Don't take calcium supplements at mealtime or when you take iron supplements.

Taking riboflavin supplements may improve the way iron supplements work in some people with anemia. But this effect is probably significant only in people with low levels of riboflavin.

Soy protein seems to reduce the body's ability to take in iron. If you are iron deficient, choose fermented soy products. They seem to interfere with iron absorption less. However, the real importance of the interaction between soy and iron has not been determined.

Vitamin A appears to be involved in moving iron from where it is stored in the body to red blood cells developing in the bone marrow. There, iron is used to build hemoglobin, the molecule in red blood cells that carries oxygen. Giving vitamin A supplements seems to improve iron levels in people whose iron levels are too low. Developing research suggests that vitamin A and beta-carotene may improve iron absorption from iron-fortified wheat and corn flour, and rice. It's unlikely that giving vitamin A supplements would have significant effects on iron status in people who have enough vitamin A to start with.

Taking vitamin C and iron together helps the body absorb the iron. It doesn't matter whether the vitamin C comes from food or a supplement. But, taking a vitamin C supplement to improve absorption of iron probably isn't necessary for most people, especially if their diet contains plenty of vitamin C.

Under some circumstances iron can interfere with how the body absorbs zinc, and vice versa. But food stops the interaction. To get maximum benefit from zinc or iron supplements, it's a good idea to take them with food.

Taking iron supplements with coffee or tea can reduce the amount of iron the body absorbs. These beverages can even reduce the amount of iron the body absorbs from food. These effects might contribute to iron deficiency anemia, especially in people with other risk factors.

Calcium in dairy products such as milk and cheese can reduce the absorption of iron from food and supplements. This probably isn't a problem for people who have enough iron stored in their bodies. But if you need iron, take iron supplements with a meal that is relatively low in dairy products whenever possible. People may say you'll get the best absorption of iron on an empty stomach, but this increases the risk of stomach irritation. Don't risk it. You're better off taking iron with a low-calcium meal.

Taking iron with food can decrease how much iron is absorbed by the body by 40% to 50%. For best absorption, iron should be taken on an empty stomach. But some people may not be able to tolerate this due to side effects such as upset stomach or nausea. If iron needs to be taken with food to reduce side effects, avoid dairy foods, coffee, tea, or cereals.

The following doses have been studied in scientific research:

BY MOUTH:

• For treating iron-deficiency in adults: 50-100 mg elemental iron three times daily. For treating children with iron deficiency anemia: the dose is 4-6 mg/kg per day divided into three doses. For both adults and children, 2-3 months of treatment can reverse anemia but might not rebuild the body’s supply of stored iron. Therefore, treatment is usually continued another 6 months to build up the body’s iron reserves.
• For preventing iron deficiency in children, the American Academy of Pediatrics recommends iron supplements for some groups. For breast-fed infants, elemental iron 1 mg/kg/day is recommended from ages 4-6 months. Infants from 6-12 months should get 11 mg/day from food or supplements. For pre-term infants, 2 mg/kg/day for the first year is recommended. This should be continued until the baby is switched to formula or otherwise getting enough iron from food sources. Formula-fed children get enough iron from infant formula. Toddlers aged 1-3 years usually get enough iron from foods to meet the recommended daily amount of 7 mg/day; however, a supplement can be added if needed.
• For improving learning and thinking skills in iron-deficient adolescents: 650 mg ferrous sulfate twice daily.
• For cough caused by ACE inhibitors: 256 mg ferrous sulfate daily.

The adequate intake (AI) of iron for infants 6 months of age and less is 0.27 mg/day. For older infants and children, the recommended daily allowances (RDAs) for iron are: Infants 7 to 12 months, 11 mg/day; children 1 to 3 years, 7 mg/day; 4 to 8 years, 10 mg/day; 9 to 13 years, 8 mg/day; boys 14 to 18 years, 11 mg/day; girls 14 to 18 years, 15 mg/day. For adults, the RDA for iron is 8 mg/day for men ages 19 and older, and women ages 51 and older. For women 19 to 50 years, the RDA is 18 mg/day. For pregnant women, the RDA is 27 mg/day. For breast-feeding women, the RDA is 10 mg/day for ages 14 to 18 years, and 9 mg/day for ages 19 to 50.

Tolerable Upper Intake Levels (UL), the highest intake at which no unwanted side effects are expected, for iron are: infants and children birth to age 13, 40 mg/day; people age 14 and older (including pregnancy and breastfeeding), 45 mg/day. UL recommendations do not apply to people under medical supervision for iron deficiency.

There are many forms of iron supplements which contain different amounts of elemental iron: 1 gram of ferrous gluconate = 120 mg elemental iron (12% iron); 1 gram of ferrous sulfate = 200 mg elemental iron (20% iron); 1 gram of ferrous fumarate = 330 mg elemental iron (33% iron). The effectiveness and side effects are similar for these different forms when used in equal doses of elemental iron.

Atomic Number 26, Carbonate de Fer Anhydre, Citrate de Fer, Elemental Iron, Fe, Fer, Fer Élémentaire, Ferric Orthophosphate, Ferrous Carbonate Anhydrous, Ferrous Citrate, Ferrous Fumarate, Ferrous Gluconate, Ferrous Pyrophosphate, Ferrous Sulfate, Ferrum Phosphoricum, Fumarate de Fer, Gluconate de Fer, Glycérophosphate de Fer, Heme Iron Polypeptide, Hierro, Iron Glycerophosphate, Orthophosphate de Fer, Orthophosphate Ferrique, Numéro Atomique 26, Polypeptide de Fer de Heme, Pyrophosphate de Fer, Sulfate de Fer.

To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.methodology (http://www.nlm.nih.gov/medlineplus/druginfo/natural/methodology.html).

To see all references for the Iron page, please go to http://www.nlm.nih.gov/medlineplus/druginfo/natural/912.html.

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Page last updated: 27 September 2012