Iron is a mineral that is essential for life. It is a part of proteins and enzymes found in your body. It’s found in hemoglobin and myoglobin, both of which help carry oxygen in the blood. Iron is an important part of your muscles, and it helps regulate the growth of cells. Iron comes from foods you eat. Any excess iron is stored in the body’s tissues for future use.
Iron in foods comes in 2 forms: heme and nonheme. Heme iron is found in animal foods that contain hemoglobin and myoglobin. This includes red meat, fish, and poultry. Nonheme iron is found in plants, such as lentils and other beans. Nonheme iron is the form of iron added to iron-enriched and iron-fortified foods.
Healthy adults absorb about 10% to 15% of the iron in foods. But several factors can affect the actual amount absorbed. One factor is the type of iron. Heme iron is absorbed more easily than nonheme. And the absorption of heme iron is not affected by other nutrients in food. About 35% of heme iron is absorbed from food. Only about 2% to 20% of nonheme iron is absorbed from food.
Some chemicals make it harder to absorb nonheme iron. These include:
Tannins in tea
Phytates in legumes and whole grains
Some soybean proteins
Adding meat and vitamin C to your meals will make it easier for your body to absorb nonheme iron.
Another factor that affects absorption of iron from food is the amount of iron stored in your body. If you have enough iron stored, you absorb less from food. This helps protect you from the toxic effects of too much iron.
The dietary reference intake (DRI) for iron for healthy adults is based on your age and gender. Menstruating women need more iron because some iron is lost in menstrual periods. Women who are breastfeeding also need slightly more iron. Pregnant women need about twice the daily iron as women who aren't pregnant. If you are pregnant, follow your health care provider's advice on iron intake.
9 to 13 years
14 to 18 years
19 to 50 years
Source: Office of Dietary Supplements, National Institutes of Health
People who regularly do intense exercise may need 30% more iron than normal. These include female athletes, distance runners, and athletes who are vegetarian. If you are an athlete, talk with your health care provider about your iron needs.
If you don't get enough iron from the foods you eat, your body will use the iron it has stored. If your diet continues to be low in iron, your body will use up all the stored iron. Your blood will then not be able to keep hemoglobin at a normal level. This is called iron-deficiency anemia. Healthy adult men and postmenopausal women normally don’t lose much iron. They are at low risk for iron deficiency. But factors that make it more likely for you to have iron-deficiency anemia include:
Heavy menstrual blood flow
Certain gastrointestinal disorders that interfere with absorption of iron from food
Deficiency of vitamin A. Vitamin A helps your body use stored iron.
Taking medicines like the hormone ACTH, colchicine, deferoxamine, methicillin, or testosterone
Symptoms of iron deficiency include:
Shortness of breath and dizziness
Chest pain (only if anemia is severe)
Symptoms of long-term iron deficiency include:
A burning sensation in the tongue, or a smooth tongue
Sores at the corners of the mouth
Cravings for a specific nonfood substances, such as licorice, chalk, or clay (pica)
Spoon-shaped fingernails and toenails
If your diet can't restore iron levels to normal, you may need an iron supplement. There are 2 kinds: ferrous and ferric. Ferrous iron salts are absorbed more easily. These include ferrous fumarate, ferrous sulfate, and ferrous gluconate. Iron supplements may cause side effects, such as nausea, vomiting, constipation, diarrhea, dark-colored stools, and abdominal discomfort. If you need an iron supplement, ask your health care provider how much you should take and for how long. You may have follow-up blood tests to check your iron levels.
Keep iron supplements away from children. Even 200 mg of iron may be fatal to a child. Call a poison control center or 911 right away if you suspect a child has taken iron supplements.
Iron overload is when you have too much iron in your blood and stored in organs like the liver and heart. Some people have no symptoms of iron overload. But in other cases symptoms can include:
Lack of energy
Loss of sex drive
Iron overload can cause many complications. Organ damage from iron overload can cause liver disease. This can include an enlarged liver, cirrhosis, cancer, or liver failure. It can also cause damage to the pancreas, which may cause diabetes. It can also cause heart problems, such as irregular heart rhythms or congestive heart failure. It can also cause thyroid deficiency, and it can damage the adrenal glands.
Iron overload is more of a risk for certain people. Don’t take iron supplements if you:
Have the genetic disorder hemochromatosis
Are a postmenopausal woman
Have sickle cell disease, myelodysplastic syndrome, or thalassemia
Have another health condition that requires frequent blood transfusions
Are taking methyldopa or chloramphenicol
Treatment for iron overload includes stopping iron supplements. Iron levels in the blood may need to be lowered. This can be done by removing blood on a periodic basis. Or it can be done with iron-chelating medication. This is a chemical that combines with iron in the bloodstream. Then the iron can be more easily removed from the body.