Iron: An Important Mineral in Your Diet

By Greatorex, Susan

Iron is a metal that is essential for life. It is a part of proteins and enzymes found throughout your body, including hemoglobin and myoglobin, both of which help carry oxygen in the blood, according to the Office of Dietary Supplements (ODS). Iron is an important component of your muscles, and it helps regulate the growth of cells. Iron comes from foods you eat. Your body stores excess iron for future use.

Iron in foods comes in two forms: heme and nonheme. Heme iron is found in animal foods that originally contained hemoglobin and myoglobin, such as 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 percent of the iron in foods, but several factors can affect the actual amount absorbed, the ODS says. One factor is the type of iron. Heme iron is absorbed more efficiently than nonheme (up to 35 percent is absorbed) and its absorption is not affected by other nutrients in food. From 2 to 20 percent of nonheme iron is absorbed from food. These nutrients decrease the amount of nonheme absorbed: tannins (found in tea), calcium, polyphenols, phytates (found in legumes and whole grains) and some soybean proteins. Adding meat and vitamin C to your meals will improve the absorption of 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 protects you from the toxic effects of too much iron.

How much iron?

The Recommended Dietary Allowance 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 breast-feeding 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 recommendation on iron intake.

Recommended Dietary Allowances for Iron for Infants (7 to 12 months), Children, and Adults

Age

Males

(mg/day)

Females

(mg/day)

Pregnancy

(mg/day)

Lactation

(mg/day)

9 to 13 years

8

8

N/A

N/A

14 to 18 years

11

15

27

10

19 to 50 years

8

18

27

9

51+ years

8

8

N/A

N/A

Source: Office of Dietary Supplements, National Institutes of Health

If you don't get enough iron from the food you eat, your body will use the iron it has stored. If your diet continues to be deficient in iron, your body will eventually use up all the stored iron, and it won't be able to maintain hemoglobin at a normal level, the ODS says. This condition is called iron deficiency anemia. Other factors that can lead to iron deficiency anemia are heavy menstrual blood flow, kidney failure, a deficiency of vitamin A (which helps your body extract stored iron) and certain gastrointestinal disorders that interfere with absorption of iron from food. Healthy adult men and postmenopausal women normally don’t lose much iron and have a low risk for iron deficiency. Some medications decrease iron levels. These include ACTH (a hormone), colchicine, deferoxamine, methicillin and testosterone.

People who regularly engage in intense exercise -- female athletes, distance runners, vegetarian athletes -- may need 30 percent more iron than normal. If you are an athlete, you should talk to your health care provider about the need for extra iron.

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