What is iron and how does the body use it?

Iron is a chemical element (symbol Fe) that our bodies need to function correctly. Most of the iron in our bodies is found in the blood as hemoglobin, which is a protein that carries oxygen to the body's tissues.

Dietitians often divide iron into two types — heme and nonheme:

  • Heme iron is found in animal products
  • Nonheme iron is plant-based

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How much iron do I need in my diet?

Group RDA (mg)
Men 19+ 8
Menstruating women 18†
Pregnant Women 27
Lactating Women 9
Post-menopausal Women 8
Source: National Institutes of Health1
† Nutrition Facts label recommended daily value

These recommendations assume a mix of heme and nonheme sources of iron. Vegetarians should multiply the recommendations by 1.8 since the body does not absorb nonheme sources as easily as heme sources.

Are you eating enough iron? Keep a food diary and find out. Track iron!

What are good sources of iron?

Heme iron is found in:

  • Beef and beef livers
  • Chicken, especially dark meat and chicken livers
  • Turkey, primarily dark meat
  • Light canned tuna in water

Nonheme iron is found in:

  • Beans such as kidney, lima, pinto, black, and navy beans
  • Fermented soy-based foods such as tofu
  • Lentils
  • Nuts and seeds
  • Fortified cereals
  • Spinach
  • Raisins

Iron is absorbed better when consumed with acidic foods, especially those high in vitamin C. Iron is poorly absorbed when consumed with:

  • Tannins and polyphenols found in tea, coffee, and cocoa
  • Calcium found in dairy products and fortified foods
  • Phytates found in seeds and whole grains
Example Serving Size mg
Quaker Squares CerealFortified 1 cup 16.2
Lentils 1 cup 6.7
Beef Liver 4 oz 5.5
Navy Beans 1 cup 4.5
Soy Beans (Shelled) 1 cup 4.5
Lima Beans 1 cup 4.3
Pinto Beans 1 cup 3.6
Black Beans 1 cup 3.6
Ground Beef 4 oz 2.7

What is iron deficiency?

Iron deficiency is the most common nutritional disorder in the world. It is found most often in menstruating women, pregnant women, repeat blood donors, vegetarians, and older toddlers. Iron deficiency can be caused by not eating enough iron, not absorbing enough iron, or excessive blood loss. When a person's diet does not contain enough iron, the body uses its iron reserves. As these reserves become depleted, hemoglobin levels drop — a condition called anemia. Anemia causes symptoms such as fatigue, a swollen tongue, a suppressed immune system, decreased mental functioning, difficulty regulating body temperature, and social development difficulties in children.

What is iron toxicity?

Iron toxicity occurs when the body stores too much iron. When iron stores are full, the body starts to deposit the mineral in organs and tissues, including the heart and liver. Iron toxicity can result in long-term damage to these organs, which can result in death. Toxicity can occur in children who consume more than 40 mg per day and adults who consume more than 45 mg per day.

Additional Resources

  1. Iron Fact Sheet. National Institutes of Health.

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