Definition

Iron is a mineral found in every cell of the body. Iron is considered an essential mineral because it is needed to make hemoglobin, a part of blood cells. The body cannot make it, so it must be taken in with the food we eat.

Alternative Names

Diet - iron; Ferric acid; Ferrous acid; Ferritin

Function

The human body needs iron to make the oxygen-carrying proteins hemoglobin and myoglobin. Hemoglobin is found in red blood cells. Myoglobin is found in muscles.

Food Sources

The best sources of iron include:

• Dried beans
• Dried fruits
• Eggs (especially egg yolks)
• Iron-fortified cereals
• Liver
• Lean red meat (especially beef)
• Oysters
• Poultry, dark red meat
• Salmon
• Tuna
• Whole grains

Reasonable amounts of iron are also found in lamb, pork, and shellfish.

Iron from vegetables, fruits, grains, and supplements is harder for the body to absorb. Plant sources include:

Dried fruits:

• Prunes
• Raisins
• Apricots

Legumes:

• Lima beans
• Soybeans
• Dried beans and peas
• Kidney beans

Seeds:

• Almonds
• Brazil nuts

Vegetables:

• Broccoli
• Spinach
• Kale
• Collards
• Asparagus
• Dandelion greens

Whole grains:

• Wheat
• Millet
• Oats
• Brown rice

If you mix some lean meat, fish, or poultry with beans or dark leafy greens at a meal, you can improve absorption of vegetable sources of iron up to three times. Foods rich in vitamin C (such as citrus, strawberries, tomatoes, and potatoes) also increase iron absorption. Cooking foods in a cast-iron skillet can also help to increase the amount of iron provided.

Some foods reduce iron absorption. For example, commercial black or pekoe teas contain substances that bind to dietary iron so it cannot be used by the body.

Side Effects

LOW IRON LEVEL

The human body stores some iron to replace any that is lost. However, a low iron level over a long period of time can lead to iron deficiency anemia. Symptoms include lack of energy, shortness of breath, headache, irritability, dizziness, or weight loss. Physical signs of lack of iron are a pale tongue and spoon-shaped nails.

Those at risk for a low iron level include:

• Women who are menstruating, especially if they have heavy periods
• Women who are pregnant or who have just had a baby
• Long-distance runners
• People with any type of bleeding in the digestive tract (for example, a bleeding ulcer)
• People who frequently donate blood
• People with gastrointestinal conditions that make it hard to absorb nutrients from food

Babies and young children are at risk for a low iron level if they do not get the right foods. Babies moving to solid foods should eat iron-rich foods. Infants are born with enough iron to last about six months. An infant's extra iron needs are met by breast milk. Infants who are not breastfed should be given an iron supplement or iron-fortified infant formula.

Children between age 1 and 4 grow fast. This uses up iron in the body. Children of this age should be given iron-fortified foods or an iron supplement.

Milk is a very poor source of iron. Children who drink large quantities of milk and avoid other foods may develop "milk anemia." The recommended milk intake is 2 to 3 cups (480 to 720 milliliters) per day for toddlers.

TOO MUCH IRON

The genetic disorder called hemochromatosis affects the body's ability to control how much iron is absorbed. This leads to too much iron in the body. Treatment consists of a low-iron diet, no iron supplements, and phlebotomy (blood removal) on a regular basis.

It is unlikely that a person would take too much iron. However, children can sometimes develop iron poisoning by swallowing too many iron supplement pills or liquid. Symptoms of iron poisoning include:

• Fatigue
• Anorexia
• Dizziness
• Nausea
• Vomiting
• Headache
• Weight loss
• Shortness of breath
• Grayish color to the skin

Recommendations

Dosages for iron, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

• Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.
• Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.

Dietary Reference Intakes for iron:

Infants and children

• Younger than 6 months: 0.27 milligrams per day (mg/day)*
• 7 months to 1 year: 11 mg/day
• 1 to 3 years: 7 mg/day
• 4 to 8 years: 10 mg/day

*AI or Adequate Intake

Males (RDA)

• 9 to 13 years: 8 mg/day
• 14 to 18 years: 11 mg/day
• Age 19 and older: 8 mg/day

Females (RDA)

• 9 to 13 years: 8 mg/day
• 14 to 18 years: 15 mg/day
• 19 to 50 years: 18 mg/day
• 51 and older: 8 mg/day
• Pregnant women of all ages: 27 mg/day
• Lactating women 19 to 30 years: 9 mg/day (age 14 to 18: 10 mg/day)

Women who are pregnant or producing breast milk may need different amounts of iron. Ask your health care provider what is right for you.

References

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205.

Maqbool A, Parks EP, Shaikhkhalil A, Panganiban J, Mitchell JA, Stallings VA. Nutritional requirements. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 55.

National Institutes of Health website. Iron: fact sheet for health professionals. ods.od.nih.gov/factsheets/Iron-HealthProfessional/. Updated April 5, 2022. Accessed February 21, 2023.