Everything you need to know about iron

Everything you need to know about iron

Iron is a mineral essential for the proper functioning of hemoglobin, a protein that is required to hold oxygen in the blood. Iron also plays a part in a number of other important body processes.

A lack of iron in the blood can contribute to a number of serious health issues including anemia and iron deficiency. Approximately 10 million people in the United States have low levels of iron and about 5 million of them have been diagnosed with iron deficiency anemia.

This feature of the Nccmed Knowledge Center is part of a series of articles about the health benefits of common vitamins and minerals. It offers an in-depth look at the recommended consumption of iron, its possible health benefits, high-iron foods and any possible health risks associated with eating too much iron.

Important facts about iron

  • The Recommended Daily Allowance (RDA) varies between ages, but women who are pregnant require the most.
  • Iron promotes healthy pregnancy, increased energy, and better athletic performance. Iron deficiency is most common in female athletes.
  • Canned clams, fortified cereals, and white beans are the best sources of dietary iron.
  • Too much iron can increase the risk of liver cancer and diabetes.

Recommended intake

A person’s age and sex can affect the amount of iron they need in their diet.
A person’s age and sex can affect the amount of iron they need in their diet.

The Recommended Daily Allowance (RDA) for elemental iron is based on age and sex of a person. Vegetarians have different demands for iron, too.


  • 0 to 6 months: 0.27 milligrams (mg)
  • 7 to 12 months: 11 mg


  • 1 to 3 years: 7 mg
  • 4 to 8 years: 10 mg


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


  • 9 to 13 years: 8 mg
  • 14 to 18 years: 15 mg
  • 19 to 50 years: 18 mg
  • 51 years and older: 8 mg
  • During pregnancy: 27 mg
  • When lactating between 14 and 18 years of age: 10 mg
  • When lactating at older than 19 years: 9 mg

Iron supplements can be effective because it is difficult for people to take enough iron by dietary steps alone, such as a plant-based diet. It is best to try to eat enough alone in the diet by eliminating or reducing factors that may impede the absorption of iron and the intake of iron-rich food.

That is because many iron-rich foods often contain an abundance of other beneficial nutrients that function together to promote optimal health.


Iron helps maintain many essential functions within the body, including overall strength and concentration, gastrointestinal processes, the immune system, and body temperature control.

Often the benefits of iron go unnoticed until a person doesn’t get enough. Iron deficiency anemia can lead to exhaustion, palpitations in the heart, pale skin and breathlessness.

Healthy pregnancy

Iron is important for maintaining a healthy pregnancy.
Iron is important for maintaining a healthy pregnancy.

Throughout the pregnancy, blood volume and red blood cell production increase significantly to supply oxygen and nutrients to the rising fetus. It also raises demand for iron. Although the body normally maximizes the absorption of iron during pregnancy, inadequate iron intake or other factors that influence the absorption of iron can lead to iron deficiency.

During pregnancy, low iron intake raises the risk of premature birth and low birth weight, as well as low iron reserves and decreased cognitive or behavioral growth in infants. Pregnant women with low iron could be more vulnerable to infection because iron strengthens the immune system too.

It is clear that iron supplements are required for pregnant women as well as iron deficient women. Research on the possibility of prescribing additional iron to all pregnant women, including those with normal iron levels, is ongoing however. It is suggested that all pregnant women, regardless of their iron levels, will take 30 to 60 milligrams ( mg) of iron supplements on each day of their pregnancy.


Lack of iron in the diet can affect the efficiency with which the body is using energy. Iron provides the muscles and brain with oxygen and is important for both mental and physical health. Low levels of iron can lead to lack of concentration, increased irritability and decreased stamina.

Great results on competition

Iron deficiency among athletes , particularly young female athletes, is more common than in individuals who do not lead an active lifestyle.

It appears to be particularly true of women endurance athletes, such as long-distance runners. Several experts say that female endurance athletes will add up to the existing iron intake RDA an additional 10 mg of elemental iron per day.

Iron deficiency in athletes decreases athletic efficiency and weakens function in the immune system. A lack of hemoglobin may significantly decrease performance during physical exertion, as it decreases the ability of the body to transport oxygen to muscles.


Iron has poor bioavailability, which means the small intestine doesn’t absorb large quantities readily. This reduces its flexibility for use and increases risk of deficiency.

Absorption success depends on a number of factors including:

  • the source of iron
  • other components of the diet
  • gastrointestinal health
  • use of medications or supplements
  • a person’s overall iron status
  • presence of iron promoters, such as vitamin C

For several nations, iron fortifies the wheat goods and infant formulas.

There are two types of dietary iron, called heme and non-heme. Animal food products, meat and seafood included, contain heme iron. The body absorbs heme iron with greater ease.

Non-heme iron, the kind found in plants, allows the body to take several measures to consume it. Plant-based iron sources include beans, nuts, soybeans, vegetables and fortified grains.

Heme iron bioavailability from animal products can be as high as 40 percent. Nonetheless, non-heme iron from plant-based sources has between 2 and 20 percent bioavailability. For this reason, the RDA for vegetarians is 1.8 times higher than for those who eat meat to make up for the lower absorption level from plant-based foods.

Eating foods that are high in vitamin C alongside non-heme iron sources will significantly improve the absorption of iron.

It is also important to consider components of food and medicines which block or reduce iron absorption when following a vegetarian diet, such as:

  • proton pump inhibitors and omeprazole, used to reduce the acidity of stomach contents
  • polyphenols in cereals and legumes, as well as in spinach
  • tannins in coffee, tea, some wine, and certain berries
  • phosphates in carbonated beverages, such as soda
  • phytates in beans and grains

Some of the best sources of iron include:

Clams are an excellent source of iron.
Clams are an excellent source of iron.
  • Canned clams: 3 ounces (oz) provides 26 milligrams (mg) of iron.
  • Fortified, plain, dry cereal oats: 100 g provides 24.72 mg.
  • White beans: One cup provides 21.09.
  • Dark chocolate (45 to 69 percent cacao): One bar provides 12.99 mg.
  • Cooked Pacific oysters: 3 oz provides 7.82 mg.
  • Cooked spinach: One cup provides 6.43 mg.
  • Beef liver: 3 oz provides 4.17 mg.
  • Boiled and drained lentils: Half a cup provides 3.3 mg.
  • Firm tofu: Half a cup provides 2.03 mg.
  • Boiled and drained chickpeas: Half a cup provides 2.37 mg.
  • Canned, stewed tomatoes: Half a cup provides 1.7 mg.
  • Lean, ground beef: 3 oz provides 2.07 mg.
  • Medium baked potato: This provides 1.87 mg.
  • Roasted cashew nuts: 3 oz provides 2 mg.

Calcium can speed up absorption of both heme and non-heme iron. In most cases, a standard Western-style, diverse diet is considered healthy in terms of iron absorption enhancers and inhibitors.


In adults, doses of elemental iron per day for oral iron supplementation can be as high as 60 to 120 mg. Such doses usually refer to pregnant women who have serious iron deficiencies. An upset stomach is a common side effect of supplementing iron so it can help to separate doses during the day.

Adults with a healthy digestive system have a very low risk of the dietary iron overload.

Individuals with a genetic disorder called hemochromatosis are at high risk of overloading iron, because they consume much more iron from food compared to those without the condition.

Which can contribute to iron accumulation in the liver and other organs. This can also cause free radicals to be produced that damage cells and tissues, including the liver , heart, and pancreas, as well as increase the risk of certain cancers.

Taking iron supplements that contain more than 20 mg of elemental iron at a time frequently can cause nausea , vomiting and stomach pain, particularly if the supplement is not taken with food. Overdoses of iron can lead to organ failure, internal bleeding, coma, seizure and even death in extreme cases.

To minimize the risk of fatal overdose, it’s crucial to keep iron supplements out of reach of children.

According to Poison Control, accidental ingestion of iron supplements was the most common cause of death from drug poisoning in children under the age of 6 until the 1990’s.

Changes in the manufacture and delivery of iron supplements have helped to minimize unintentional iron overdoses in children, such as replacing sugar coatings with film coatings on iron tablets, using childproof bottle caps and individually labeling large doses of iron. In the period 1998 to 2002, only one death from an iron overdose was recorded.

Some studies have indicated an excessive intake of iron may increase the risk of liver cancer. Some evidence suggests high levels of iron can raise the risk of type 2 diabetes.

More recently, scientists have started to examine the potential role of excess iron in neurological disease development and progression, such as Alzheimer’s disease, and Parkinson’s disease. Iron can also play a directly damaging role in brain damage caused by bleeding within the brain. Mice work has shown that high iron statuses increase osteoarthritis risk.

Iron supplements can decrease the availability of many medications, including levodopa, used to treat restless leg syndrome, and Parkinson’s disease, and levothyroxine, used to treat low-function thyroid.

Proton pump inhibitors (PPIs) used for the treatment of reflux disease can minimize the amount of iron that the body can consume from both food and supplements.

Discuss with a physician or health care provider to take an iron supplement, because some of the symptoms of iron overload may mimic iron deficiency. Excess iron can be dangerous, and iron supplements are not recommended except in cases of diagnosed deficiency or when an person is at high risk of developing iron deficiency.

Rather than supplements, it is preferred to achieve optimum iron intake and status by diet. This can help to reduce the risk of iron deficiency and ensure good intake of the other nutrients contained in food along with iron.