Last Updated: October 3, 2022

Iron is an essential mineral best known for allowing blood to carry oxygen between tissues. Except in case of deficiency, iron supplementation has no proven benefit; on the contrary, it can lead to iron poisoning.

Iron is most often used for


What is iron?

Iron is an essential dietary mineral present in a wide variety of foods. In its main role in the body, iron is a critical component of hemoglobin — the oxygen carrier of red blood cells — and a deficiency in iron leads to poor oxygen transport (anemia). In addition, iron acts as a cofactor for many enzymes. The iron found in plants (notably grains and legumes) is less bioavailable than the iron found in meat (in the form of heme). Iron is the double-edged sword of the nutrient world. On the one hand, many people have insufficient levels, but on the other hand, iron overload can be toxic to a wide variety of cells. Iron deficiency is the only reason to consider iron supplementation, though getting more iron through foods is preferable when possible. For people who already have enough iron, taking an iron supplement has no proven benefit, and on the contrary, it can lead to iron overdose.

What are the benefits of iron?

A lack of iron tends to produce fatigue, depression, impaired cognitive function, restless leg syndrome, and other adverse effects. Correction of an iron deficiency tends to improve symptoms, and even among people who aren't anemic, more than the bare minimum amount of iron may be needed to produce the optimal amounts of hemoglobin and reap the benefits of greater oxygen delivery; however, the beneficial effect is probably limited to people whose iron levels are low according to conventional standards, though more research is needed. Iron supplements are also often used by athletes in an attempt to improve physical performance, however once again there does not appear to be any benefit when iron levels are not low. Iron deficiency is fairly common, and a great number of factors negatively affect iron status, so iron supplementation and iron-rich diets can be expected to benefit many people.

What are the downsides of iron?

Supplementation can produce nausea, headaches, and other symptoms. As previously mentioned, iron overload is a serious health risk.

Dosage information

Make sure that you get the recommended daily allowance (RDA) for your gender, age, and situation:

  • 8 mg for men and nonmenstruating women
  • 15 mg for menstruating women 14–18 years old
  • 18 mg for menstruating women 19–50 years old
  • 27 mg for pregnant women
  • 10 mg for lactating women less than 18 years old
  • 9 mg for lactating women, 19–50 years old

Those numbers include the iron in your diet. Getting enough iron from foods makes supplementation unnecessary. Be careful not to ingest more iron than the daily tolerable upper intake level (UL) for your age, e.g., 45 mg for people older than 13.

For more details, see the Recommended Intake section below.

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