Iron is an essential mineral.

However, like many other nutrients, it is harmful in high amounts.

In fact, iron is so toxic that its absorption from the digestive tract is tightly controlled.

For the most part, this minimizes the harmful effects of excess iron.

It is when these safety mechanisms fail that health issues arise.

This article discusses the potentially harmful effects of consuming too much iron.

Iron is an essential dietary mineral, mostly used by red blood cells.

It is a crucial part of hemoglobin, a protein found in red blood cells. Hemoglobin is responsible for delivering oxygen to all of the body's cells.

There are two types of dietary iron:

  • Heme iron: This type of iron is only found in animal foods, mostly in red meat. It is absorbed more easily than non-heme iron.
  • Non-heme iron: Most dietary iron is in the non-heme form. It is found in both animals and plants. Its absorption can be enhanced with organic acids, such as vitamin C, but is decreased by plant compounds like phytate.

People who get little or no heme iron in their diet are at an increased risk of iron deficiency (1, 2).

Many people are iron deficient, especially women. In fact, iron deficiency is the world's most common mineral deficiency (3).

Bottom Line: Iron is an essential dietary mineral that plays an important role in transporting oxygen throughout the body. Iron deficiency is common among women.




Hepcidin, the body's iron-regulatory hormone, is responsible for keeping iron stores in balance. Its main function is to suppress the absorption of iron.

Basically, this is how it works (4):





Bottom Line: The rate of iron absorption from the digestive tract is tightly regulated by the hormone hepcidin. However, several iron overload disorders may disrupt this fragile balance.

Iron toxicity can be either sudden or gradual.




However, iron toxicity can significantly increase the levels of "free" iron in the body.

Free iron is a pro-oxidant - the opposite of an antioxidant - and may cause damage to cells.

Several conditions may cause this to happen. These include:

  • Iron poisoning: Poisoning can occur when people, usually children, overdose on iron supplements (5, 6).







Iron overload refers to the gradual build up of too much iron in the body. It is caused by the body's regulatory system failing to keep iron levels within healthy limits.


The most common iron overload disorder is hereditary hemochromatosis. This leads to the build up of iron in tissues and organs (7, 10).





  • Donating blood regularly.
  • Avoid using iron cookware.



There is no doubt that iron overload may lead to cancer in both animals and humans (12, 13).


Observational studies suggest that a high intake of heme iron may increase the risk of colon cancer (15, 16).

Clinical trials in humans have shown that heme iron from supplements or red meat may increase the formation of cancer-causing N-nitroso compounds in the digestive tract (17, 18).


Bottom Line: Iron overload disorders have been linked with an increased risk of cancer. Studies also suggest that heme-iron may raise the risk of colon cancer.

Both iron overload and iron deficiency appear to make people more susceptible to infection (19, 20).

There are two reasons for this (21):


Several studies indicate that iron supplementation may increase the frequency and severity of infections, although a few studies found no effects (22, 23, 24, 25, 26, 27).



Bottom Line: Iron overload and high-dose iron supplementation may increase the risk of infection in certain individuals.

In short, iron can be dangerous in high quantities.



Never take iron supplements unless recommended by your doctor.