Iron is an essential nutrient the human body needs to make oxygen-carrying proteins found in red blood cells. Although iron deficiencies can cause health problems, iron consumed in excess can be toxic or even fatal. Iron toxicity caused by consuming dietary iron from foods is unlikely; however taking iron supplements in excess can cause problems.
Basics
Multivitamins, prenatal vitamins and iron supplements are sources of iron that can cause harmful iron toxicity. Taking iron supplements in large doses may be required for people who are anemic, meaning the iron stores in their bodies have been depleted. However, overload can occur when iron stores are full, and iron starts to accumulate in organs or other body tissues, notes the National Institutes of Health Office of Dietary Supplements.
Causes
Taking large doses of iron supplements and certain medical conditions are common causes of iron toxicity. Small children who get hold of iron supplements are at risk for overdosing on iron, which can be fatal. All iron-containing products should be kept out of a child's reach. Medical conditions, such as hemochromatosis, also can cause iron toxicity. With hemochromatosis, a genetic disease, the body absorbs too much iron, which can lead to organ damage and other diseases, according to the National Human Genome Research Institute.
Symptoms
Acute symptoms from taking high doses of iron supplements include nausea, vomiting, constipation or diarrhea. Long-term effects from iron overload include iron accumulation in body organs and diseases such as heart disease, joint disease, liver cancer, cirrhosis of the liver or diabetes, notes the National Human Genome Research Institute.
Recommendations
The recommended dietary allowance, or RDA, for iron in adults is 8 mg for men, 18 mg for women under age 51, 8 mg for women over 50 years, 27 mg for pregnant women and 9 mg for lactating women. The tolerable upper intake for iron--or the amount of iron that should not be exceeded unless iron deficiency is present--is 45 mg for all adults, according to the Office of Dietary Supplements.
Concerns
Individuals with hemochromatosis, adult men, menopausal women and children have lower iron requirements, are at an increased risk for iron toxicity from supplementation and should use caution when taking iron supplements. Consult a health-care professional before taking any iron-containing supplements.
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