Iron
Iron is an essential mineral used in hemoglobin and myoglobin and is therefore central to oxygen transport and use. Iron status should be assessed rather than inferred from symptoms alone because both too little and too much iron can be harmful.
What it does in the body
- Required for hemoglobin and oxygen transport
- Required for myoglobin and muscle oxygen use
- Participates in many enzymes and cellular processes
Daily reference intake
In the U.S. DRI system, adult men and adults over 51 generally need 8 mg/day; women aged 19–50 need 18 mg/day; pregnancy increases the requirement to 27 mg/day.
What can deficiency look like?
- Fatigue, weakness and reduced exercise tolerance
- Iron-deficiency anemia
- Pale skin or shortness of breath may occur as anemia becomes more pronounced
- Symptoms are not specific and need laboratory confirmation
Who may be at higher risk?
- Pregnant women
- Infants and young children
- Women with heavy menstrual bleeding
- Frequent blood donors
- People with gastrointestinal disorders or other causes of blood loss
Food sources
A varied diet is the first place to look for nutrients. Availability and nutrient content can vary by food, preparation and country.
Food-source note: Heme iron from animal foods is generally absorbed more efficiently than non-heme iron from plant foods. Vitamin C can improve absorption of non-heme iron.
Absorption & practical context
Iron absorption is tightly regulated. Heme and non-heme iron are absorbed differently, and factors such as vitamin C, phytates and existing iron stores influence non-heme iron absorption.
How status is assessed
Ferritin is commonly used to assess iron stores, usually together with a complete blood count and other iron markers. Inflammation can raise ferritin, so interpretation requires context.
Important interactions
- Iron can reduce absorption of levothyroxine and some antibiotics if taken too close together
- Calcium and some food components can reduce iron absorption
Safety and context
Excess iron can cause gastrointestinal symptoms and, at high doses, serious toxicity. Iron supplements should not be used simply because a person feels tired; suspected deficiency should be confirmed and the cause evaluated.
Scientific sources
NIH Office of Dietary Supplements — Iron ↗ EU Register of Nutrition and Health Claims ↗Products whose current label lists this nutrient
The entries below are based on current manufacturer label information for the selected market. Compare the stated amount per daily serving and read the official product page before purchasing.