Iron

Trace mineral · oxygen carrier

What does Iron do in your body?

The atom at the center of hemoglobin that lets red blood cells carry oxygen.

How it works, step by step

1. Non-heme iron is converted to a soluble form in the gut (helped by vitamin C).
2. Gut cells absorb only what the body signals it needs (via hepcidin).
3. Transferrin carries iron in blood to bone marrow.
4. Marrow builds it into hemoglobin in new red cells.

What does Iron do?

Binds oxygen in hemoglobin (blood) and myoglobin (muscle); part of enzymes that make energy.

Where does Iron act in the body?

Red blood cells, muscle, liver (storage), bone marrow.

Which foods contain Iron?

Heme iron: red meat, poultry, fish. Non-heme: lentils, beans, spinach, tofu, fortified cereals.

How much Iron do adults need?

RDA: 8 mg (men; women 51+), 18 mg (women 19–50), 27 mg in pregnancy. Upper limit: 45 mg.

What happens with too little Iron?

The most common nutrient deficiency worldwide. Can lead to iron-deficiency anemia: tiredness, weakness, shortness of breath. Diagnosed with blood tests.

Can you get too much Iron?

The body can't actively excrete iron. Accidental iron supplement overdose can be fatal for young children, which is why packs carry a child-safety warning.

What does Iron interact with?

Vitamin C increases non-heme absorption; tea, coffee, calcium and phytates reduce it.

What is known and unknown about Iron?

Roles are established. Too much iron is harmful, and iron status can only be judged with blood tests, so supplement decisions belong with a clinician.

Evidence & sources

• RDA for iron is 8 mg/day for adult men and 18 mg/day for women aged 19–50. Evidence: regulatory. Known: Higher for menstruating women due to losses. Unknown: Individual needs vary; status requires lab testing. Source: NIH Office of Dietary Supplements, Iron — Health Professional Fact Sheet (Current revision).
• Iron deficiency is the most common nutritional deficiency worldwide. Evidence: strong. Known: Global surveillance data. Unknown: Prevalence varies widely by region. Source: World Health Organization, Anaemia — fact sheet (Current revision).

Connected topics

• Spinach
• Lentils
• Vitamin C
• Blood
• Small Intestine
• Lungs
• Heart

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.