How much iron do you need per day?

Under normal circumstances you lose roughly 1 to 2 mg of iron every day through your skin, the lining of your gut and sweat. You need to make up for that through food. You therefore do not necessarily need an exact 'recommended amount' of hundreds of milligrams; that 1 to 2 mg is what your body actually loses and needs to take in to stay in balance.

Iron occurs in two forms in food. Haem iron, from red meat and fish, is absorbed by your body relatively easily. Non-haem iron, from legumes, leafy vegetables and fortified bread or breakfast cereals, is absorbed less efficiently. Your gut first has to convert it into a different chemical form before it can be taken up. Vitamin C consumed during the same meal helps with that process.

Pregnant women and women who are breastfeeding have a considerably higher iron requirement than those 1 to 2 mg per day. Exactly how much higher depends on the stage of pregnancy and whether the baby is being fed through breastfeeding. If you are pregnant or planning to become pregnant, it is wise to discuss this with your doctor or midwife.

If you have an iron deficiency or iron-deficiency anaemia, the amounts involved are in an entirely different order of magnitude. Treatment sometimes involves giving up to 200 mg of elemental iron per day as a supplement, for a period of three to twelve weeks. That sounds like a lot, but your body absorbs only a small fraction of it. Such doses are never used casually as a preventive measure; they are intended to correct a demonstrated deficiency under the supervision of a healthcare provider.

It is true that iron also plays a role in the immune system, but the strongest evidence for immune support through supplements applies to vitamin C, vitamin D and zinc. Using iron on its own to influence your immune system is currently much less well supported by evidence.