Iron
A mineral essential for oxygen transport (via haemoglobin) and energy production, whose deficiency is the leading cause of anaemia worldwide.
Iron occurs in two dietary forms:
- Haem iron (meat, fish): absorption about 15 to 25%
- Non-haem iron (plants, eggs): absorption about 2 to 5%
An original angle (absorption modulators): absorption of non-haem iron is extremely context-dependent. It is:
- Multiplied by vitamin C (orange juice with lentils), meat (the “meat factor”), acidity
- Divided by tannins (tea, coffee), calcium (dairy products), phytic acid (unsoaked wholegrain cereals)
Hence the little-known practical tip: avoid tea and coffee with iron-rich meals, and add a source of vitamin C.
The iron paradox: it is both essential and toxic. The body has no mechanism for actively excreting excess iron. An excess (genetic haemochromatosis, over-supplementation) is pro-oxidant and damages the liver, heart and pancreas. That is why you should never take iron supplements without a blood test (ferritin).
Groups at risk of deficiency: women who menstruate, pregnant women, vegans, endurance athletes (the haemolysis of exertion destroys red blood cells), regular blood donors.
Ferritin (iron stores) is a better indicator than haemoglobin: you can have normal haemoglobin but depleted stores (“deficiency without anaemia”), causing fatigue and breathlessness.