Iron is the most abundant trace element present in the human body.

Important sources of iron are pig liver, leguminous plants, oats, and calf meat. The percentage of iron is not the only important factor. Other constituents in a meal, which influence how well iron is absorbed, are equally important. The availability of iron in animal foods is appreciably higher than in plant foods.

Phytic acid (e.g. in bran components in cereals), oxalic acid (e.g. in spinach or rhubarb), tannin, calcium, phosphate, as well as some dietary fibres inhibit the absorption of iron. Vitamin C and lactic acid (in whey, yoghurt, and sauerkraut) promote iron’s absorption.

Good sources of iron are meat, wheat germs, oatmeal, wholemeal bread, spinach, millet, quinoa, and amaranth. Quinoa, and amaranth are plants that were cultivated by the Incas and Aztecs. In the past, spinach was heavily promoted as a good source of iron. This was, however, the result of an analysis error.

Iron is present in haemoglobins and myoglobins. It is necessary for the transportation of oxygen and for the production of energy in cells. It also takes on other functions in the immune system and DNS synthesis.