There are 2 main types of dietary iron, heme iron and non-heme. Heme iron is more readily absorbed and sources include liver, meat, poultry and fish. Non-heme iron is less efficiently absorbed but absorption increases depending on the body’s needs. Non-heme iron sources include spinach, eggs, nuts, beans and fortified breads, cereals and flours. Importantly, phytates (found predominantly in cereals, oats, bran and whole wheat flour) and phenolic compounds (found in tea, cocoa, and many herbs) strongly inhibit iron absorption so care should be taken to assess dietary sources of iron as well as total quantity. Vitamin C can markedly increase iron absorption so vitamin C sufficiency should also be assessed.
Toxicity may occur if too much iron is absorbed, most commonly caused by a hereditary condition known as hemochromatosis. Iron is an essential trace element, which functions primarily as a carrier of oxygen in the blood (haemoglobin) and muscles (myoglobin). It also aids in immune function, cognitive development, temperature regulation, energy metabolism and work performance. Iron is recycled heavily by our body and dietary iron only replaces approximately 10% that is lost through skin cells, the interior surfaces of our body and from bleeding and menstruation.