Iron

Iron is an essential component of haemoglobin, transporting oxygen in the blood to all parts of the body. Iron also plays a vital role in many metabolic reactions. Iron deficiency can cause anaemia resulting from low levels of haemoglobin in the blood. Iron deficiency is the most widespread mineral nutritional deficiency both in Britain and worldwide.
The body contains between 3.5 and 4.5g of iron, 2/3 of which is present in haemoglobin. The remainder is stored in the liver, spleen and bone-marrow. A small amount is present as myoglobin, which acts as an oxygen store in muscle tissue.
In anaemia, iron stores in the body become depleted and haemoglobin synthesis is inhibited. Symptoms include tiredness, lack of stamina, breathlessness, headaches, insomnia, loss of appetite and pallor. Iron also plays an important role in the immune system, people with low iron levels having lowered resistance to infection. Iron deficiency is associated with impaired brain function, and iron deficiency in infants can result in impaired learning ability and behavioural problems.
2/3 of children and women of child-bearing age in developing countries suffer from iron deficiency, 1/3 suffering from severe deficiency and anaemia. In developed countries, between 10-20% of child-bearing age women are said to be anaemic. However, it is unusual for a man in the developed world to be anaemic unless he either suffers from internal bleeding or has an extremely poor diet.
Dietary iron exists in two different forms. Haem iron only exists in animal tissues, whilst in plant foods iron is present as non-haem iron. In a mixed omnivore diet around 25% of dietary iron is non-haem iron. Non-haem iron is less easily absorbed by the body than is haem iron. Phytates, oxalates and phosphates present in plant foods can inhibit absorption of iron, as can tannin in tea, or fibre. Vitamin C greatly increases the absorption of non-haem iron. Foods rich in vitamin C include citrus fruits, green peppers, and fresh leafy green vegetables. Citric acid, sugars, amino acids and alcohol can also promote iron absorption.
Iron absorption can also be influenced by the amount of iron in the diet. Lowered levels of iron in the diet result in improved absorption.
Good sources of iron for vegetarians include wholegrain cereals and flours, leafy green vegetables, blackstrap molasses, pulses such as lentils and kidney beans, and some dried fruits.
In women of child-bearing age, loss of iron from menstruation adds considerably to iron need. These losses can be highly variable. Around 10% of women of child-bearing age will need more iron than is indicated by the RDA (approximately 15mg for women of child-bearing age).
In men, post-menopausal women, and children iron is efficiently conserved by the body. Iron in haemoglobin is recycled and the amount of iron lost from the body is very small. Infants and children need extra iron to increase blood volume and muscle tissue. Extra iron is also required during pregnancy and breast feeding, or after severe injury or surgical operations involving blood loss.