Iron is a component of a number of protein such as hemoglobin, myoglobin and enzymes. Two thirds of the iron in the body is found in hemoglobin in circulating red blood cells. Hemoglobin is important to transport the oxygen around the body. Iron requirements change during periods of rapid growth (childhood, adolescents), menstruating women and pregnancy.
Not all dietary iron is equally available to the body. Iron in foods can come in two different forms: haem and non-haem iron. Iron from animal food sources such as meat, fish and poultry may be either haem or non-haem whereas the iron in plant sources such grains and vegetables is non-haem. The haem form is more bioavailable to humans than the nonhaem.
The presence of other nutrients may influence the rate of absorption of iron. Vitamin C increase the absorption of non-haem iron, consumption of haem iron from meat, fish or poultry can also increase absorption of non-haem iron. In contrast, some other nutrients such as Calcium, Zinc and phytates (found in legumes and wholegrains) can inhibit the absorption of both haem and non-haem iron.