Heme vs Nonheme Iron
There are many minerals found in the body. Among them, iron is the most recognizable mineral found in the animal body. Even though the amount of iron in an adult is a little less than a teaspoon, iron deficiency could be tragic and severe in many animals. Iron is a very essential mineral for optimal brain and nervous system development and function. In humans as well as in other animals, iron is associated with the molecule called ‘heme’. Heme is a part of a larger protein complexes (hemoglobin and myoglobin), and it is found only in the animals. Plants do not have heme and hence the presence of heme makes animals different from plants. Normally, total body iron averages about 4g in men and a little more than 2g in women. In the human body, iron (heme-iron) is mainly associated with hemoglobin and myoglobin proteins. Iron is also found in enzymes, and if the body is well-nourished with iron, it will have good iron reserves stored as ferritin and hemosiderin. However, too much iron inevitably results in toxic conditions, in the body.
Heme iron is derived from hemoglobin and myoglobin so it is found only in animal tissue. These irons are more bioavailable and are found in meat, fish, poultry, and sea foods. Heme iron is mainly found as the ferrous iron (Fe II), in the form of reduced iron, associated with hemoglobin and myoglobin.
Non-heme iron is found in both animal and plant food products, even though it is not easily absorbed by the body. Dietary non-heme iron is present in the oxidized form of iron or ferric iron (Fe III). It has to be reduced to ferrous iron (Fe II) in order to be taken by the duodenal entrocytes. The reduction is mainly done by a ferric reductase enzyme (Cytochrom b reductase).
The bioavailability of non-heme iron can be improved by taking vitamin C rich foods like fruits and vegetables along with iron containing foods. Also by having heme iron rich foods (animal products) along with the foods that are rich in non-heme iron, can improve the absorption of non-heme iron. Certain chemicals like polyphenols which are found in tea, coffee, other beverages, and many plants, limit the absorption of non-heme iron.
What is the differences between heme iron and nonheme iron?
• Heme iron is much more bioavailable than non-heme iron so that heme iron is better absorbed than non heme iron.
• Heme iron is found only in animal foods while non-heme iron is found in both animal and plant foods.
• Plant foods contain only non-heme iron. Heme irons are absent in the plant foods.
• Foods rich in heme-iron can improve the absorption of non-heme iron.
• The most abundant dietary iron is non-heme iron. Normally, 60% of non-heme iron is present in animal products. The remaining 40% is heme iron.
• Dietary non-heme iron is present as ferric iron (Fe III), and it has to be reduced to ferrous iron (Fe II) in order to be absorbed.
• Unlike non-heme iron, heme iron is associated with hemoglobin and myoglobin in the form of ferrous (Fe II) iron.