Fundamentals of Human Nutrition/Iron

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11.1 Iron[edit]

Iron is a mineral found in every cell of the body and does many things in our bodies. Iron is an integral part of many proteins and enzymes that maintain good health. In humans, iron is an essential component of proteins involved in oxygen transport. For example, iron (as part of the protein hemoglobin) carries oxygen from our lungs throughout our bodies. It is also essential for the regulation of cell growth and differentiation. Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. Iron is also found in proteins that store iron for future needs and that transport iron in blood. Iron stores are regulated by intestinal iron absorption.

11.1.1 Sources[edit]

Iron can be found in a wide range of food sources. There are two types of dietary iron sources, heme iron and nonheme iron. Heme iron is derived from hemoglobin, which makes up 40% of iron found in animal sources [1]. Heme iron is well absorbed. Examples of adequate animal source foods are red meats, fish, poultry, shellfish, and eggs. Liver, oysters, chickpeas, pumpkin seeds, soybeans and fortified cereals are especially bulky sources of dietary iron. Nonheme iron is derived from plant sources, making up 60% of iron found in plants and some animal tissues, such as in legumes, lentils, beans, spinach and dried fruits [2]. Our bodies less efficiently absorb nonheme iron but it makes up the majority of our dietary iron. George Mateljan says that plant source foods contain more than 10% of our daily iron requirement per serving [3]. This can be explained by the fact that plant source foods have fewer calories per serving and therefore have a higher density of nutrients per calorie. To assist our bodies in absorption of iron it is beneficial to eat an iron source along with a source of vitamin C. Adding 50 milligrams or more of vitamin to an iron-rich meal will make it possible to triple the absorption of dietary iron [4]. According to nutritionist, vitamin C has a stronger affect on nonheme iron than it does on heme iron. Many vegetables such as broccoli are high in both iron and vitamin C, thus allowing a hefty amount of iron to be absorbed. Certain foods and beverages can decrease iron absorption, for example tea and coffee.

11.1.2 Functions[edit]

Iron is an essential nutrient because it is required to make hemoglobin and myoglobin, which are oxygen-carrying proteins in the body’s blood cells [5]. Hemoglobin is located in red blood cells, while myoglobin is located in muscles. About 70% of the bodies iron is found in hemoglobin and myoglobin [6]. Hemoglobin assist in the transfer of oxygen from the lungs to tissues located throughout the body. Iron is what creates the red color to our blood. Myoglobin receives, supplies, carries, and releases oxygen to our body muscles and the heart. Another function of iron is to make other body proteins, such as proteins essential for respiration and energy metabolism. Iron is also a component of enzymes that are involved in the synthesis of DNA, collagen, and certain neurotransmitters. Finally, iron contributes to proper immune function [7]. This function of iron is most important during childhood and pregnancy.

11.1.3 Requirements[edit]

11.1.4 Imbalance[edit]

  1. Mangels, R. (2013, February 5). Iron in the Vegan Diet. Retrieved August 3, 2015, from http://www.vrg.org/nutrition/iron.php
  2. Mangels, R. (2013, February 5). Iron in the Vegan Diet. Retrieved August 3, 2015, from http://www.vrg.org/nutrition/iron.php
  3. Mateljan, G. (2001). Iron. Retrieved August 3, 2015, from http://www.whfoods.com/genpage.php?tname=nutrient&dbid=70
  4. Mateljan, G. (2001). Iron. Retrieved August 3, 2015, from http://www.whfoods.com/genpage.php?tname=nutrient&dbid=70
  5. Evert, A. (2013, February 18). Iron in Diet. Retrieved August 3, 2015, from http://www.nytimes.com/health/guides/nutrition/iron-in-diet/overview.html
  6. UCSF Medical Center. (2002). Hemoglobin and Functions of Iron. Retrieved August 3, 2015, from http://www.ucsfhealth.org/education/hemoglobin_and_functions_of_iron/
  7. Spatone. (2014). Role of Iron in the Body. Retrieved August 3, 2015, from http://www.nelsonsnaturalworld.com/en-GB/uk/our-brands/spatone/iron-essentials/role-of-iron-in-the-body