Iron is a term used to describe two related nutrients you need to form your red blood cells, regulate normal cell growth and deliver oxygen to your body. If you don't get enough iron, you can develop a red blood cell disorder called anemia. Iron absorption in your gastrointestinal system varies according to a number of different factors.
Types of Dietary Iron
One form of iron, called heme iron, comes from a protein called hemoglobin, which transports oxygen inside the red blood cells of humans and other animals. To get this type of iron in your diet, you need to eat hemoglobin-containing animal foods such as poultry, fish and red meat. The second form of dietary iron, called nonheme iron, comes from beans, spinach, lentils, soybeans, raisins and other plant-based foods, as well as from artificially fortified foods like oatmeal and cereal. Since animals commonly eat plants, animal-based foods also contain nonheme iron.
Varying Absorption Percentages
Most of the iron in the average diet comes from nonheme sources, according to the National Institutes of Health's Office of Dietary Supplements. Your gastrointestinal system has a relatively hard time absorbing nonheme iron, however, and anywhere from 2 to 20 percent of this type of iron passes from food to your body during digestion. Conversely, your system has a relatively easy time absorbing iron from heme sources, and roughly 15 to 35 percent of this type of iron passes to your body during the digestion process.
Iron-Deficiency Anemia
If you don't absorb enough iron from your diet, your body will start drawing on its reserve supply of the mineral, which is stored inside molecules of a protein called ferritin. Once you deplete these reserves, your body will start decreasing its production of red blood cells. In addition, any red blood cells your body does produce will contain reduced levels of hemoglobin. Potential consequences of this condition, called iron-deficiency anemia, include chest pain, fatigue and shortness of breath. If you develop a severe case of this form of anemia, you can develop additional symptoms that include infections and heart function abnormalities. Children with severe iron-deficiency anemia can also experience disruptions in their normal growth and development.
Considerations
You can increase your body's ability to absorb nonheme iron by eating high-vitamin C foods at the same time as dietary iron, Colorado State University Extension reports. Foods rich in this vitamin include tomatoes, leafy greens, strawberries and citrus fruits and juices. You can also improve absorption by eating nonheme iron foods at the same time as heme-containing foods. Factors that can lower your gastrointestinal absorption of dietary iron include consumption of coffee or tea at mealtimes and consumption of low-nutrient foods such as potato chips, sugar-sweetened desserts and sugar-sweetened sodas. Other substances may also lower your iron absorption, including certain soybean proteins, the phosphate content in cola sodas, grain and legume constituents called phytates, fiber and calcium.
Consult your doctor for more information on anemia and the gastrointestinal factors affecting iron absorption.
References
- Office of Dietary Supplements - National Institutes of Health: Dietary Supplement Fact Sheet; Iron
- National Heart Lung and Blood Institute: What Is Iron-Deficiency Anemia?
- Colorado State University Extension: Iron; An Essential Nutrient; J. Anderson, C. Fitzgerald; June 2010
- Washington University in St. Louis: Iron Use and Storage in the Body...; Rachel Casiday, Regina Frey
Member Comments