Iron
Overview
Iron is an extremely important mineral that is used throughout the body and in turn affects how the entire body functions. The main role of iron is as part of the hemoglobin contained in red blood cells; these cells are responsible for carrying oxygen to tissues throughout the body. Iron is also found in myoglobin, which supplies oxygen to the muscles, including the heart. A lack of sufficient iron results in inadequate oxygen distribution throughout the body; this condition causes weakness, fatigue, decreased stamina for physical activity, and, when prolonged, may lead to anemia. Iron deficiency is a rather significant problem, especially for adolescents, women of childbearing age, pregnant and breastfeeding women, and the elderly.
Sources of Iron
There are two different forms of dietary iron. Heme iron is found in animal products; it is already bound to hemoglobin and myoglobin, and so is more easily absorbed by the body. Nonheme iron is not as absorbable as heme iron, and it is found in plant sources. Consuming foods that contain heme iron and nonheme iron at the same time helps improve the body’s absorption of the nonheme iron. Vitamin C and food containing protein aid iron absorption as well, especially when the iron comes from non-animal food sources. Certain minerals such as copper and manganese also help improve the body’s ability to absorb iron.
Since iron from animal sources is more easily absorbed, foods like meat, poultry, and fish, including salmon and shellfish, are great sources of iron. Other sources of iron include green leafy vegetables like chard and kale; dried fruit, including prunes and raisins; and nuts such as Brazil nuts and almonds. Preparing foods in cast iron cookware can also increase the iron content of the foods.
Iron supplements are available and are crucial to the maintenance of many individuals’ healthy iron levels. Supplements include iron glycinate, iron fumarate, iron gluconate, and iron sulfate. Iron sulfate, while used often to supplement iron intake, has the tendency to cause some digestive irritation.
Functions of Iron
Iron plays a crucial role in the delivery of oxygen throughout the body. Iron is part of hemoglobin, a protein-iron compound that is formed in bone marrow and exists in red blood cells. The job of hemoglobin is to carry oxygen throughout the body; the hemoglobin takes oxygen from the lungs, brings it around to tissues throughout the body, picks up carbon dioxide from the tissues, and transports it back to the lungs for release. Myoglobin is another iron-protein compound that stores oxygen in muscle tissue and acts as an oxygen reserve in the muscles. Myoglobin affects the body’s ability to perform physically by increasing the amount of oxygen that flows to muscles that are engaged in some sort of activity.
Iron, and its role in transporting oxygen throughout the body, is crucial to the functioning of the body; without enough oxygen, tissues and muscles are less able to perform. In turn, iron plays a significant role in the body’s ability to perform physical tasks and maintain stamina.
Uses of Iron
Iron is primarily used to prevent and treat iron deficiency. Iron supplements are used often during pregnancy and breastfeeding, as women who are pregnant or breastfeeding are at high risk of iron deficiency. Iron supplements may also be used to treat fatigue, particularly muscle fatigue; an increase in iron may help increase the amount of oxygen that circulates throughout the body, thus decreasing fatigue.
Iron Deficiency
Iron deficiency is a rather significant problem, particularly among women. Although the body regulates the rate of iron absorption, absorbing more or less iron as the body’s needs require, a person’s iron intake may be insufficient to meet their iron needs. Iron deficiency occurs for many reasons including insufficient dietary intake, a decrease in the amount of iron that is absorbed or used in the body, and blood loss. People who adhere to vegetarian diets are often at higher risk of iron deficiency because they lack a significant dietary source of iron: meat and other animal food sources, which contain the most absorbable forms of iron. Also, due to potentially heavy menstrual bleeding, women of childbearing age are at higher risk of iron deficiency as well. Insufficient absorption of iron can also lead to iron deficiency; this cause of iron deficiency is common in elderly people whose stomachs may lack the hydrochloric acid needed to help absorb iron. Also, certain whole grains, vegetables, and medications, such as aspirin, tetracycline, and allopurinol, may impede the body’s ability to absorb iron, which may lead to iron deficiency.
The risk of iron deficiency increases during periods of growth when the amount of iron needed in the body increases; in turn, infants, adolescents, and pregnant women have a more significant risk of iron deficiency because their bodies are growing and therefore require more iron to maintain healthy levels of the mineral. In the later months of pregnancy, women pass about seven to eight milligrams of iron each day to their babies, which, unless taking an iron supplement, puts them at risk of iron depletion.
When there is not enough iron in the body, oxygen does not travel to the tissues throughout the body as it should. Side effects that accompany low iron levels include weakness, fatigue, decreased stamina for physical activity, learning difficulties, and irritability, among other things. The immune system also suffers during periods of iron deficiency which may lead to an increased risk of infection.
Although anemia can be brought on by other factors such as Vitamin B6 and zinc deficiencies, iron deficiency is a significant cause of anemia. Anemia is a condition in which a person’s red blood cell count is low, and therefore there is not enough oxygen being delivered to tissues throughout the body. Anemia is actually the last stage of iron deficiency, and is characterized by fatigue, reduced physical endurance, paleness, apathy, and depression, among other things. Prolonged iron deficiency eventually results in anemia; however, a person can have low levels of iron before actually becoming anemic.
Iron toxicity is much less common than iron deficiency. Hemochromatosis is a condition in which, from birth, the body absorbs more iron than it needs, and so an excess of iron within the body results and can cause damage to organs. Also, exposure to smoke can increase the risk of an iron surplus. Iron toxicity may result in weight loss, joint pain, impotence, premature menopause; high levels of iron may also contribute to heart disease and Alzheimer’s and Parkinson’s diseases.
Required Daily Amount
The body regulates the rate of iron absorption to a certain degree, absorbing more or less iron depending on the body’s needs. In general, women require higher iron intakes than men; while men typically have about 1,000 milligrams of iron in their bodies, menstruating women have only about 200 to 400 milligrams. The recommended daily intake for men is 15 to 25 milligrams, while for women it is 18 to 30 milligrams. Also, women who are pregnant and breastfeeding have a more difficult time maintaining healthy levels of iron and therefore require more iron.
References
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- Brewer, S. The essential guide to vitamins, minerals and herbal supplements, Right Way (2010)
- Elson M. Haas, Md & Buck Levin, Phd, Rd. Staying Healthy with Nutrition: The Complete Guide to diet and nutritional medicine, Celestial Arts (2006)
- Holford, P. The optimum nutrition bible, Little Brown Group (2004)
- Holford, P & Lawson, S. Optimum Nutrition Made Easy How to achieve optimum health, Piatkus Books (2008)
- Lieberman, S. & Bruning, N. The Real Vitamin & Mineral Book, Avery, a Member of Penguin Group (USA) Inc (2003)
- Rodale Health Books. Healing with vitamins : the best nutrients to slow, stop, and reverse disease, Rodale, (2009)
- Royston, A. Vitamins and minerals for a healthy body, Heinemann Library, (2003)
- The National Research Council. Recommended Dietary Allowances, 10th ed, National Academy of Sciences (1989)
- Werbach, M. Nutritional Influences on Illness, 2nd ed, Third Line Press (1993)
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