{"id":222,"date":"2020-01-03T21:36:47","date_gmt":"2020-01-03T21:36:47","guid":{"rendered":"http:\/\/opentextbooks.concordia.ca\/fundamentalsofhealthandphysicalactivity\/?post_type=chapter&p=222"},"modified":"2021-07-21T12:49:41","modified_gmt":"2021-07-21T12:49:41","slug":"1-10-3-trace-minerals","status":"publish","type":"chapter","link":"https:\/\/opentextbooks.concordia.ca\/fundamentalsofhealthandphysicalactivity\/chapter\/1-10-3-trace-minerals\/","title":{"raw":"1.3.12. More About Trace Minerals","rendered":"1.3.12. More About Trace Minerals"},"content":{"raw":"

Introduction<\/h1>\r\nTrace minerals are classified as minerals required in the diet each day in smaller amounts, specifically 100 milligrams or less. \u00a0These include copper, zinc, selenium, iodine, chromium, fluoride, manganese, molybdenum, and others. \u00a0Although trace minerals are needed in smaller amounts it is important to remember that a deficiency in a trace mineral can be just as detrimental to your health as a major mineral deficiency. Iodine deficiency is a major concern in countries around the world.\r\n\r\n \r\n\r\n
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Figure 1.3.12.1<\/b> The Trace Minerals<\/em><\/p>\r\n\r\n

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<\/b> Minerals can be divided into major and minor classifications. Source: image by Allison Calabrese \/ CC BY 4.0<\/a>.<\/figcaption><\/figure>\r\n

Iron<\/h1>\r\nRed blood cells contain the oxygen-carrier protein hemoglobin. It is composed of four globular peptides, each containing a heme complex. In the center of each heme, lies iron (Figure 1.3.12.2 \"The Structure of Hemoglobin\"). Iron is needed for the production of other iron-containing proteins such as myoglobin<\/b>. \u00a0Myoglobin is a protein found in the muscle tissues that enhances the amount of available oxygen for muscle contraction. Iron is also a key component of hundreds of metabolic enzymes<\/b>. Many of the proteins of the electron-transport chain contain iron\u2013sulfur clusters involved in the transfer of high-energy electrons and ultimately ATP synthesis<\/b>. Iron is also involved in numerous metabolic reactions that take place mainly in the liver and detoxify harmful substances. Moreover, iron is required for DNA synthesis<\/b>. The great majority of iron used in the body is that recycled from the continuous breakdown of red blood cells.\r\n

Figure 1.3.12.2<\/b> The Structure of Hemoglobin<\/em><\/p>\r\n\r\n\r\n[caption id=\"attachment_711\" align=\"alignnone\" width=\"664\"]\"Diagram <\/b> Hemoglobin is composed of four peptides. Each contains a heme group with iron in the center. Source: Iron<\/a>.\u00a0[\/caption]\r\n\r\nThe iron in hemoglobin binds to oxygen in the capillaries of the lungs and transports it to cells where the oxygen is released. If iron level is low hemoglobin is not synthesized in sufficient amounts and the oxygen-carrying capacity of red blood cells is reduced, resulting in anemia<\/b>. When iron levels are low in the diet the small intestine more efficiently absorbs iron in an attempt to compensate for the low dietary intake, but this process cannot make up for the excessive loss of iron that occurs with chronic blood loss or low intake. When blood cells are decommissioned for use, the body recycles the iron back to the bone marrow where red blood cells are made. The body stores some iron in the bone marrow, liver, spleen, and skeletal muscle. A relatively small amount of iron is excreted when cells lining the small intestine and skin cells die and in blood loss, such as during menstrual bleeding. The lost iron must be replaced from dietary sources.\r\n\r\nThe bioavailability of iron is highly dependent on dietary sources.<\/b> In animal-based foods about 60 percent of iron is bound to hemoglobin, and heme iron is more bioavailable than nonheme iron<\/b>. The other 40 percent of iron in animal-based foods is nonheme, which is the only iron source in plant-based foods. Some plants contain chemicals (such as phytate, oxalates, tannins, and polyphenols) that inhibit iron absorption. Although, eating fruits and vegetables rich in vitamin C at the same time as iron-containing foods markedly increases iron absorption<\/b>. A review in the American Journal of Clinical Nutrition reports that in developed countries iron bioavailability from mixed diets ranges between 14 and 18 percent, and that from vegetarian diets ranges between 5 and 12 percent.[footnote]Centers for Disease Control and Prevention. \u201cIron and Iron Deficiency.\u201d Accessed October 2, 2011. http:\/\/www.cdc.gov\/nutrition\/everyone\/basics\/vitamins\/iron.html.[\/footnote] Vegans are at higher risk for iron deficiency, but careful meal planning does prevent its development. Iron deficiency is the most common of all micronutrient deficiencies.<\/b>\r\n

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Table 1.3.12.1<\/b> Enhancers and Inhibitors of Iron Absorption <\/em><\/p>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Enhancer<\/strong><\/td>\r\nInhibitor<\/strong><\/td>\r\n<\/tr>\r\n
Meat<\/td>\r\nPhosphate<\/td>\r\n<\/tr>\r\n
Fish<\/td>\r\nCalcium<\/td>\r\n<\/tr>\r\n
Poultry<\/td>\r\nTea<\/td>\r\n<\/tr>\r\n
Seafood<\/td>\r\nCoffee<\/td>\r\n<\/tr>\r\n
Stomach acid<\/td>\r\nColas<\/td>\r\n<\/tr>\r\n
<\/td>\r\nSoy protein<\/td>\r\n<\/tr>\r\n
<\/td>\r\nHigh doses of minerals (antacids)<\/td>\r\n<\/tr>\r\n
<\/td>\r\nBran\/fiber<\/td>\r\n<\/tr>\r\n
<\/td>\r\nPhytates<\/td>\r\n<\/tr>\r\n
<\/td>\r\nOxalates<\/td>\r\n<\/tr>\r\n
<\/td>\r\nPolyphenols<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\nSource: Iron<\/a>.\r\n

Figure 1.3.12.3<\/b> Iron Absorption, Functions, and Loss<\/em><\/p>\r\n\r\n

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<\/b> Iron absorption occurs in the intestine and is stored in the liver. Source: image by Allison Calabrese \/ CC BY 4.0<\/a>.<\/figcaption><\/figure>\r\n

Iron Toxicity<\/h2>\r\nThe body excretes little iron and therefore the potential for accumulation in tissues and organs is considerable. Iron accumulation in certain tissues and organs can cause a host of health problems in children and adults including extreme fatigue, arthritis, joint pain, and severe liver and heart toxicity. In children, death has occurred from ingesting as little as 200 mg of iron and therefore it is critical to keep iron supplements out of children\u2019s reach. Health Canada has set tolerable upper intake levels of iron at 40 for those under 14 years and 45 mg\/day for those over the age of 14 years.\u00a0Mostly a hereditary disease, hemochromatosis is the result of a genetic mutation that leads to abnormal iron metabolism and an accumulation of iron in certain tissues such as the liver, pancreas, and heart. The signs and symptoms of hemochromatosis are similar to those of iron overload in tissues caused by high dietary intake of iron or other non-genetic metabolic abnormalities, but are often increased in severity.\r\n

Dietary Sources of Iron<\/h2>\r\n
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Table 1.3.12.2<\/b> Iron Content of Various Foods <\/em><\/p>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Food<\/strong><\/td>\r\nServing<\/strong><\/td>\r\nIron (mg)<\/strong><\/td>\r\nPercent daily value<\/strong><\/td>\r\n<\/tr>\r\n
Breakfast cereals, fortified<\/td>\r\n1 serving<\/td>\r\n18<\/td>\r\n100<\/td>\r\n<\/tr>\r\n
Oysters<\/td>\r\n3 oz.<\/td>\r\n8<\/td>\r\n44<\/td>\r\n<\/tr>\r\n
Dark chocolate<\/td>\r\n3 oz.<\/td>\r\n7<\/td>\r\n39<\/td>\r\n<\/tr>\r\n
Beef liver<\/td>\r\n3 oz.<\/td>\r\n5<\/td>\r\n28<\/td>\r\n<\/tr>\r\n
Lentils<\/td>\r\n\u00bd c.<\/td>\r\n3<\/td>\r\n17<\/td>\r\n<\/tr>\r\n
Spinach, boiled<\/td>\r\n\u00bd c.<\/td>\r\n3<\/td>\r\n17<\/td>\r\n<\/tr>\r\n
Tofu, firm<\/td>\r\n\u00bd c.<\/td>\r\n3<\/td>\r\n17<\/td>\r\n<\/tr>\r\n
Kidney beans<\/td>\r\n\u00bd c.<\/td>\r\n2<\/td>\r\n11<\/td>\r\n<\/tr>\r\n
Sardines<\/td>\r\n3 oz.<\/td>\r\n2<\/td>\r\n11<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nSource: Iron<\/a>.\r\n

Iron-Deficiency Anemia<\/h2>\r\n
\r\n\r\nIron-deficiency anemia is a condition that develops from having insufficient iron levels in the body resulting in fewer and smaller red blood cells containing lower amounts of hemoglobin<\/b>. Regardless of the cause (be it from low dietary intake of iron or via excessive blood loss), iron-deficiency anemia has the following signs and symptoms, which are linked to the essential functions of iron in energy metabolism and blood health:\r\n