Iron (Fe) is an essential trace mineral in humans. It is involved in the entire process of breathing, including oxygen transport and electron transport. Iron-deficiency, which can lead to anemia, is the most common nutritional disorder in the world. Approximately 25% of the world’s population is Iron-deficient. In addition to its fundamental roles in respiration and energy production, Iron is involved in DNA synthesis and may also play roles in normal brain development, and in immune function.
Iron is also involved in the synthesis of collagen and in the synthesis of serotonin, dopamine and norepenephrine. There is also some evidence Iron may diminish learning problems and enhance cognition in some children and adolescents with Iron deficiency. In one study, the effects of iron supplements were tested in adolescent girls with non-anemia iron deficiency to see if they might improve cognition. This was a double-blind, placebo-controlled trial. Subjects were randomized to receive 650 mg of Iron twice daily, or a placebo for eight weeks. Those with Iron supplementation were reported to perform significantly better than those of the placebo group on tests related to verbal learning and memory.
The remainder is in your body’s tissues as part of proteins that help your body function. Adult men and post-menopausal women lose very little iron except through bleeding. Women with heavy monthly periods can lose a significant amount of iron.
Its major function is to combine with protein and copper in making hemoglobin. Hemoglobin transports oxygen in the blood from the lungs to the tissues which need oxygen to maintain basic life functions. Iron builds up the quality of the blood and increases resistance to stress and disease. It is also necessary for the formation of myoglobin which is found only in muscle tissue. Myoglobin supplies oxygen to muscle cells for use in the chemical reaction that results in muscle contraction. Iron also prevent fatigue and promotes good skin tone.
Severe iron deficiency results in anemia with small, pale, red blood cells that have a low hemoglobin concentration. Iron deficiency anemia in pregnancy increases the risk of premature and low birth weight babies. In young children, iron deficiency is associated with behavioral abnormalities (such as reduced attention span), and reduced cognitive performance that may not be fully reversible by iron replacement. In adults, severe iron deficiency anemia impairs physical work capacity. In the US, iron deficiency anemia is relatively rare, but affects 5% of women 20 – 49 years old. Moderate iron deficiency without anemia is most common in 1 – 2 year-old children (9%), and females 12 – 49 years old (9 – 11%), reflecting rapid growth or menstrual iron loss, and is less common in other groups. Also may result in weakness, paleness of skin, constipation, anemia.
The 1989 Recommended Dietary Allowance (RDA) for iron is 6 mg for infants through 6 months of age; 10 mg for older infants and children through 10 years old, men 18 years and older, and women over 50 years; 12 mg for 11-18 year-old males; 15 mg for 11-50 year-old females, including nursing mothers; and 30 mg (a recommendation which requires supplementation) during pregnancy. The 1989 – 91 USDA Food Consumption Survey indicates that average diets meet or exceed the RDA for all groups except 1-2 year-old children (91% of RDA) and women ages 12-49 years (75-80 % of RDA). Iron supplements are not needed by most people and, because of potential adverse effects of excessive iron, should not be taken by adult men or postmenopausal women without demonstrable need.
In the US, grain products are a principal source of dietary iron, followed by meat, poultry and fish, then vegetables, then legumes, nuts, and soy. Red meat is a rich source of iron that is well absorbed. Heme iron (about 40% of the iron in meat, poultry, or fish, and 7-12% of the iron in US diets) is 15-45% absorbed, depending on iron stores (persons with low iron stores compensate by absorbing more iron). Nonheme iron, the remaining majority of dietary iron, is 1-15% absorbed, depending on iron stores and on absorption enhancers (e.g., ascorbic acid, an unidentified factor in meat, poultry and fish) or inhibitors (e.g., phytic acid in whole grains and legumes, polyphenols in tea, coffee, or red wine, calcium in dairy products or supplements) eaten concurrently. In the US refined grain products are enriched routinely with iron. Iron-fortified formula or cereals are useful in preventing iron deficiency in infants.
Iron supplements intended for other household members are the most common cause of pediatric poisoning deaths in the US. In populations of European origin, approximately 1 in 300 people have hemochromatosis, a genetic abnormality of excessive iron stores. Ten percent of these populations carry a gene (are heterozygous) for hemochromatosis. Researchers are testing hypotheses that high iron stores may increase the risk of chronic diseases, such as cancer and heart disease, through oxidative mechanisms.