Iron Supplementation

September 15, 2011

Iron is a trace mineral that is vital for life but needed only in small amounts. Iron plays an important role in oxygen transport and energy production, and because of this, iron is a vital element in the daily diet. The average adult body contains about 4 g of iron, 3 g in active form and about 1 g in storage or transport form. About 70% of the active form of the iron is found in hemoglobin, myoglobin, and enzymes. The function of hemoglobin is to carry oxygen from the lungs to the other tissues and to take carbon dioxide back from the tissues to the lungs. The cytochrome enzymes help cells produce energy.

Iron in the oxidized or ferrous form is absorbed well compared to iron in the ferric form. Vitamin C (ascorbic acid) enhances iron absorption by converting ferric oxide to ferrous oxide, making it water soluble. Iron absorption increases with need, such as during periods of rapid growth in infancy, childhood, adolescence, and during pregnancy. When the body has enough iron, 10% of dietary iron is absorbed. This may increase to 12% or 13% when the body is iron deficient. Iron found in animal tissues is better absorbed than iron from vegetable sources. Tea and dietary fiber supplements slow iron absorption by forming insoluble iron compounds.

Iron deficiency results in anemia. Anemia is a condition in which the total hemoglobin content in the bloodstream is below normal. In anemia, the number of red blood cells may be low, or cell numbers may be normal if each red cell contains less hemoglobin than usual. Because of the reduced hemoglobin content, the blood carries less oxygen, which causes fatigue. A diet low in iron can cause iron-deficiency anemia, especially in infants, children, teenagers, and vegetarians. Iron deficiency can also be caused by chronic blood loss. Among women, heavy menstrual periods, closely spaced pregnancies, and breast-feeding can deplete the body’s iron stores. Some people may become iron deficient because they cannot absorb enough of the iron in their diet. This occurs in Crohn’s disease (an intestinal disease), or after surgical removal of part of the stomach. Certain drugs, foods, and caffeinated drinks interfere with iron absorption. Other dietary factors such as a lack of protein, calories, B vitamins, or vitamin C can lead to irondeficiency anemia. At four times in the life cycle, iron intake is often inadequate: (a) infancy, (b) periods of rapid growth in childhood and adolescence, (c) reproductive age and during menstrual periods, and (d) pregnancy.

The symptoms of iron deficiency include fatigue, weakness, and pale appearance. Hemoglobin is red, and when iron deficiency causes the hemoglobin level to fall, the skin, nail, and mucous membranes become pale. Heart symptoms like rapid heartbeat, heart murmurs, and enlargement of the heart will appear if the anemia is severe. Another symptom that can occur with anemia is pica, in which the person craves and eats substances like paper, starch, dirt, or ice. Anemia can also cause upward curvature of nails, brittle nails, or ridges in the nails.

Anemia is diagnosed by measuring the amount of hemoglobin in the blood. However, having anemia does not mean that low iron is the culprit. Further tests are needed to diagnose iron deficiency. These include measuring the total serum iron, total iron-binding capacity, and the ferritin level. In iron-deficiency anemia, the hemoglobin, serum iron, and serum ferritin are below normal level, while the total iron-binding capacity is above normal.

Symptoms of iron-deficiency anemia are reversible by replenishing the body’s iron stores. Prevention is the best treatment. Preventive measures for infants include iron supplements and introduction of fortified and enriched foods at the appropriate age. Pregnant women usually take iron supplement pills that contain ferrous sulfate until delivery. The supplements should be taken after meals. When iron deficiency is caused by poor absorption in the intestine, iron may be replaced through injections. The diet should be planned to increase iron intake and the intake of factors such as vitamins and animal protein that help in iron absorption. Avoid dietary factors that decrease iron absorption, like tea, phytates, and phosphates.

Even if symptoms of iron deficiency are present, do not take iron supplements without talking with your health care professional. If the iron loss is due to intestinal bleeding, taking iron pills may delay the diagnosis of a serious problem such as bleeding ulcer, or colon cancer. If the anemia is not due to iron deficiency, taking iron pills will not help the anemia, but may cause iron toxicity. Unnecessary iron supplements can also cause iron overload (hemochromatosis), in which iron is deposited in the liver and heart, causing liver and heart problems. It is difficult to overload with iron from food alone, because the intestines are usually effective in preventing excessive iron absorption. However, excessive amounts of iron can prevent the body from regulating iron absorption properly. Iron supplements are a leading cause of fatal poisoning in children. Always store iron supplements in child-safe containers out of reach of children. Iron supplements should only be used when tests show a deficiency of iron and a health care professional recommends what dose to take, and for how long.

SEE ALSO: Diet, Nutrition

Suggested Reading

  • Blashfield, J. F. (2002). Iron and the trace elements. Austin, TX: Raintree Steck-Vaughn.
  • Chopra, J. G., & Kevany, J. (1971). International approach to nutritional anemia. American Journal of Public Health, 61, 250-258.
  • Marsha, H. (1999). Vitamins, minerals, and dietary supplements. New York: John Wiley & Sons.

Tags: ,

Category: I