Iron

Iron is the primary component of hemoglobin, which is the part of the red blood cell that carries oxygen from the lungs to the cells and carbon dioxide from the cells to the lungs. Iron is also an essential component of myoglobin, which is a receptor and storage point for some of the oxygen in the muscles. Iron is also essential to the intracellular cytochrome system, which is another part of energy production.

An adult's body contains from three to five grams of iron. About one gram of this is stored in the liver. When red blood cells are broken down at the end of their useful life, their iron content is salvaged fairly efficiently in most people. Nevertheless, iron losses still occur in sweat, hair, lost skin, bleeding, and excretion. A normal adult male loses about one mg. of iron a day, while a woman can lose from one to two mg. During menstruation, injury, and bleeding, significantly higher quantities are lost.

Since iron is needed by all the cells of the body, and since every cell depends on oxygen, a deficiency of iron can have widespread effects. Anemia is a result of iron deficiency: the amount of circulating hemoglobin is markedly diminished. The red blood cells become pale, and cannot deliver as much oxygen to the cells as may be needed. The general symptoms are pallor, weakness, easy fatigability, labored breathing on exertion, headache, palpitation, and persistent tiredness. Iron deficiency sometimes results in a form or pica (perverted appetite for an item not usually considered food). In this case, the appetite is for ice (pagophagia). Dry scaling of the lips, spoon nails, and hair fall can also occur.

Iron deficiency anemia has been found to depress the immune system. White blood cells are reduced in their bacteria-killing activity. In two groups of children with anemia and depressed immunity, iron supplements greatly improved their ability to fight off infections. Iron deficiency has been shown to enhance the growth of tumors induced in animals by chemicals or viruses. Iron deficiency also causes degeneration of the periodontal tissue in animals.

Iron in excess of nutritional requirements has also been shown to completely prevent the toxicity of cadmium in animals. Vitamin C's protection against cadmium toxicity has been shown to rely heavily on the vitamin's ability to increase the amount of iron that is absorbed and made available to the cells.

The RDA for iron is ten to fifteen mg. for infants, fifteen to twenty mg. for children, ten to eighteen mg. for adolescents and adults, and eighteen mg. for pregnant and lactating women. These figures are based on estimates of how much iron must be ingested to make up for average daily losses. (Normal daily losses are about one to two mg.) But not all the iron in the diet is absorbed. Nutrition scientists believe less than ten percent is absorbed, so to make up for losses of two mg., more than twenty mg. must be supplied in the diet. Of course, many factors can raise requirements, including pregnancy, blood loss, and injury. During the entire course of a pregnancy, for example, the fetus requires a total of from 300 to 500 mg. of iron for development. This is in addition to the mother's own needs. Supplements as high as sixty mg. per day, however, have been found to be inadequate to raise hemoglobin levels to normal in some pregnant women.

Iron is poorly absorbed in the presence of phosphates, oxalates, and phytates (common substances in foods). Egg yolks impair iron absorption. Iron from animal sources is absorbed better than iron from plants, and absorption of iron from plants is enhanced in the presence of meat. Iron is also absorbed better in the presence of acids. Vitamin C (ascorbic acid) can boost iron absorption as much as tenfold when ingested at the same meal.

Natural sources of iron include liver, heart, kidney, lean meats, shellfish, dried beans and fruits, nuts, green leafy vegetables, whole grains, and blackstrap molasses. Some studies have found that the iron used to fortify processed cereals is poorly absorbed. Iron in mother's milk is five times more efficiently absorbed than iron in cow's milk or formula. Assuming a nursing mother has sufficient iron stores, a breastfed infant does not need iron supplements.

Iron supplements are available in a wide range of doses, from one mg. to sixty mg. or more, and a wide variety of forms: ferrous sulphate, ferrous glaciated, ferrous fumarate, etc. Iron is also available in syrup form, sometimes mixed with vitamins.

Where is it found ?

The most absorbable form of iron, called "heme" iron, is found in oysters, meat, poultry, and fish. Nonheme iron is also found in these foods, as well as in dried fruit, molasses, leafy green vegetables, wine, and most iron supplements. Acidic foods (such as tomato sauce) cooked in an iron pan can also be a source of dietary iron.

Who is likely to be deficient ?

Vegetarians eat less iron than nonvegetarians, and the iron they eat is somewhat less absorbable. As a result, vegetarians are more likely to have reduced iron stores. However, iron deficiency is not usually caused by a lack of iron in the diet alone; an underlying cause, such as iron loss in menstrual blood, often exists.

Pregnant women, marathon runners, people who take aspirin, and those who have parasitic infections, hemorrhoids, ulcers, ulcerative colitis, Crohn's disease, gastrointestinal cancers, or other conditions that cause blood loss or malabsorption are likely to become deficient.

Individuals who fit into one of these groups, even pregnant women, shouldn't automatically take iron supplements. Fatigue, the first symptom of iron deficiency, can be caused by many other things. A nutritionally oriented doctor should assess the need for iron supplements, since taking iron when it isn't needed does no good and may do some harm.

How much to take

If a nutritionally oriented doctor diagnoses iron deficiency, iron supplementation is essential. A common adult dose is 100 mg per day. When iron deficiency is diagnosed, the doctor must also determine the cause. Usually it's not serious (such as normal menstrual blood loss or blood donation). Occasionally, however, iron deficiency signals ulcers or even colon cancer.

Many premenopausal women become marginally iron deficient unless they supplement with iron. Even so, the 18 mg of iron present in most multiple-vitamin/mineral supplements is often adequate.

Side effects

Huge overdoses (as when a child swallows an entire bottle of iron supplements) can be fatal. Keep iron-containing supplements out of a child's reach. Hemochromatosis, hemosiderosis, polycythemia, and iron-loading anemias (such as thalassemia and sickle cell anemia) are conditions involving excessive storage of iron. Supplementing iron can be quite dangerous for people with these diseases.

Supplemental amounts required to overcome iron deficiency can cause constipation. Sometimes switching the form of iron, getting more exercise, or treating the constipation with fiber and fluids is helpful. Sometimes the amount of iron must be reduced if constipation occurs.

Some researchers have linked excess iron to diabetes, cancer, increased risk of infection, systemic lupus erythematosus (SLE), exacerbation of rheumatoid arthritis, and heart disease, though a review of the best studies has found no link. None of these links has been proven. Nonetheless, too much iron causes free radical damage, which can cause or exacerbate most of these diseases. People who are not iron deficient should not supplement iron when potential risks might exist and no benefit can be found.

Caffeine, high-fiber foods, and calcium supplements reduce iron absorption. Vitamin C slightly increases iron absorption. Taking vitamin A with iron helps treat iron deficiency, since vitamin A helps the body use iron stored in the liver.

Deferoxamine is a medication that binds to some metals, including iron, and carries them out of the body. It is used to treat acute iron poisoning, chronic iron overload, and aluminum accumulation in people with kidney failure. People taking deferoxamine to treat iron overload must not take iron supplements, including the amounts found in many multivitamin/minerals.

Penicillamine binds metals (including copper and iron) and carries them out of the body. When penicillamine and iron are taken together, penicillamine absorption and activity are reduced. Four cases of penicillamine-induced kidney damage were reported when concomitant iron therapy was stopped, which presumably led to increased penicillamine absorption and toxicity.

Back To Top