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Iron

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The mineral iron has many functions in the body.
Iron from the diet is an essential part of hemoglobin - the substance which carries oxygen in the blood. It is therefore essential at all stages of life for blood to work efficiently.  If the body’s store of iron is low and there is too little iron in the diet to form new red blood cells, the symptoms of iron deficiency anemia will start to develop. Iron deficiency anemia can make people feel tired, weak, lethargic, irritable and less able to concentrate, as well as muscle fatigue and shortness of breath. The major changes that occur are behavioral, cognitive and psychomotor deficits and decreased immune function. These symptoms are followed by psychomotor and cognitive impaired skills. This causes shortened attention span and may impair learning. Even the slightest case of iron deficiency anemia, before noticeable symptoms, can slow cognitive development. Some evidence also shows that iron deficiency anemia leads to decreased immune functions.  Another symptom of anemia, called pica, is the desire to eat unusual things, such as ice, clay, cardboard, paint, or starch. Advanced anemia may also result in lightheadedness, headaches, ringing in the ears (tinnitus), irritability, pale skin (due to a lack of red blood cells in the body), unpleasant sensations in the legs with an uncontrollable urge to move them (restless legs syndrome), and getting winded easily.
 

Iron deficiency anemia is probably the most common nutritional deficiency in the world - it is estimated that at least 500 million people are affected.

In children, iron deficiency is usually the result of an inadequate iron intake and can affect their behavior and development.

In adults, iron deficiency is most commonly caused by chronic blood loss, such as with heavy menstruation or intestinal bleeding from peptic ulcers, cancer, or hemorrhoids.
 

FOOD HAS TWO FORMS OF IRON

Dietary iron is available in two valence states, Fe2+ (ferrous) and Fe3+ (ferric). The
majority of ferrous iron is found in heme iron and the majority of ferric iron is found in
non-heme iron. Heme iron is found in meats, poultry, and fish. Nonheme iron is found in both plant and animal foods.
 

OXIDATION OF IRON

Iron ions undergo two important changes of oxidation state during digestion and absorption.

The first change occurs in the stomach where iron (Fe3+) is reduced to iron (Fe2+ ).  This reduction is favored by the low pH. Reducing agents, such as ascorbic acid, assist this process.  Reduction is important because iron (Fe2+) dissociates from ligands more easily than            iron (Fe3+).

   The second change occurs in the duodenum.  The duodenum is bicarbonate-rich, and alkaline.  In the alkaline environment heme is absorbed directly by the mucosal cells. Within the cells, the iron dissociates from it. Free iron (Fe2+) ions are oxidized to iron (Fe3+), which is taken up by the mucosal cells in substantial amounts under all circumstances of nutritional iron status.

 

ABSORPTION

Heme iron is more easily absorbed by the body than nonheme iron. However, heme iron can also promote the absorption of non-heme iron. Therefore, eating beef and beans, for example, is good for providing adequate absorption of both types of iron.

Vitamin C also promotes iron absorption. This is true for both heme and nonheme iron. It is, therefore, beneficial to consume citrus fruits or juices, which are high in vitamin C, with foods that contain iron. For example, a meal might include a lean steak (heme iron source), baked potato (nonheme iron source), broccoli (nonheme iron source), and an orange (vitamin C source) for a good iron intake. You may absorb twice as much iron with just 50 mg of vitamin C, the amount in 1/2 cup of strawberries, orange juice, or broccoli.

Eating DAIRY FOODS while taking IRON may result in decreased iron effectiveness.
There are specific foods that interact with iron. These foods include but are not limited to milk, cheese, yogurt, or cottage cheese. It is recommended that you avoid taking any iron supplement with dairy foods.
 

Phytic and tannic acids are two food components that, when consumed in large amounts, prevent the absorption of iron. Phytic acid is found in rye bread and other foods made from whole grains. Phytic acid is also found in nonherbal teas. Tannic acid is found in commercial black and pekoe teas, coffee, cola drinks, chocolate, and red wines. You absorb up to 40% less iron with coffee, and up to 70% less with tea.
 
 

HIGH IRON FOODS

High in iron: liver, beef, ham, brewer's yeast, legumes, lima beans, kidney beans, dark green leafy vegetables, dried fruits (apricots, peaches, raisins, prunes), sardines, potato skin, fortified cereals.

 

IRON SUPPLEMENTS

There are many different kinds of iron supplements. However, iron supplements should only be taken when there is a true deficiency of iron and only under medical supervision.
General multivitamins often have iron and other minerals added to them in moderate amounts. If otherwise healthy, this amount of iron is probably not harmful. If iron is to be avoided, multivitamins containing iron should not be used.  Please note that it is important to keep iron and multivitamin supplements safely away from a child's reach. If ingested, severe poisoning can occur.
 
 

TOO MUCH IRON

Iron is stored in the body and large amounts can be toxic. The amount absorbed in the intestine is usually carefully regulated. However, people are usually advised to consult their doctors before taking iron supplements.

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References:

Cook JD (1990) Adaptation in iron metabolism. American Journal of Clinical Nutrition; 51:301-8

Hallberg L, et al (1991) Calcium: effect of different amounts on non-haem and haem-iron absorption in man. American Journal of Clinical Nutrition 53: 112-119

Hallberg L, et al. (1992) Calcium and iron absorption: mechanism of action and nutritional importance. European Journal of Clinical Nutrition 46: 317-327

Reddy MB, et al (2000) Estimation of non-haem iron bioavailability from meal composition. American Journal of Clinical Nutrition 71: 937-43

Hallberg L, et al (2000) Prediction of dietary absorption: an algorithm for calculating absorption and bioavailability of dietary iron. American Journal of Clinical Nutrition 71: 1147-60

Zijp IM, et al (2000) Effect of tea and other dietary factors on iron absorption. Critical Reviews in Food Science and Nutrition 40: 371-398

Powell JJ, et al (1994) Mechanisms of gastrointestinal absorption: dietary minerals and the influence of beverage ingestion. Food Chemistry 51: 381-8