How do I know if I'm getting too much or too little iron?
Either too much or too little iron can cause big trouble. In this country, health-conscious people may take too much iron rather than not enough. The current recommended daily dietary allowances for iron from the U.S. National Research Council are as follows:
Infants to 6 months: 6 milligrams
Infants 6 months to 1 year: 10 milligrams
Children 1 to 10: 10 milligrams
Males 11 to 18: 12 milligrams
Males 19 to 50 plus: 10 milligrams
Females 11 to 50: 15 milligrams
Females 51 plus: 10 milligrams
Pregnant women: 30 milligrams
Lactating women: 15 milligrams
The tolerable daily intake level for adults is 45 milligrams of iron, a level based on gastrointestinal distress as an adverse effect. Iron supplements at several times the recommended levels may be dangerous for those who absorb iron too easily.
Iron deficiency most commonly manifests itself as iron-deficiency anemia. Iron deficiency and iron-deficiency anemia can occur during periods of rapid growth or pregnancy and among women who are menstruating more than usual. It can also be associated with any type of intestinal loss of blood, frequent donation of blood or the inability to absorb iron efficiently.
Initial symptoms of iron-deficiency anemia are fatigue and lack of energy. Dizziness, weight loss and lowered immunity can also occur. The symptoms can be alleviated once the cause of the iron deficiency has been determined.
It is unlikely that iron toxicity can develop from an increased dietary intake of iron alone. Children have been known to develop iron toxicity by increased intake of iron supplements, however. Symptoms of iron toxicity are fatigue, anorexia, dizziness, nausea, vomiting, headache, weight loss, shortness of breath and a grayish skin color.
Hemochromatosis is a genetic disorder that affects the regulation of iron absorption. The incidence may be as high as five in 1,000 in Caucasians. Treatment consists of a low-iron diet, no iron supplements and regular blood removal.
Excess storage of iron in the body is known as hemosiderosis. The increased iron stores come from the consumption of excessive iron supplements or from receiving frequent blood transfusions rather than increased iron intake in the diet.
What are the best food sources of iron?
The sources of easily absorbed iron are animal products, known as heme iron. Iron from vegetables, fruits, grains and supplements nonheme iron is harder for the body to absorb.
Mixing some lean meat, fish or poultry with beans or dark leafy greens at a meal can improve absorption of vegetable sources of iron up to three times. Foods rich in vitamin C also increase iron absorption.
Some foods decrease iron absorption. Commercial black or pekoe teas contain substances that bind to iron so it cannot be used by the body.
Considering the amount of absorbable iron in a food is a more accurate way to calculate iron available to the body than simply recording the total iron content.
Sources that have high iron availability are oysters, liver, lean red meat (especially beef), poultry, dark red meat, tuna fish, salmon, iron-fortified cereals, dried beans, whole grains, eggs (especially egg yolks), dried fruits and dark, leafy green vegetables. Reasonable amounts are also found in lamb, pork and shellfish.
Nonheme iron is found in whole grains such as wheat, millet, oats and brown rice; lima beans, soybeans, kidney beans, dried beans and peas; seeds such as almonds and Brazil nuts; prunes, raisins and dried apricots; and broccoli, spinach, kale, collards, asparagus and dandelion greens.
What are the main functions of iron?
The mineral iron is an essential nutrient for humans because it is part of blood cells, which carry oxygen to all body cells. About 30 percent of the iron in our bodies is in storage to be readily available to replace lost iron.
Iron is essential to the formation of hemoglobin and myoglobin, which carry oxygen in the blood and the muscle. Iron is also part of many proteins and enzymes in the body.
Iron deficiency is the most common nutritional deficiency worldwide. Although full-blown anemia is rarely evident, partial deficiency is widespread.
Symptoms of decreased iron stores include general fatigue, shortness of breath, headache, irritability and lethargy. If you have constant, unusual signs of exhaustion, see your doctor.
There are many causes of such symptoms. Simply taking an iron supplement may not be the key to renewing your energy.
Who is most at risk of having low iron?
Those at risk for low iron stores include:
1. Women of childbearing age, due to menstruation.
2. Pregnant women, due to baby's needs and blood loss during childbirth.
3. Infants, who usually are born with iron stores to last about six months. An infant's iron needs are met by breast milk. A nonbreastfed infant's iron needs can be met with an iron supplement or iron-fortified infant formula. As babies move to solid foods, those containing high amounts of iron should be selected to prevent the development of iron deficiency.
4. Children between 1 and 4 years of age are at risk for developing iron deficiency because of rapid growth and a lack of sufficient iron in their diets unless iron-fortified foods or a supplement is available. Milk is a very poor source of iron. Children who drink large quantities of milk at the expense of other foods may develop "milk anemia." Limit milk to about a quart or less per day. Recommended milk intake is two to three cups per day for toddlers.
5. Adolescents traditionally have been prone to anemia because of rapid growth rates, erratic eating habits and concerns about body image.
6. Other groups. These include long-distance runners, whose demanding exertions may damage red blood cells, and strict vegetarians, because they do not eat animal products, which contain the most easily absorbed form of iron.
Susan Krumm is an Extension agent in family and consumer sciences with K-State Research and Extension-Douglas County, 2110 Harper St. She can be reached at 843-7058
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