How much do you need?
Iron requirements depend on several factors, including sex and age. For example, adult men and postmenopausal women need less iron compared to children, adolescents, and women of childbearing age. Infants need very little iron while pregnant women need substantially more than others.
Information gathered from two major food surveys, the National Health and Nutrition Examination Survey (NHANES III 1988–1991), and the Continuing Survey of Food Intakes by Individuals (CSFII 1994–1996), yielded a lot of information about the nutrition status of the American population. As far as iron goes, adult men and postmenopausal women tend to consume the recommended dietary intake for iron. However, women of childbearing age and pregnant and breast-feeding women often do not consume enough iron in their diets.
The RDA is the daily intake of a nutrient that is sufficient to meet the requirements of approximately 98% of healthy individuals in a certain population. This table lists the RDAs for iron based on age and sex.
Healthy infants are born with iron stores that typically last them for four to six months. In addition to providing infection-fighting antibodies and important fatty acids, breast milk is also a good source of a well absorbed form of iron. The American Academy of Pediatrics recommends that infants who are not breast-fed receive an iron-fortified formula from birth until 12 months. Cow’s milk should not be fed to babies less than 12 months old because it is low in iron (a form that is also not well absorbed) and can cause infants to experience gastrointestinal bleeding and loss of iron. Once a baby starts to eat solid food, it’s important to give him foods high in iron to prevent iron deficiency.
Iron-deficiency anemia can occur when there is not enough hemoglobin in the blood. The World Health Organization reports that iron deficiency is the most common nutrition disorder in the world, and it’s estimated that more than 30% of the world’s population is affected. In the United States, approximately 5% of women and 2% of men have iron-deficiency anemia.
Insufficient iron in the body will eventually lead to iron-deficiency anemia. Here’s what happens: A lack of iron in the blood due to, say, a low dietary intake of iron, signals the body to draw from its iron reserves in the liver, spleen, and bone marrow. However, when iron stores in the bone marrow also become low, the marrow then cannot make enough hemoglobin for the red blood cells. The resulting red blood cells are small and carry too little oxygen for organs and tissues throughout the body, causing anemia.
Causes. Because anemia results from low stores of iron in the body, a health-care provider must first look for reasons why iron stores are low. Typically, low iron levels are the result of an inadequate intake of dietary iron, poor absorption of iron in the body, internal bleeding due to ulcers or cancer, heavy menstrual periods, or an increased need for iron because of the needs of a fetus during pregnancy, the demands of the growing bodies of children and adolescents, or an increased loss of iron during endurance sports.
People who are on kidney dialysis often become anemic. Diseased or malfunctioning kidneys can’t make enough of a hormone called erythropoietin, which is needed to make red blood cells. Erythropoietin and iron are also lost during the dialysis process. Therefore, people on dialysis typically need supplements of iron and erythropoietin to prevent anemia.
Iron-deficiency anemia can occur also due to a deficiency of vitamin A. Vitamin A helps the body use its stored iron. So, even if body stores of iron are normal, a lack of vitamin A prevents the body from accessing those stores to create hemoglobin. Vitamin A deficiency is rarely seen in the United States but is quite common in developing countries.