Normal full term infants are born with a supply of iron that lasts for 4 to 6 months. Evidence is not available to establish a RDA for iron for infants from birth through 6 months of age. Recommended iron intake for infants from 0 to 6 months is based on an Adequate Intake (AI) of 0.27 milligrams (mg) per day that reflects the average iron intake of breastfed infants (1). Iron in human milk (breast milk) is well absorbed by infants. It is estimated that infants can use greater than 50% of the iron in breast milk as compared to typically less than 12% of the iron in infant formula (1). Cow milk is not only low in iron and poorly absorbed by infants, its use in infancy can cause gastrointestinal bleeding and iron loss from the body. For these reasons, cow milk should not be fed to infants until after age 1 (1). The American Academy of Pediatrics recommends that infants who are not breastfed or who are partially breastfed should receive an iron-fortified formula from birth to 12 months (1,17). Formulas that contain between 4.0 to 12 milligrams of iron per liter of formula are considered iron-fortified (17)
Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III-1988-91) and the Continuing Survey of Food Intakes by Individuals (1994-96 CSFII) indicate that diets of most adult men and post-menopausal women provide recommended amounts of iron (18-19). Diets of females of childbearing age, pregnant women, and women who breast-feed generally do not provide recommended amounts of iron.
When can iron deficiency occur?The World Health Organization considers iron deficiency the number one nutritional disorder in the world (20). It affects more than 30% of the world’s population(21-22).
When your need for iron increases or a loss of iron from bleeding exceeds your dietary iron intake, a negative iron balance may occur. Initially this results in iron depletion, in which the storage form of iron is decreased while blood hemoglobin level remains normal. Iron deficiency occurs when blood and storage levels of iron are low, and the blood hemoglobin level falls below normal(1).
Iron deficiency anemia may result from a low dietary intake, inadequate intestinal absorption, excessive blood loss, and/or increased needs(23). Women of childbearing age, pregnant women, older infants and toddlers, and teenage girls are at greatest risk of developing iron deficiency anemia because they have the greatest needs(20).
Individuals with renal failure, especially those receiving dialysis, are at high risk for developing iron deficiency anemia. This is because their kidneys cannot create enough erythropoietin, a hormone needed to make red blood cells. Iron and erythropoietin can also be lost with blood during dialysis, which can result in an iron deficiency. Extra iron and erythropoietin are usually needed to help prevent iron deficiency in these individuals(24-26).
Iron deficiency could also be caused by low vitamin A status. Vitamin A helps to mobilize iron from its storage sites, so a deficiency of vitamin A limits the body’s ability to use stored iron. This results in an “apparent” iron deficiency because hemoglobin levels are low,even though the body can maintain normal amounts of stored iron (27,28). While uncommon in the U.S., this problem is seen in developing countries where vitamin A deficiency often occurs.
The anemia that may occur with inflammatory disease differs from iron deficiency anemia. It occurs in people who have chronic infectious, inflammatory, or malignant disorders (29,30). It is not associated with a shortage of dietary iron, and may not respond to iron supplementation (30,31). A physician should manage anemia associated with an inflammatory disorder.
Signs of iron deficiency anemia include feeling tired and weak, decreased work and school performance, slow cognitive and social development during childhood, difficulty maintaining body temperature, and decreased immune function, which may decrease resistance to infection (1,32-35). During pregnancy, iron deficiency is associated with increased risk of premature deliveries, giving birth to infants with low birth weight, (36,37) and maternal complications (1,37).
