Balancing the Benefits and Risks of Iron Fortification in Resource-Constrained Settings

Abstract

T he need for dietary sources of iron is substantiated by an abundance of data, some of which is discussed below. Iron is an essential nutrient that must be supplied by the diet. Iron functions as a component of a number of proteins, including enzymes and hemoglobin (Hb), which are essential for the transport of oxygen to tissues throughout the body. Without dietary sources of iron, a deficiency state will ultimately develop. With advancing iron deficiency, eventually iron stores will be depleted and iron-deficiency anemia (IDA) will develop. Depending on the timing and severity of the anemia, adverse outcomes will ultimately become evident (tissue hypoxia, heart failure, etc). Most experimental and epidemiologic evidence related to anemia and iron deficiency derives from studies where iron deficiency is severe enough to cause a measurable decrease in Hb concentration, and, thus, anemia. Once anemia is present, it is still difficult to determine whether measureable functional abnormalities are a specific consequence of the anemia per se, presumably because of some impairment of oxygen delivery, or the result of concomitant tissue iron deficiency. TheWorld Health Organization (WHO) estimates that anemia affects one-quarter of the world’s population and is concentrated within preschool age children and women. Iron deficiency is a particularly challenging problem for developing nations in Asia and Africa. Although there is agreement about the need for iron, WHO and various national organizations disagree about the following two issues: the amount of iron that an infant needs to ingest to prevent deficiency and the degree (or severity) of anemia (or iron deficiency) at which adverse functional outcomes begin to occur in an infant. A third area of debate relates to the safety of dietary iron intake, especially in infants and children at risk of infection or who might be immunologically compromised because of poor nutritional status. This review summarizes research on these issues that is particularly relevant to resourceconstrained settings.