Iron deficiency is the most prevalent micronutrient deficiency in the world today. It affects millions of individuals throughout the life cycle, particularly infants and pregnant women, but also older children, adolescents, and women of reproductive age. Living organisms require iron for their cells to function normally. Iron is needed for the development of vital tissues - including the brain - and for transporting and storing oxygen in hemoglobin and muscle myoglobin. Iron deficiency anemia is the severe form of iron deficiency. It can result in low resistance to infection, impaired psychomotor development, and cognitive function in children, poor academic performance, as well as fatigue and poor physical/work endurance. In addition to the above, iron deficiency anemia in pregnancy can result in a low-birth-weight infant. Three intervention strategies are available to prevent iron deficiency and, therefore, iron deficiency anemia. These are supplementation, dietary diversification, and both targeted and untargeted food fortification. Nineteen countries in the Americas have a national food fortification program, in which iron and other micronutrients are added to at least one widely consumed food that is often wheat and/or corn flour. Table 1 shows the iron compounds added to the flours. Each iron compound has different properties and characteristics, which influence its bioavailability, as is discussed later. A number of countries also currently implement fortification programs targeted to specific groups of the population, primarily infants and young children age 6 to 24 months and school-age children.