In the human body, iron is present in all cells and has several vital functions: as a carrier of oxygen to the tissues from the lungs in the form of hemoglobin; as a transport medium for electrons within the cells in the form of cytochromes and as an integral part of enzyme reactions in various tissues. Too little iron can interfere with these vital functions and lead to morbidity and death. This book presents current research from across the globe in the study of iron deficiency, including iron deficiency anemia in pregnant women and in gastric bypass surgery patients; the metabolic adjustment under Fe deficiency in roots of dicotyledonous plants and strategies for the fortification of food with iron.