Iron deficiency is one of the most prevalent nutritional problems in the world. Iron compounds are used for the prevention and treatment of this deficiency. A double-blind randomized crossover study with 12 volunteers was carried out to compare the effect of three iron compounds, ferrous glycine chelate (GLY), ferric EDTA (EDTA), and ferrous sulfate (FS) on serum iron, and to examine serial serum iron levels. The products were offered as tablets, and blood samples were drawn hourly for 4 hours. FS produced higher serum iron levels than EDTA or GLY ( P <0.05). Data for GLY and EDTA were similar. The areas under the curve (AUC) for serum iron for the different compounds gave AUC FS > AUC GLY = AUC EDTA ( P < 0.05). Iron from FS had a significantly greater bioavailability than for the other two compounds.