A comparison of physical properties, screening procedures and a human efficacy trial for predicting the bioavailability of commercial elemental iron powders used for food fortification

Elemental iron powders are widely used to fortify staple foods. This paper summarizes physical and chemical measurements that were conducted to assess the bioavailability of these iron powders relative to ferrous sulfate, along with validation of these assessments from a study with human subjects. Commercial elemental iron powders varied in bioavailability depending on the manufacturing process. Measurements of particle surface area and of solubility compared well with measurements conducted with animal absorption and with improvement of iron status in Thai women. The dissolution rate of the elemental iron powders in dilute acid, according to a standardized procedure, may be useful as an estimate of bioavailability. Carbonyl and electrolytic iron were found to have the best bioavailability of the iron powders, and reduced forms of iron were generally less bioavailable. This research will be useful in selecting iron products to fortify foods in areas of the world that need dietary iron fortification to fight a high incidence of iron deficiency and iron deficiency anemia.