Ethylenediaminetetraacetic acid (EDTA) does not increase iron uptake or ferritin synthesis by Caco-2 cells

Ethylenediaminetetraacetic acid (NaFe-EDTA) is a chelator capable of binding a wide variety of metals, with a high affinity constant for Fe(3+). NaFe-EDTA has been extensively studied and validated as an excellent choice for iron fortification programs and extensive research has demonstrated its high bioavailability specially for cereal based foods. To further evaluate the usefulness of this compound we performed iron uptake experiments with EDTA using the Caco-2 cell system. Cells were incubated in PBS at pH 5.5 or 7.0, containing or not ascorbic acid. Different sources of EDTA, different concentrations of NaFe-EDTA and the inclusion of another iron compound as electrolytic iron, were tested. Also, the ferritin content of Caco-2 cells 24h after 1h incubation with iron compounds was evaluated. Except for the addition of ascorbic acid, under the experimental conditions used, Caco-2 cells were not capable of obtaining iron from NaFe-EDTA. Furthermore, iron uptake from electrolytic iron was inhibited when Na(2) or K(2)-EDTA were included. Ferritin determinations to Caco-2 cells evaluated 24h after 1h incubation periods, showed that NaFe-EDTA did not induce new ferritin synthesis, since iron did not enter the cells. Further studies are required to evaluate incorporation of iron from NaFe-EDTA to a common iron pool and the requirements for iron uptake by Caco-2 cells.