Evaluation of the EDTA-washed diet for use in the experimental production of zinc deficiency in human subjects.

Ethylenediaminetetraacetate (EDTA) is known to bind zinc (Zn) and other metals. EDTA-washed soy protein-based diet has been extensively used as a dietary model for the production of Zn-deficiency in human subjects as well as in experimental animals. The present study was conducted to test this diet for possible contamination with EDTA (inhereted by washing procedure) and also to evaluate it for its acceptability and palatibility by human subjects. In the first experiment, EDTA-washed soy protein-based diets were prepared as previously described (repeated washing with EDTA-sodium salt followed by washing with deionized water and filteration), but 14C-EDTA was used. Scintillation counter analysis showed no traces of 14C in the prepared diet (100% of the 14C activity was recovered in the filtrate). In the second experiment, the diets were prepared using inactive EDTA, then fed to 10 volunteers for sensory evaluation. Results of this trial showed that the palatibility and acceptability of these diets are generally very poor. In conclusion, the use of EDTA-washing procedure did not result in any contamination of the soy assay protein with the EDTA. However, the present dietary model may not be used to induce zinc deficiency in human volunteers on a long term basis since the palatibility of the washed product is poor.