Evaluation of Iron Bioavailability in Caco-2 cell Culture Model: Modification of the Original Method

Background and Objectives: In the original in vitro method for evaluation of iron bioavailability using caco-2 cell model, ferritin formation by cells is considered as a functional indicator of both absorption and utilization of iron. However, as iron is measured in the tested material and then ferritin concentration is measured in caco-2 cell lysate, it is almost impossible to have a concrete measure of iron bioavailability because the percent of absorbable iron cannot be calculated by the concentration of iron in caco-2 cell lysate. To overcome this problem, the original method was modified by using ferrous sulfate tablet as a standard and also including blank well in the cell culture plate to subtract the baseline ferritin concentration from the ferritin concentration of other wells. Materials and Methods: To evaluate iron bioavailability in this model, one kind of Iranian traditional breads (Sangak) was used. Standard curve was plotted using iron concentration and ferritin/protein ratio in the X and Y axes, respectively. Results: The standard curve showed a linear equation: Ferritin (ng)/protein (mg) = (5.96 × bread Fe)+ 11.55, R=0.989. Using this equation, the bioavailability of iron from the tested bread was 79.76 ± 11.5% of ferrous sulfate. Considering that the reported iron bioavailability from ferrous sulfate is about 10%, bioavailability of iron from the bread could be regarded 8%. Conclusions: This data can be potentially usable to adjust the amount of absorbable iron in the target population for fortification programs.