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

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.
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.
The standard curve showed a linear equation: Ferritin (ng)/protein (mg) = (5.96 × bread Fe) 11.55, R2=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%.
This data can be potentially usable to adjust the amount of absorbable iron in the target population for fortification programs.