To evaluate the calcium effect on iron absorption and genes expression involved in non-heme iron absorption by Caco-2 cells.
The cells were exposed for 1 h to 2 mM solutions of varying concentrations of iron and calcium (calcium:iron molar ratios: 0:1 to 1000:1). Gene expression was determined by qRT-PCR. Changes in expression levels over control (calcium:iron=0:1) were evaluated by one-way ANOVA; significant considering a value of p <0.05.
Exposure to calcium significantly increased the expression of genes involved in uptake of non-heme iron (ANOVA p = 0.003 and 0.016 for Dcytb and DMT1, respectively). Gene expression of FPN (efflux protein of heme iron and nonheme) decreased by exposure to calcium (ANOVA <0.001).
Calcium increased gene expression associated with no heme iron uptake and decrease gene expression of FPN. The change in ferroportin may explain the inhibitory effect on the absorption of both type of dietary iron (heme and non-heme) shown in humans. Modifications in gene expression donÂ´t affect iron absorption. This open the possibility of iron-calcium combined supplementation for higher risk populations like pregnant and women in reproductive age.