Dietary phytate and mineral bioavailability

The relation between the dietary phytate (InsP6), mineral status and InsP6 levels in the organism, using three controlled diets (AIN-76A, AIN-76A + 1% phytate, AIN-76A + 6% carob seed germ), are studied. AIN-76A is a purified diet in which InsP6 is practically absent. No important or significant differences in the mineral status (Zn, Cu, Fe) of blood, kidneys, liver, brain and bone, were observed, except iron in the brain. Thus, the amounts of iron found in the brain of rats fed AIN-76A + 1% InsP6 were significantly inferior to those found in rats fed AIN-76A diet. The amounts of InsP6 found in organs of rats fed AIN-76A diet became very low or even undetectable while the ones found in rats fed diets that contained 1% and 0.12% (AIN-76A + 6% carob seed germ) InsP6, were considerably higher and similar. Moreover the majority of rats fed AIN-76A diet exhibited calcifications at the corticomedullary junctions, whereas no calcifications were detected in rats fed the other two diets. From these results, it can be deduced that there was no important adverse effects on mineral status as a consequence of the presence of InsP6 in the studied diets. Besides, considering that a 0.12% InsP6 contained in the AIN-76A purified diet through the addition of a 6% of carob seed germ to this diet, produced the same beneficial effects as the direct addition of a 1% of InsP6 and no negative effects on mineral status was observed, it can be concluded that the value of the presence of InsP6 at adequate amounts in the diet is remarkable and must be favourably considered.