Effect of multiple fortification on the bioavailability of minerals in wheat meal bread.

Bioavailability of calcium, iron and zinc as calcium carbonate (CaCO3), ferrous sulfate (FeSO4) and zinc sulphate (ZnSO4) @ 1,000, 40 and 20 mg kg(-1) respectively from fortified bread of 72% extraction straight grade flour was assessed. Fortified bread diets were fed to 64 female Sprague-Dawley Albino rats for a period of 28 days. The retention of Ca, Fe and Zn was measured in plasma, femur and liver tissues of rats. The results showed that the feed intake and live body weight of the experimental animals increased significantly with the time period. The Ca levels in plasma and liver did not change significantly while in femur, Ca retention changed significantly with changing type of the fortificants. Similarly, the results for percent apparent absorption (AA) of Ca also remained unchanged (P < 0.05). The Fe and Zn levels were significantly higher in the plasma, liver and femur of rats fed Fe and Zn fortified bread. Interaction of Ca, Fe and Zn resulted in their decreased bioavailability. However Ca, Fe and Zn absorption was higher in the rats fed triple fortified diet compared with those fed unfortified bread diet. This negative interaction did not appear to be great enough to discourage multiple fortification of flour to address minerals malnutrition in the vulnerable groups.