Bioavailability of mineral elements in the brazilian basic food system of rice and beans

Mineral balance-sheets and fortification tests were used to detect the limiting minerals and trace-elements in rice-bean (RB) diets in young rats. The animals were fed on diets of RB or RB with milk (RBM). The body weight gain, food intake and food conversion efficiency were significantly higher in RBM groups than in RB ones. The mineral trace element balance-sheet resulted in negative retention for manganese, iron, zinc, calcium, cobalt, copper, chromium, molybdenum, and phosphorus in the RB group, with a significative improvement only for calcium in the RBM group. Fortification of RB with calcium and phosphorus, or with zinc increased the growth rate. This is attributed to the low level of calcium in the RB diet and to the low bioavailability of calcium and zinc in the presence of phytic acid and fibre.