A mixture of bran cereals, cassava leaf and eggshell powder has been used as an alternative diet supplement to fight malnutrition in low-income communities in Brazil. Due to the high phytic acid content there are some concerns about the bioavailability of nutrients in this mixture (MM). This study investigated the effect of dietary concentrations of protein and NaCl on the bioavailability of MM calcium and phosphorus. Undernourished rats were given deficient diet supplemented with MM, with or without the addition of protein and NaCl. Calcium and phosphorus were found to be bioavailable, since rats fed MM supplemented diet showed higher femur calcium and phosphorus contents than did deficient rats (P < 0.001). Increased dietary protein did not provide for any additional weight gain, while added NaCl did (P < 0.001). Dietary protein had a positive effect on the metabolism of calcium and phosphorus while NaCl favored diet acceptability.