Bio-utilization of protein, calcium and zinc from diets based on rice and beans, in human beings

Nine male healthy adults volunteers of average body weight 69.51 +/- 11.59 kg were submitted to 3 experimental diets: I complete diet, containing rice and beans (RB): II--low protein, low calcium: III--vegetable diet containing RB. The diets were consumed "ad libitum". The total energy intake in each dietary period were: 46.04 +/- 9.18; 37.57 +/- 9.04; 55.27 +/- 7.18 respectively. The average free choice for the proportion of rice/beans was 1.22 and 1.35 in the periods I and III. The protein balance was positive only for the diet I and the balance of calcium was positive in diets I and II. Zinc didn't attained positive balance neither in diet I. It is suggested that the presence of beans in diets I and III plays an important role in decreasing the bio-utilization of the studied nutrients.