[Analysis of the application of methods recommended by FAO/WHO 1973 for determining the protein quality in Chilean food. Effect of the dietary protein concentration].

The 1973 FAO/WHO Joint Expert Committee on Energy and Protein Requirements has recommended two methods to adjust the safe level of protein intake according to protein quality: chemical score and net protein utilization (NPU). However, the effect of protein concentration on protein utilization is not considered. The results of the present work, as well as those obtained by other investigators, show that there is an inverse relationship between protein concentration and protein utilization. The net protein utilization (NPU) at 10% of protein-calories or the chemical score adjusted by the nitrogen digestibility can be applied when results are to be projected to national average diets, which have values ranging between 9 and 13%. When it is necessary to evaluate the diet of specific relatively homogeneous population groups, the recommended method should use the NPU determined or calculated in each meal considering the level of protein concentration of the diet as eaten (NPU op). This method takes into account the amino acid complementation in each meal. The data on which these conclusions are based have been presented and discussed.