Which of the following statement is TRUE about NPU (net protein utilization), used in protein quality assessment?: (A) It is the ratio of energy from protein to total energy in diet, (B) It is the ratio between nitrogen retained by the body and total nitrogen intake multiplied by 100, (C) It is the amount of one amino acid per gram of a protein divided by the amount of same amino acid per gram of egg protein, (D) If the NPU is high the amount of protein requirement in diet is high
Answer is B. Net Protein Utilization (NPU) is the ratio between nitrogen retained by the body and total nitrogen intake multiplied by 100. It is a product of digestibility coefficient and biological value divided by 100. It gives a more complete expression of protein quality than the amino acid score. In calculating protein quality, 1 gram of protein is assumed to be equivalent to 6.25 g of N. Ref: Park's Textbook of Preventive and Social medicine, 19th Edition, Page 503.