This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition and Health, Subject name: Social & Preventive Medicine
Which of the following method of assessment of quality of proteins gives complete assessment of protein quality? 
Select and explain. 
A. Biological value, B. Net protein utilization, C. Digestibility co-efficient, D. Amino acid score
B: Net protein utilization
Answer: B: Net protein utilization 
Explanation: Ans. B. Net protein utilization. (Ref. Park's Textbook of PSM 22nd/pg. 588)Discussion:The quality of protein is assese23d by comparison to the reference protein which is usually egg protein.Two methods of ass of protein quality are amino acid score and Net Protein Utilization.# Amino acid score- measure of the concentration of each essential amino acid in the test protein expressed as % of that amino acid in the reference protein.# Net Protein Utilization- it is a product of digestibility coefficient and biological value divided by 100. The NPU gives a more complete expression of protein quality than amino acid score. NPU = N retained by the body/N intake x 100. In calculating protein quality, 1 gm of protein is assumed to be equvivalent to 6.25 g of N. If NPU is low, the protein req is high and vice versa. The NPU of the protein of Indian diets varies between 50-80.