How to Evaluate Dietary Protein

Abstract

The presentation of a paper on “How to evaluate dietary protein” might be approached in a number of ways, depending upon the depth and breadth of the coverage given to specific, relevant areas that could reasonably be included under this title. The primary nutritional function of dietary protein is to furnish the indispensable (essential) amino acids and total nitrogen required for synthesis of tissue and organ proteins and many other nitrogen-containing compounds necessary for normal growth and function of the organism. Hence, in the first instance, it is usual to consider the different food proteins and protein sources in relation to their capacity to meet the amino acid and nitrogen requirements of the host. On the other hand, a more comprehensive evaluation of dietary protein on the overall nutritional health of the individual and of populations, requires an assessment of the possible effects of various food protein sources on the utilization of, and requirements for, energy yielding substrates and other individual essential nutrients (e.g., [1]). Because later papers in this symposium will be devoted to milk proteins with reference to the utilization of, and requirements for, minerals and other micronutrients, as well as considering use of milk proteins in relation to various aspects of clinical nutrition, we have chosen the first instance above as our principal focus with respect to the “evaluation of dietary protein”. In doing so, we will consider some recent research that, while still somewhat controversial (e.g., [2]), provides a new, and we believe, a more rational basis for judging the significance of milk proteins in human protein and amino acid nutrition.