ABSTRACT
In addition to studies of whole body and muscle protein metabolism in relation to human aging some attention has been given to the effects of increasing age on the metabolism of individual proteins, notably albumin. The responses of body protein and amino acid metabolism to changes in dietary protein and energy intakes will be described in order to establish a metabolic basis for assessing methods and approaches used for estimating the dietary requirements for protein in human adults. However, because many of the specific aspects of protein and amino acid metabolism cannot yet be related to the more practical issues of protein and amino acid requirements, the latter have been explored in a limited number of ways. Thus measurements of the intake of amino acids or of dietary nitrogen and the output of nitrogen via the major excretory routes, urine, feces and integument, have been extensively applied in studies of whole body protein metabolism in human adults.
