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close this bookProtein-Energy Interactions (IDECG, 1991, 437 p.)
close this folderThe metabolic basis of amino acid requirements
View the document(introduction...)
View the documentAbstract
View the document1. Introduction: The nature of the problem
View the document2. Nutrient requirement models
View the document3. The Millward & Rivers requirement model: Qualitative aspects
Open this folder and view contents4. The variable extrinsic component of the maintenance requirement
View the document5. The anabolic drive
View the document6. Hormonal components of the anabolic drive
View the document7. Protein requirements: Formal statement
Open this folder and view contents8. The issue of protein quality
View the document9. Stable isotope studies
View the document10. Practical experience of biological values of dietary protein
View the document11. Urea salvage
View the document12. Indispensable amino acid requirements for the anabolic drive
View the document13. Conclusions
View the documentReferences

3. The Millward & Rivers requirement model: Qualitative aspects

One way of representing the model qualitatively is shown in Figure 3. In its simplest form, it includes needs for new tissue and maintenance. We view maintenance as a variable component, comprising both fixed functional demands and variable regulatory extrinsic components. It is defined operationally as the dietary intake needed to balance all losses, including those which occur on feeding protein.

There are three components which are functional demands or intrinsic. The first one is the fixed component relating to the net requirement, i.e., the need to deposit new protein. Conceptually this is straightforward. The other two are part of the maintenance needs. These are the intrinsic requirements for obligatory amino acid consumption in non-protein pathways, conceptually straightforward even if poorly understood, and the anabolic drive.