Unit 7
Protein and Amino Acids

Protein was the first substance recognized as vital to living cells. Proteins have, therefore, been highly regarded, being seen as supplying strength and power to the body. Proteins are an important nutrient required by all the body’s cells: they are constituents of muscle tissues, soft tissues, bones, teeth, blood and other body fluids, and enzymes. However, dietary protein is often overvalued and treated as a nutrient with fantastic properties, especially for muscle building.

This unit will provide an overview of proteins: their chemical characteristics, the processes of protein digestion and absorption, and protein quality. We will examine the functions of proteins in the body, the health effects of protein deficiency or excess, and the issue of protein quality for vegetarian diets. Finally, we will look at patterns of protein consumption and at intake recommendations.

Objectives

After completing this unit, you should be able to

1. identify the chemical nature of amino acids and proteins.
2. discuss the digestion and absorption of proteins.
3. list seven functions of protein.
4. explain how an amino acid is broken down if not needed for a protein-specific role.
5. explain three factors influencing protein quality.
6. discuss the importance of complementary proteins and mutual supplementation, and provide examples of them.
7. define nitrogen balance, and explain in what situations it will be positive, negative, or balanced.
8. list the major dietary sources of protein.
9. discuss the RDAs and recommended per cent calories for protein, and compare the protein intakes of Canadian adults to the recommendations.