Unit 6
Protein: Amino Acids

Protein (Greek proteios, “of prime importance”) was the first substance recognized as vital to cells. Proteins have therefore been highly regarded, being seen as supplying strength and power to the body.

Protein is, of course, an important nutrient required by all the body cells. Proteins are constituents of muscle tissues, soft tissues, bones, teeth, blood and other body fluids, and enzymes. However, dietary proteins are often overvalued, and treated as nutrients with fantastic properties, especially for muscle building.

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

This unit consists of the four sections listed below.

• Section 6.1  Chemistry
• Section 6.2  Digestion, Absorption, and Protein Quality
• Section 6.3  Functions and Health Effects
• Section 6.4  Proteins in the Diet