Six Classes of Nutrients and Their Major Functions Protein Protein is responsible for growth, repair, maintenance and fuel. Not only does it build and repair body tissue, but it is also serves as a major component of enzymes, hormones and antibodies. Every cell in your body contains protein. There are literally thousands of different kinds of protein. Hormones, enzymes, structural components, immune components and muscle contractile molecules are all proteins.
Amino acids are the building blocks from which protein molecules are constructed.
Of the twenty amino acids, eight are called essential. Essential amino acids must be provided by your diet. Carbohydrates Carbohydrates provide a major source of energy for the body and are used to power muscular contraction and as a fuel for the central nervous system. Carbohydrates spare protein from being synthesized into glucose, and they are a metabolic primer for fat metabolism. Monosaccharides and disaccharides are also called simple sugars or simple carbohydrates, and polysaccharides are called complex carbohydrates.