C. THE ESSENTIAL NUTRIENTS.The essential nutrients are Protein, Fat, Carbohydrates, and protective ingredients or Vitamins.1. Proteins are the body's building blocks. As the house builder uses various building materials toconstruct a house, proteins build and replace the body's tissue of muscle, nerves, tendons and all ofthe vital organs, etc. This is done in the form of amino acids. For instance, the lining of thegastrointestinal tract is renewed every three days.2. The protein built body must have fuel to consume as it moves about and also take care of the energydemands of the vital body functions. The body maintains a reserve of energy by converting fats toglucose and storing it in the liver.