"The Protein Book" by Lyle McDonald

• Proteins are organic compounds made up of carbon, hydrogen, oxygen and nitrogen. The nitrogen part of protein is what not only makes a protein a protein but also sets it apart from both carbohydrate and fats.
• Generally speaking, animal source foods provide the most concentrated source of protein.
• Chemically speaking, many molecules in the body come in one of two different shapes, D- or L-. In the human body, only the L-form of nutrients is used; quit in fact, the D-form of some nutrients can be toxic to the body.
• Protein powders come in three primary forms which are isolates, concentrates, and hydrolysates. Protein concentrates typically contain roughly 80% protein with 5-6% carbohydrate and fat, while isolates may contain up to 90% protein. Hydrolysates are simply isolates or concentrates which have been pre-digested (digestion of protein is called hydrolysis) by subjecting them to specific enzymes.
• Proteins are made up of individual components called amino acids (AAs) that are attached together in long chains.
• Individual amino acids are referred to as peptides.
• In dietary terms, an essential nutrient is one that is not only required by the body for survival but cannot be made by the body; thus it is essential that they are obtained from the diet.
• Essential amino acids: lysine, isoleucine, leucine, valine, threonine, methionine, phenylalanine, tryptophan.
• Protein’s primary use in the body is structural; that is, protein is used for the production of other substances in the body.
• Most protein digestion actually occurs in the small intestine where protein is broken down into smaller and smaller amino acid chains via a variety of protein digesting enzymes.