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Medicine LibreTexts

6: Proteins

In this chapter, we cover the structure and roles of protein, and explore the consequences of getting too little or too much protein in your diet. Tips for getting the right amount and quality of protein, as well as a look at special populations, such as the elderly and athletes, are also covered.

  • 6.1: Prelude to Proteins
    Protein is best used for vital body functions—eat just enough for your lifestyle needs. Some dieters use protein bars as a prime part of their diet, with the hopes of slimming their waistlines. Exercise cafes serve protein shakes to many of their patrons, who drink them for building muscle and enhancing exercise recovery.
  • 6.2: Defining Protein
    Amino acids differ chemically in the molecular composition of their side chains, but they do have some similarities. They are grouped into four different types: nonpolar, polar, acidic, and basic. Amino acids are also categorized based upon their nutritional aspects. Some are nonessential in the diet because the body can synthesize them, and some are essential in the diet because the body cannot make them. Proteins are polymers of amino acid monomers held together by peptide bonds.
  • 6.3: The Role of Proteins in Foods - Cooking and Denaturation
    Proteins provide food not only with nutrition, but also with structure and texture. When a protein denatures, its complicated structure unfolds into a strand of amino acids.
  • 6.4: Protein Digestion and Absorption
    Mechanical digestion of protein begins in the mouth and continues in the stomach and small intestine. Chemical digestion of protein begins in the stomach and ends in the small intestine. The body recycles amino acids to make more proteins.
  • 6.5: Protein’s Functions in the Body
    The many shapes and sizes of proteins allow them to perform a vast array of functions, including: acting as enzymes and hormones, and providing for fluid and acid-base balance, transport, protection, wound healing and tissue regeneration, and energy production. Without adequate intake of protein containing all the essential amino acids, all protein functions will be impaired.
  • 6.6: Diseases Involving Proteins
    Protein deficiency syndromes are a leading cause of death in children under the age of five in poor, underdeveloped countries. Protein deficiency can cause swelling, fatigue, skin problems, irritability, muscle wasting, and eventual death from infection. The long-term health consequences of high-protein diets have not been adequately studied.
  • 6.7: Proteins, Diet, and Personal Choices
    The RDA set for protein for adults is 0.8 grams per kilogram of body weight and represents the amount of protein in the diet required to balance the protein that is used up by the body and that is excreted. The protein foods group consists of foods made from meat, seafood, poultry, eggs, soy, beans, peas, and seeds. By determining a food’s amino acid content and the amount of protein that is actually digested and absorbed we can determine that food’s protein quality.
  • 6.E: Proteins (Exercises)
    Exercises to accompany the Zimmerman Textmap for Chapter 6 "Proteins."