More Related Content
Similar to Chapter 5 - Protein
Similar to Chapter 5 - Protein (20)
Chapter 5 - Protein
- 1. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
ProteinChapter 5
- 2. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Introduction
• Proteins are “of prime importance”
– Versatile roles: needed for muscle
contraction, blood clotting, vision, fighting
infections, building new tissue, etc.
- 3. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
The Chemist’s View of Proteins
• Atoms comprising protein
– Carbon, hydrogen, oxygen, and nitrogen
• Amino: contains nitrogen
• About 20 different amino acids in proteins
• Amino acids bond together
– Dipeptide
– Tripeptide
– Polypeptide
- 4. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
The Chemist’s View of Proteins
(cont’d.)
• What determines the shape of polypeptide
chains?
– Different shapes: enable proteins to perform
different tasks in the body
- 8. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
The Chemist’s View of Proteins
(cont’d.)
• Nonessential amino acids
– The body can make them for itself
• Essential amino acids
– Must be obtained in foods
• What is a conditionally essential amino
acid?
- 9. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein Digestion and Absorption
Long peptide chains + enzymes
Short peptides + enzymes
Tripeptides and dipeptides + enzymes
Amino acids
- 10. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein Turnover and Nitrogen
Balance
• Protein turnover
– Continual process in which proteins are made
and broken down
– What are some specific examples?
– Amino acids needed each day: support new
growth and maintenance of cells
• Nitrogen balance (nitrogen equilibrium)
– Nitrogen intake equals nitrogen output
- 11. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Roles of Body Proteins
• Structural components
– Muscle, bones, teeth, tendons, cartilage,
blood vessels, etc.
• Enzymes
– Catalysts essential to all life processes
• Some enzymes: break food proteins into amino
acids
• Other enzymes: build long chains of amino acids
- 13. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Roles of Body Proteins (cont’d.)
• Transporters
– Move substances around the body
• Protein hemoglobin: carries oxygen
• Lipoproteins: transport lipids
• Regulators of fluid and electrolyte balance
– Maintain necessary amounts and types of
fluid and minerals in each compartment of the
body fluids
- 15. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Roles of Body Proteins (cont’d.)
• Regulators of acid-base balance
– Maintain the balance between acids and
bases within the body’s fluids
– What are the conditions of acidosis and
alkalosis?
• Antibodies
– Produced when body detects antigens
– What is immunity?
- 17. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Roles of Body Proteins (cont’d.)
• Hormones
– Some hormones: comprised of proteins
• Source of energy and glucose
– When glucose or fatty acids are limited
• Functions of proteins (Table 5-2)
- 18. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein and Health
• Protein deficiency
– Slow growth in children, impaired brain and
kidney function, weakened immune defenses,
and impaired nutrient absorption
– Conditions
• Protein-energy malnutrition (PEM)
• Severe acute malnutrition (SAM): kwashiorkor and
marasmus
• Chronic malnutrition
- 20. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein and Health (cont’d.)
• Protein deficiency
– What are ways to prevent and treat
malnutrition?
• Protein excess
– Heart disease
– Kidney disease
• Protein and amino acid supplements
– Unsupported by scientific studies
- 21. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein and Health (cont’d.)
• Protein recommendations and intakes
– RDA
• Adult: 0.8 gram per kilogram (2.2 pounds) of
healthy body weight
– DRI
• Men: 10 to 35 percent of kcalories
• Women, children, and elderly: 13 to 15 percent
kcalories
- 22. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein in Foods
• High-quality proteins
– Provide adequate amounts of all of the
essential amino acids
– Influenced by:
• Protein digestibility
• Amino acid composition
– Limiting amino acid: essential amino acid
• Available in the shortest supply relative to the
amount needed to support protein synthesis
- 23. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein in Foods (cont’d.)
• High-quality proteins
– Generally derived from animal foods
– Soy protein
• Complementary proteins
– Two protein-rich foods combined to obtain all
the essential amino acids in amounts
sufficient to support health
- 27. Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
Protein in Foods (cont’d.)
• Protein sparing
– Carbohydrate and fat: allow amino acids to be
used to build body proteins
• Absence of carbohydrate and fat
– Body will use protein to meet energy needs
• Protein on food labels
– % Daily Value: reflects quantity and quality
