Nutrition Essentials: A Personal Approach
Unit Outline
UNIT 7
PROTEINS: LIFE’S BUILDING BLOCKS
OVERVIEW
In Unit 7, students will learn about the basic chemistry and many physiological functions of proteins.
Food sources of proteins are identified and distinctions are made between essential and nonessential
amino acids. The unit describes the pathways of digestion, absorption, and metabolism of dietary
proteins, including a discussion of nitrogen balance. There are thousands of different proteins in our
body, having a wide variety of functions. Also, it is important to note what happens during the process
of protein synthesis. Students will be able to explain what happens to excess amino acids that are not
stored by muscles or other tissues in your body. In this Unit, calculating Recommended Dietary
Allowance (RDA) is demonstrated. The different types of vegetarian diets, including some that combine
plant foods with certain animal foods are identified. The author discusses why high-protein diets are
generally not recommended for healthy people, and explains the difference between a high-quality
protein and a low-quality protein, and identify foods that are rich sources of high-quality proteins. Unit 7
highlights the causes of a food allergy, identifies foods that are most likely to cause food allergies, and
list common signs or symptoms of a food allergy. Students will also learn what causes celiac disease, and
identify foods that a person with celiac disease must avoid.
LEARNING OUTCOMES
Module 7.1
1. Define all of the key terms in this module.
2. List the primary functions of proteins in the body.
3. Identify the basic structural unit of proteins.
4. Distinguish between essential and nonessential amino acids.
Module 7.2
1. Define all of the key terms in this module.
2. Explain what happens to proteins as they undergo digestion and absorption in the human
digestive tract.
3. Explain how cells make proteins.
4. Describe what happens to excess amino acids.
5. Calculate your Recommended Dietary Allowance (RDA) for protein based on your body weight.
Module 7.3
1. Define all of the key terms in this module.
2. Identify foods that are legumes.
3. Explain the difference between a high-quality protein and a low-quality protein, and identify
foods that are rich sources of high-quality proteins.
4. Plan nutritious meals and snacks that reduce animal protein intake.
5. Develop strategies for reducing your intake of animal protein without sacrificing protein quality.
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manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Nutrition Essentials: A Personal Approach
Unit Outline
Module 7.4
1. Define all of the key terms in this module.
2. Distinguish among the various types of vegetarianism.
3. Discuss the pros and cons of vegetarian diets.
UNIT OUTLINE
I. What are Proteins? (Module 7.1)
A. Introduction
1. Proteins are organic nutrients that are chemically similar to lipids and carbohydrates
because they contain carbon, hydrogen, and oxygen atoms
2. Plants, animal, bacteria, and even viruses contain hundreds of proteins
B. What Roles Do Proteins Play In the Body
1. Make, maintain, and repair cells
2. Build structures
3. Produce enzymes, lubricants, and clotting compounds
4. Transport substances
5. Make antibodies
6. Make certain hormone
7. Maintain proper fluid balance and acid-base balance; accumulation of fluid in tissue
is called edema
8. Provide energy
C. What Are Amino Acids?
1. There are 20 amino acids in human proteins
a. A carbon atom that anchors a hydrogen atom
b. The amino (nitrogen-containing) group
c. The R-group
d. The acid group
D. The body can convert the carbon skeletons of certain amino acids to glucose and use
the simple sugars for energy
E. Nonessential amino acids are the group of amino acids that the body can make
F. Essential amino acids are amino acids the body can’t make or can’t make enough to
meets its needs
II. What Happens To The Protein You Eat? (Module 7.2)
A. Protein Digestion and Absorption
1. An amino acid can connect to another amino acid by a peptide bond
2. A polypeptide forms when two or more amino acids join to form chains
3. Digesting and Absorbing Proteins (EC 7.1)
a. Protein digestion begins in the stomach
b. Pepsin, an enzyme makes it easier to break apart the peptide bonds between
amino acids
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manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Nutrition Essentials: A Personal Approach
Unit Outline
c. The shortened polypeptide chains enter the small intestine, the pancreas and
absorptive cells secrete protein-splitting enzymes called proteases
d. Enzymes with the border of absorptive cells digest the simple polypeptides into
amino acids
B. Using Amino Acids to Build Proteins
1. A specific protein can be identified by the kinds of amino acids it contains and the
order in which they are configured
2. A summary of protein digestion, absorption, and elimination
a. stomach – proteins undergo partial digestion by pepsin
b. small intestine – further digestion occurs as the pancreas and intestinal cells
secrete protein-splitting enzymes
c. Small intestine cells – final digestion occurs at the absorptive cells with the
release of enzymes from microvilli
d. Liver – after being absorbed, amino acids enter a vein and travel to the liver
e. Rectum – very little dietary protein is excreted in feces
3. DNA is often referred to as the cells’ master molecule because it contains coded
instructions for making proteins
a. Sickle cell disease is an inherited disorder that primarily affects people with
African ancestry
b. In some cases, sickle cell disease is deadly
C. The Fate of Excess Protein
1. What Can Happen to Unneeded Amino Acids (EC 7.2)
a. Unnecessary amino acids are stripped of their nitrogen-containing portion
b. The carbon skeletons that remain are converted into glucose or fat, used to
make nonessential amino acids, or are metabolized for energy
2. Your urine contains most of the lost nitrogen
3. To be healthy your body needs amino acids from foods to replace the lost nitrogen
D. How Much Protein Do You Need
1. A healthy adult’s RDA for protein is 0.8 g/kg of body weight
2. The body’s need for protein increases during pregnancy, during breastfeeding, and
in periods of growth, extreme physical exertion, and recovery from serious illnesses,
blood losses, and burns
3. The average American at age two or older consumed almost 80g protein/day (2009–
2010)
4. MyPlate: Recommendations for Protein Intake
a. Your RDA for protein is based on your body weight
b. Choose lean or low-fat meat and poultry
c. Include more plant sources of protein in your diet
III. Proteins in Foods (Module 7.3)
A. Introduction
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manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Nutrition Essentials: A Personal Approach
Unit Outline
1. People often associate animal foods with protein, but beans, nuts, seeds, grains,
and certain vegetables are good sources of protein too
2. Legumes are plants that produce pods that have a single row of seeds, such as
soybeans, peas, peanuts, lentils, and beans
3. Tree nuts include walnuts, cashews, and almonds
B. Protein Quality
1. A high-quality or complete, protein contains all essential m amino acids in amounts
that support the health of your muscles and other tissues, as well as a young child’s
growth
2. A low-quality, or incomplete protein lacks or contains inadequate amounts of one
or more of the essential amino acids
3. Most plant foods aren’t sources of high-quality proteins
a. Quinoa and soy are exceptions
b. Processed soybeans are used to make a variety of nutritious foods, including soy
milk, infant formula, and meat substitutes
4. Complementary combinations are mixtures of certain plant foods that provide all
essential amino acids without adding animal proteins
5. Examples of combinations can be found in Figure 7.6
C. Stretching Your Food Dollars
1. Include only one animal source of protein in a meal and reduce its serving size
2. Replace meat with other high-quality protein sources
3. Prepare meals that contain less animal protein and more plant proteins
IV. Vegetarianism (Module 7.4)
A. Vegetarians rely heavily on plant foods and may or may not include some animal foods
in their diets
B. There are different types of vegetarian diets
1. Semivegetarian
2. Lactovegetarian
3. Ovovegetarian
4. Lactoovegetarian
5. Vegan
C. Is Vegetarianism a Healthy Lifestyle
1. Vegetarians tend to have a lower risk of obesity, type 2 diabetes, hypertension, and
certain cancers
2. Vegetarian diets provide more fiber, phytochemicals, folic acid, vitamins E, C, and
the minerals potassium and magnesium
3. Plant foods add bulk to diet without adding a lot of calories
4. Vegans can obtain adequate amounts of the essential amino acids by eating
processed soybean products and foods that combine complementary plant proteins
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manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Nutrition Essentials: A Personal Approach
Unit Outline
5. Parents should monitor vegetarian children’s diets to make sure that they meet
their protein and energy needs
6. Vegan mothers may need to provide their babies with a source of vitamin B12
7. Commercially prepared vegetarian foods are often available in the frozen food
section of supermarkets
V. Proteins and Health (Module 7.5)
A. Excess Protein Intakes
1. High-protein diets are generally not recommended for healthy individuals
2. Excess amino acids or protein intake can lead to dehydration because the kidneys
need more water dilute and eliminate the extra urea in urine
3. An athlete’s diet should supply enough calories from carbohydrate and fat to
support energy needs for increased physical activity
4. Taking protein supplements isn’t recommended for healthy persons
5. Excessive intakes of arginine and methionine can be toxic
6. People who follow high-protein diets to lose weight often report decreased feelings
of hunger and increased sense of stomach fullness after meals
B. Protein Deficiency
1. Protein deficiency is uncommon in the US
2. Undernutrition is often widespread in poor nations where populations endure
frequent crop failures or civil wars
3. Protein-energy malnutrition affects people whose diets lack adequate amounts of
protein as well as energy
4. Undernutrition during early childhood can cause permanent brain damage
C. What’s a Food Allergy?
1. A food allergy occurs when the body’s immune system reacts to one or more
harmless substances (allergens) in the food
2. Immune system cells in the small intestine recognize the food protein as a foreign
substance
3. Signs and symptoms:
1. Hives
2. Swollen or itchy lips
3. Skin flushing
4. A scaly skin rash
5. Difficulty swallowing
6. Wheezing and difficulty breathing
7. Abdominal pain, vomiting, and diarrhea
4. Sensitive people who are exposed to food allergens can develop anaphylactic shock
5. Most allergenic proteins are in cow’s milk, eggs, peanuts and tree nuts, wheat,
soybeans, fish, and shellfish
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manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Nutrition Essentials: A Personal Approach
Unit Outline
6. A food intolerance doesn’t involve the immune system, but can mimic the signs and
symptoms of food allergies
7. Sulfites, a food additive may cause negative reactions such as breathing difficulties
in some people with asthma
D. What’s Gluten?
1. Gluten is a group of related proteins in wheat, barley, and rye
2. People with celiac disease cannot tolerate foods that contain gluten
3. Celiac disease is an autoimmune disease, a chronic disease in which certain immune
system cells attack and destroy normal cells in the body
4. Signs and symptoms include
a. Abdominal bloating
b. Chronic diarrhea
c. Weight loss
5. There is no evidence that gluten-free diets are useful for people who need to lose
weight
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.