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Chapter 4 – The Carbohydrates: Sugars, Starches, and Fibers
Learning Objectives
After completing Chapter 4, the student will be able to:
4.1 Identify the monosaccharides, disaccharides, and polysaccharides common in nutrition by their chemical
structures and major food sources.
a. Classify carbohydrates as mono-, di-, or polysaccharides.
b. Explain the two major types of dietary fibers and their uses in the body.
4.2 Summarize carbohydrate digestion and absorption.
4.3 Explain how the body maintains its blood glucose concentration and what happens when blood glucose
rises too high or falls too low.
4.4 Describe how added sugars can contribute to health problems.
4.5 Identify the health benefits of, and recommendations for, starches and fibers.
a. Identify the health benefits of a diet rich in starch and fiber.
b. Identify the Daily Value and DRI for fiber and methods to increase fiber in the diet.
4.6 Summarize the key scientific evidence behind some of the current controversies surrounding carbohydrates
and their kcalories.
a. Discuss the role of carbohydrates in weight gain and in weight-loss diets.
Assignments and Other Instructional Materials
The following ready-to–use assignments are available in this chapter of the instructor’s manual:
• Worksheet 4-2: Glycemic Index and Glycemic Load
• Worksheet 4-3: Hidden Sugars—What Is Your Sugar IQ?
• Worksheet 4-4: Check Your Carbohydrate Choices2
• New! Worksheet 4-5: Chapter 4 Crossword Puzzle3
• New! Critical thinking questions with answers
1 Worksheets 4-1, 4-2, and 4-3 contributed by Daryle Wane.
2 Worksheet 4-4 and Handouts 4-1, 4-2, 4-4, and 4-5 contributed by Sharon Rady Rolfes
3 Contributed by Carrie King.
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• Handout 4-4: How to Use the Exchange System to Estimate Carbohydrate
• Handout 4-5: Fibers
Lecture Presentation Outline4
Key to instructor resource annotations (shown to the right of or below outline topics):
I. The Chemist’s View of Carbohydrates (Figure 4-1) 10e TRA 31; IM WS 4-1
A. Monosaccharides – Define and provide examples, including: 10e TRA 32, 33
B. Disaccharides – Define, explain the processes of condensation and hydrolysis, and provide examples of
disaccharides 10e TRA 34, 35
1. Condensation (Figure 4-4)
C. Polysaccharides – Define and provide examples, including: 12e TRA 6
1. Glycogen
a. Storage form of glucose in the body
b. Provides a rapid release of energy when needed
2. Starches (Figure 4–6)
3. Fibers Website HN 4-3, 4-5
a. Soluble fibers
b. Insoluble fibers
II. Digestion and Absorption of Carbohydrates
A. Carbohydrate Digestion – Describe the process of carbohydrate digestion in the following anatomical areas
(Figure 4-8):
1. In the Mouth – Amylase
B. Carbohydrate Absorption – Describe the process of carbohydrate absorption (Figure 4–9) 13e TRA 8
1. Active transport
2. Facilitated diffusion
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C. Lactose Intolerance – Discuss the condition, including
1. Symptoms
III. Glucose in the Body
A. A Preview of Carbohydrate Metabolism
1. Storing Glucose as Glycogen – Explain how and where the body stores glucose as glycogen
B. The Constancy of Blood Glucose – Explain the regulation of blood glucose (Figure 4-10)
including: 12e TRA 7
1. Maintaining Glucose Homeostasis – Describe the symptoms of low and high blood glucose
2. The Regulating Hormones – Explain how insulin, glucagon, and epinephrine are involved in blood
glucose
3. Balancing within the Normal Range – Describe how food intake affects the maintenance of glucose
within the normal range IM CA 4-1
IV. Health Effects and Recommended Intakes of Sugars IM CS 4-1
A. Health Effects of Sugars – Discuss the health effects of sugars, including their influence on:
1. Obesity and Chronic Diseases
C. Alternative Sweeteners – Discuss the use of these products, including: IM HN 4-2
1. Artificial Sweeteners
2. Stevia—An Herbal Sweetener
3. Sugar Alcohols
V. Health Effects and Recommended Intakes of Starch and Fibers
A. Health Effects of Starch and Fibers – Explain the role of fiber in
1. Heart Disease – Heart disease and stroke
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B. Recommended Intakes of Starch and Fibers
1. RDA for carbohydrate is 130 g per day; AMDR is 45%-65% of energy intake
2. Daily Value for total carbohydrate is 300 grams per day
3. Dietary Guidelines encourage a variety of whole grains, vegetables, fruits, and legumes daily
5. Fiber IM CA 4-3
a. FDA sets the Daily Value at 25 grams for a 2,000-kcalorie diet
b. DRI at 14 g per 1000 kcalorie intake (28 grams for a 2,000-kcalorie diet)
VI. Highlight: Carbs, kCalories, and Controversies
A. Carbohydrates’ kCalorie Contributions 12e TRA 8, 9
1. Blamed for increases in obesity
2. As carbohydrate intake increases, body weight decreases
3. Weight loss is due to kcalorie restriction
Case Studies5
Case Study 4-1: Sweeteners and kCalorie Control
Frank P. is a 48-year-old landscape architect who is concerned about his recent weight gain. He is 69 inches tall and
weighs 202 pounds. His usual weight is 190 pounds. Frank reports that—due to his busy schedule—he often skips
breakfast or stops for a donut and coffee with cream and sugar on his way to work in the morning. He frequently
eats out with clients for lunch and eats dinner at home with his wife most evenings. His favorite nighttime snack is
ice cream. He reports sometimes feeling tired and hungry during his work day, which he says is relieved by eating a
candy bar or drinking a canned cola beverage. He reports no food intolerances, although he states he avoids products
which contain high-fructose corn syrup and prefers to use products sweetened with sugar.
1. Which foods are sources of added sugars in Frank’s diet?
2. What strategies could help Frank decrease his intake of calories from added sugars?
3. If Frank wants to lose weight, why is it important for him to choose high-fiber carbohydrate foods in his diet?
4. How might alternative sweeteners benefit Frank’s weight loss efforts? How would you advise him on the safe
use of these sweeteners?
5. What advice would you give Frank on his use of sugar versus high-fructose corn syrup?
6. Based on his lifestyle pattern, devise a one-day meal plan for Frank that is lower in added sugar and calories.
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Answer Key
1. Donut, sugar in coffee, candy, sodas, ice cream.
Case Study 4-2: Increasing Dietary Fiber
Erin C. is a single woman who has been advised by her doctor to increase her intake of dietary fiber due to frequent
constipation. Her intake over the past 24 hours includes: 8 oz. orange juice, 2 cups coffee with cream, 2 slices
whole-wheat toast with margarine and jam, cheeseburger, french fries, diet soda, baked chicken, mashed potatoes,
lettuce salad with dressing, and iced tea with sugar.
1. Using the general information in Table 4–6, what are some potential sources of fiber in Erin’s diet? How much
fiber do you estimate she gets from these foods?
2. Assuming Erin eats approximately 2000 calories per day, what is her recommended daily intake of dietary fiber
based on the DRI?
3. Explain how Erin might use the “Three are key” message to help her remember to add more whole grains to her
diet.
4. What are some strategies that can help Erin identify high-fiber whole-grain foods when she shops?
5. Adjust Erin’s current daily menu to show how she can get her recommended daily intake of fiber and whole
grains.
6. What precautions will be important for Erin to know about and practice as she begins to increase her intake of
dietary fiber?
Answer Key
1. 2 slices wheat toast (1 to 2 grams per slice = 4 grams); lettuce salad (2 grams); mashed potatoes (1-2 grams if
skin is left on).
Suggested Classroom Activities
An excellent way to begin this chapter is with a discussion of the brain’s dependence on glucose and the body’s
regulation of it. The concepts are new to the majority of beginning students, complex enough to be challenging but
simple enough to grasp, and of great personal interest.
doesn’t “work,” explain what you would expect to see, and why. Criticize the demonstration as unscientific (it’s not
blind, there may be bias); but point out that it at least illustrates that a balanced breakfast can influence a morning’s
performance, while the many deviations from the average show that a multitude of other factors are working, too.
This exercise may help students remember that dietary protein influences blood glucose regulation—a first stone in
the foundation for understanding metabolism.
Classroom Activity 4-3: Fiber Content of Over-the-Counter Fiber Supplements
Key concept: Fiber sources Class size: Any
Instructions: Fiber supplements are marketed as providing substantial amounts of fiber. Instruct students to go to the
grocery or drug store and record the following regarding the fiber supplements they locate: name of supplement,
cost of supplement, recommended daily dose, fiber content of suggested dose, and the percent of the DV for fiber
that each provides. Discuss in class and generate suggestions for more effective, enjoyable, and economical choices.
Classroom Activity 4-4: Carbohydrates at Breakfast (Meal Comparison)6
Key concept: Applying carbohydrate recommendations Class size: Any
Instructions: Present the two breakfast meal plans below to students and use the discussion questions to prompt them
to evaluate the plans.
Discussion questions:
1. What types of simple carbohydrates are included in breakfast #1? Are these “bad sugars”?
2. Which breakfast provides better nutrient density?
3. What kinds of health benefits could breakfast #1 provide? Breakfast #2?
4. What are the various recommended intakes for fiber? Which breakfast would help you meet these
recommendations?
5. Does breakfast #1 have a high glycemic index?
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Answer key:
1. Lactose in the milk, fructose in the berries, sucrose in the bran cereal. No, the foods containing these sugars are
important food-based carbohydrate sources that provide nutrition for health and activities of daily living (i.e.,
water-soluble vitamins, minerals, energy).
Nutrient composition of meals for instructor reference:
Key: Cal = kcalories, CC = complex carbohydrates (grams), SC = simple carbohydrates (grams), Fib = fiber (grams)
Classroom Activity 4-5: Scheduled Interruption: Think/Pair/Share
Objective: Reflection on content Class size: Any
Instructions: Examination of student attention levels throughout class indicate that students’ attention levels are the
highest during the first five minutes of class, then levels slowly decline throughout a lecture. To enhance students’
attentiveness, teaching authorities suggest scheduled interruptions. One planned interruption is think, pair, share.
The purpose of this activity is to encourage the participation of all students, especially those who are quiet. Pose a
statement, problem, or situation. Instruct students to quietly write their comments including their thoughts and
feelings regarding this topic. Next, pair students with a partner and instruct them to share their comments. Circulate
while students are talking. After they have shared with their partner, ask for comments to be shared with the entire
class.
How To “Try It!” Activity Answer Key
How to Reduce the Intake of Added Sugars
Stonyfield strawberry vs. plain low-fat yogurt: The strawberry yogurt provides 200 kcal/cup, and the second item
on the ingredients list (after cultured milk) is added sugar. The plain yogurt provides 120 kcal/cup (40% less than
the flavored) and no added sugars; its sugars are all the naturally occurring ones from the cultured milk. Kellogg’s
Frosted Flakes vs. corn flakes: The frosted corn flakes provide 147 kcal/cup and 11 g sugars/cup. The corn flakes
provide 100 kcal/cup (32% less than the frosted) and 2 g sugars/cup (9 fewer g). The second and fourth ingredients
in both regular and frosted corn flakes are added sweeteners: sugar and high-fructose corn syrup. Thus, the two
varieties contain the same added sugars, but the frosted type contains 5.5 times as much of them. Sunkist orange
soda vs. Florida’s Natural Premium orange juice: The soda provides 127 kcal/cup and 33 g sugars/cup, all of
which come from high-fructose corn syrup, the second ingredient listed (after carbonated water). The juice provides
slightly less (-13%) energy at 110 kcal/cup, but importantly, all 22 g of its sugars are naturally occurring, since
orange juice is the sole ingredient.
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Study Card 4 Answer Key
1. In a condensation reaction, two compounds are joined together to make a larger one, and a molecule of water is
2. Polysaccharides contain many glucose units and, in some cases, a few other monosaccharides strung together.
Glycogen is made of many glucose molecules linked together in highly branched chains. Starch consists of
6. In the mouth, thoroughly chewing high-fiber foods slows eating and stimulates the flow of saliva. Fibers are not
digested, but because they linger in the stomach, they delay gastric emptying, thereby providing a feeling of
7. Lactose intolerance is a condition that results from the inability to digest the milk sugar lactose. (Lactose
intolerance differs from milk allergy, which is caused by an immune reaction to the protein in milk.) It is
10. Within the body, ingested glucose may be used for energy by the cells or stored as glycogen (in the muscles and
liver) and/or fat (in fat cells). Carbohydrate’s protein-sparing action is its ability to prevent the body from
14. Because added sugars deliver kcalories, but few or no nutrients or fiber, the Dietary Guidelines for Americans
urge consumers to “reduce the intake of kcalories from added sugars.” The DRI suggests that added sugars
15. The benefits of using alternative sweeteners include reductions in intakes of total kcal and added sugars when
Critical Thinking Questions7
1. Lactose intolerance and sensitivity appears to be a growing phenomenon in this country. Even though many
people limit or avoid dairy products in their diets, they seem to still suffer from symptoms. What would account
for this fact? What characteristics may predispose individuals to become lactose intolerant and/or sensitive?
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What dietary options that would be feasible for individuals who are lactose intolerant/sensitive allow them to
meet critical nutrient needs such as calcium, riboflavin, and vitamin D?
2. There are a lot of alternative sweeteners being marketed to consumers. What methods can be used to make an
informed choice as to which alternative sweetener is the best for individual use?
3. The increased intake of carbohydrates is associated with an increased potential for development of obesity in
the United States. What food product additives in the American diet are most likely to promote weight gain?
4. Fiber plays a significant role in helping an individual maintain nutritional health and well-being. If a friend
seeks to increase dietary fiber in his/her diet, what recommendations would you make to ensure that the friend’s
dietary fiber intake is adequate and beneficial?
5. Explain how the “three are key” message can be used to promote healthy carbohydrate consumption in the
American diet.
Answer Key
1. Lactose is a component part of many processed foods and/or non-dairy food items and as such it is important to
read all food labels, looking for milk, milk solids, whey, and casein. Lactose can also be used as a binder
preparation in certain medications, both prescription and over the counter. Thus, it is important to research both
food and drug preparations and their constituent components if one has lactose intolerance and/or lactose
2. Many alternative sweeteners can be classified as non-nutritive sweeteners. The majority of those on the market
do not provide energy (calories) to the diet. Sugar alcohols do provide energy and are considered nutritive
sweeteners. When considering which type of alternative sweetener to use, it is important to consider the relative
3. Clinical research has shown that consumption of sugar-enhanced beverages such as fruit juices and soda
account for a sizeable increase in caloric intake for many individuals. As these beverages are easily accessible
4. Dietary fiber helps to regulate intestinal health and promote healthy elimination patterns. In addition, dietary
fibers (whole grains and soluble fiber) provide protection against heart disease, diabetes, and certain cancers
and assist with weight management. If someone seeks to add dietary fiber to his/her diet, he/she must also
5. Clinical research has demonstrated that the increased use of whole-grain foods contributes to a healthier diet
pattern. Certain foods are further identified with whole grain stamps on their packaging in order to help
IM Worksheet Answer Key
Worksheet 4-1: Carbohydrate Basics (Internet Exercise)
1. b
4. a
Worksheet 4-2: Glycemic Index and Glycemic Load
Food
GI
Net Carbs
GL
GI Level
Worksheet 4-3: Hidden Sugars—What Is Your Sugar IQ?
Worksheet 4-5: Chapter 4 Crossword Puzzle
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Worksheet 4-1: Carbohydrate Basics (Internet Exercise)
On the website, click on Carbohydrates to answer questions 1 through 3.
1. “Bad carbs” and “good carbs” are terms that are used in the Dietary Guidelines for Americans.
2. An example of a food rich in insoluble fiber is oatmeal.
3. Match the term with the best explanation.
a. Complex carbohydrate
b. Simple carbohydrate
c. Added sugar
_____ Naturally occurring sugars found in foods
_____ High-fructose corn syrup
_____ Starch
4. Which of the following are considered to be basic building block elements of carbohydrates?
a. Carbon, hydrogen, and oxygen
b. Glucose, dextrose, and sucrose
c. Carbon, hydrogen, and nitrogen
d. Carbon and oxygen
5. Fructose has a strong effect on blood sugar.
6. Inclusion of whole grains in one’s dietary pattern will lead to improved health.