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Lecture
Outline
Chapter 5
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Carbohydrates
Chapter 5
Insert photo from 1st page of
chapter
Chapter Learning Outcomes
1. Identify the major carbohydrates in
human diets and their major food
sources.
2. Recognize chemical and common
names of nutritive sweeteners and
identify common alternative
sweeteners.
3. List the functions of carbohydrates in
the body and roles of carbohydrates in
health.
Chapter Learning Outcomes
(continued)
4. Describe how the body digests carbohydrates
and regulates blood glucose.
5. Discuss differences between type 1 and type
2 diabetes and list common signs and
symptoms of each disorder.
6. Identify risk factors for type 2 diabetes and
measures that may prevent the disease.
7. Explain the health benefits of soluble and
insoluble fiber and identify rich food
sources of these types of fiber.
Chapter Learning Outcomes
(continued)
8. Define lactose intolerance, explain why
the condition occurs, and discuss
dietary measures that will reduce signs
and symptoms of the disorder.
Quiz Yourself
True or False

1. Compared to table sugar, honey is a natural and
far more nutritious sweetener. T F
2. Ounce per ounce, sugar provides more energy
than starch. T F
3. Eating a high-fiber diet can improve the
functioning of your large intestine and reduce
your blood cholesterol levels. T F
4. The average American consumes 40% to 50% of
his/her energy intake as refined sugars. T F
5. The results of clinical studies indicate that eating
too much sugar makes children hyperactive.
T F
How Did You Do?

1. False Compared to table sugar, honey is not a
significantly more nutritious sweetener.
2. False Ounce per ounce, sugar provides the
same amount of energy as starch.
3. True Eating a high-fiber diet can improve the
functioning of your large intestine and reduce
your blood cholesterol levels.
4. False The average American consumes about
50% of his/her energy intake from all
carbohydrates.
5. False The results of clinical studies do not
indicate that sugar makes children hyperactive.
What are Carbohydrates?
Carbohydrates are:
- Major source of energy
- Plants use CO2, H2O, and energy from the sun
to make carbohydrates
- Often identified by chemical name ending in
“-ose”
How Carbohydrates Are Made
Insert Figure 5.1
Plants use the sun’s
energy to combine
carbon, oxygen, and
hydrogen to form
carbohydrates.
Simple Carbohydrates: Sugars
Monosaccharide
mono= one
saccharide= sugar
Disaccharide
di= two
saccharide= sugar
Monosaccharides
Glucose
- Primary energy source for
cells
- “dextrose”
Fructose
- “Fruit sugar” or “levulose”
Galactose
- Part of “milk sugar”
(lactose)
• Insert Figure 5.2
Disaccharides
Maltose
glucose + glucose
Sucrose
glucose + fructose
Lactose
glucose + galactose
• Insert figure 5.3
Sucrose
• Table sugar:
– Almost 100% sucrose
– Made from sugar cane or sugar beets
– Refinement strips away small amounts of
vitamins and minerals naturally in cane and
beets
• Occurs naturally in honey, maple syrup,
carrots, and fruits such as pineapples
Nutritional
Comparison of
Selected
Sweeteners
• Insert table 5.1
• Insert photos of sugar
& honey from page
113.
Names for Sugars
Insert table 5.2
How Much Added Sugar Is In That Food?
Insert table 5.3
Nutritive and Alternative Sweeteners
Nutritive sweeteners
– Contribute energy to foods
• Provide 4 kcal/g
– Added sugars
• Nutritive sweeteners, such as sucrose and
high fructose corn syrup, added during processing or
preparation
– Alternative Nutritive Sweeteners
• Sorbitol, xylitol, mannitol
– Sweeten without providing much kcal
– Do not promote dental decay
Non-nutritive “Artificial”
Sweeteners
• Intensely-sweet synthetic compounds that sweeten
foods without providing kcal/serving
• FDA approved:
– Saccharin, aspartame, acesulfame-K, sucralose, and
neotame
• Saccharin used for >100 yrs
– Most scientific evidence supports its safety
• Cyclamates banned in the U.S. since 1970
– Despite being determined as safe by panel of experts from
FDA and NAS
Comparing Artificial Sweeteners
Insert Table 5.4
Aspartame
Brand names include
Nutrasweet and Equal
Consists of phenylalanine and
aspartic acid
People with phenylketonuria
must avoid aspartame.
Insert Figure 5.4
Stevia
• Herbal extract from
South American shrub
– used to sweeten foods
in Japan and South
America
• May be sold as dietary
supplement in U.S.
• Not FDA approved as
a food additive
Complex Carbohydrates
Polysaccharides
• Contain >10
monosaccharides
bonded together
• Storage form of
carbohydrate in plants
and animals
• Structural component
of plants in stems and
leaves
Starch and Glycogen
Starch
 Storage form of carbohydrate in
plants
 In seeds, roots, and tubers
 Modified starches (maltodextrin,
dextrin, and glucose polymers)
Glycogen
- Storage form of carbohydrate
in humans and other animals
- Stored primarily in liver and
muscles
Insert Figure 5.5
Most forms of fiber are complex carbohydrates
Fiber
the human body cannot digest.
• Soluble
• Insoluble
Insert Table 5.5
Dietary Fiber Content of Common Foods
What’s a Whole Grain?
Insert Figure 5.6
• The intact, ground,
cracked, or flaked
seeds of cereal
grains
• Must contain:
– Fiber-rich bran
– Starchy endosperm
– Oily germ
What
Happens to
Carbohydrates
in Your
Body?
• Insert Table 5.6
Maintaining Blood Glucose Levels
Insulin and Glucagon
Key hormones that maintain normal blood glucose levels
Insert Figure 5.9
Maintaining Blood Glucose Levels
Hormone
When Secreted
Action on Glucose
Insulin
 Blood glucose
Uptake by cells
Glucagon
 Blood glucose
Glycogen breakdown
 Synthesis of glucose
Insert Figure 5.9
Effects of Insulin
• Enables glucose to enter cells
• Enhances production/storage of:
– Fat
– Glycogen
– Protein
• Decreases hunger
What Happens When You Don’t Eat
Glucagon is released and stimulates:
- Glycogenolysis
Glycogen breakdown releasing
glucose to the blood
- Lypolysis
Breakdown of triglycerides (fat) for
energy
Glucose for
Energy
• Cells use oxygen to
release energy stored
in glucose’s chemical
bonds.
• Carbon dioxide and
water are formed in
the process.
Insert Figure 5.10
Ketones and Ketosis
Ketones
• Form as a result of incomplete fat breakdown
– Poorly controlled diabetes
– Fasting or starving
– Low-carbohydrate, high-protein diet (e.g., Atkins)
• Used by certain cells for energy
Ketosis
• Condition that occurs with very high blood
ketones
• Unconsciousness and death may occur
Carbohydrate Consumption Patterns
• Average American
~16% kcal (~20 tsp)
from added sugars
• Dietary Guidelines
recommend limiting
added sugar intake to
4 tsp/day for 2000 kcal
diet.
• Insert Figure 5.11
Reducing Your Intake of Refined
Carbohydrates
• Sources of refined carbohydrates:
–
–
–
–
Regular soft drinks
Cookies
Candy
Chips
• Most processed foods
• Suggested substitutes:
–
–
–
–
Plain water
Whole grains and nuts
Fresh fruits and vegetables
Plain yogurt sweetened with fresh fruit, dried
fruits
Understanding
Nutrition Labeling:
Carbohydrate and
Fiber
Information about total
carbohydrates, sugar,
and fiber content in a
serving of food
• Insert Figure
5.12
Carbohydrates and Health
Frequently Asked Questions:
•
•
•
•
•
•
•
•
Are all high-carbohydrate foods fattening?
What is diabetes?
What causes hypoglycemia?
Is belly fat linked to metabolic syndrome?
How do carbohydrates contribute to tooth decay?
Why do some people have lactose intolerance?
Does sugar cause hyperactivity?
Do we really need to eat more fiber?
Are Carbohydrates Fattening?
It may depend on the type of
carbohydrate…
Probably “fattening” :
• Added sugars
• Refined starches
• High-fructose corn syrup
Insert photo
Of sweets
from page
125
Healthier choices:
• Fiber-rich foods (e.g., fruits, vegetables, and unrefined
grains)
What is Diabetes?
Diabetes mellitus
• Group of serious chronic diseases
characterized by abnormal glucose, fat, and
protein metabolism
– Type 1 diabetes
• Autoimmune disease
• Beta cells stop making insulin
– Type 2 diabetes
• Most common type
• Insulin resistant cells
Insert Table 5.7
Signs and
Symptoms of
Diabetes
Mellitus
• Insert Table 5.8
Use the American Diabetes
Association’s questionnaire
to assess your risk of
type 2 diabetes.
www.diabetes.org/risk-test/text-version.jsp
Controlling Diabetes
1. Maintenance of normal or near
normal blood glucose levels
- Daily self-testing of blood glucose
- Periodic measurement of glycosylated
hemoglobin (hemoglobin A1c)
2. Maintain healthy body weight
3. Follow special diet
4. Obtain regular physical activity
What Is the Glycemic Index and
Glycemic Load?
• Glycemic index (GI) and Glycemic Load (GL)
– Standard values that indicate the body’s
insulin response to a carbohydratecontaining food
• Low GI foods may promote satiety
• High GI foods may contribute to hyperinsulinemia.
Can Diabetes Be Prevented?
• Type 1 probably cannot be prevented.
• Risk for developing Type 2 can be
reduced.
How to reduce the risk?
»Avoid excess body fat
»Exercise daily
»Follow a “prudent diet”
Prudent Diet vs. Western Diet
• Insert the image from
page 129
What is Hypoglycemia?
Hypoglycemia
- Abnormally low blood glucose levels
Fasting blood glucose < 70 mg/dl (healthy person)
- Blood glucose level is too low to provide cells adequate
energy.
- Certain signs and symptoms occur
- True hypoglycemia is rare in non-diabetics
Reactive hypoglycemia
- In some people, blood glucose drops after eating highly
refined carbohydrates.
- Pancreas responds by secreting excess insulin
Metabolic Syndrome
• Seen in ¼ of adult Americans
• Characterized by having >3 of these
signs:
• Large waist circumference
• Hypertension
•  blood triglycerides
•  blood cholesterol
•  fasting blood glucose
Signs of Metabolic Syndrome
Insert Table 5.9
Tooth Decay
• Linked to high-carbohydrate diet,
especially sticky simple sugars that
remain on teeth (residue)
• Bacteria in mouth 
• Use carbohydrate in residue for energy
• Produce acid by-products of metabolism
• Acid damages tooth enamel
• Damaged enamel allows
decay (cavity forms)
Lactose Intolerance
• Inability to digest lactose
• Caused by inadequate lactase
– Affects ~30 to 50 million Americans
– Very common in people of African, Asian, or Eastern
European descent
• Bacteria in the large intestine break down
lactose, resulting in:
– intestinal cramps, bloating, gas, and
diarrhea
Low-Lactose Milk Products
Insert yogurt cartons
from page 131
In the process of making yogurt
and hard cheeses, lactose is
converted to lactic acid or
removed.
Insert Fig. 5.14
Lactase-treated milk does not
contain lactose. The enzyme
breaks down the disaccharide
to glucose and galactose
Does Sugar Cause Hyperactivity
Results of scientific
studies do not
indicate that sugar
Increases children’s
physical activity
level, causes
ADHD, or negatively
affects behavior.
• Insert photo of girl
with lollypop from
page 132
Fiber and Health
Fiber and the
Digestive Tract
• Low fiber intake is linked to
constipation and straining
to expel feces.
• Pressure on large intestine
(colon) may result in
diverticula formation.
• Diverticula — abnormal
tiny sacks that form in wall
of colon.
• Insert figure 5.15
Chapter 5 Highlight
Glycemic Index and Glycemic Load
• Glycemic Index (GI) — method of
classifying carbohydrate-rich food by
comparing the rise in blood glucose after
eating either 50 g of glucose or white
bread
• Glycemic Load (GL) — determined by
grams of carbohydrate in a serving of food
multiplied by the food’s glycemic index
GI & GL
of
Selected
CHORich
Foods
Criticism of GI & GL
• Some nutrition scientists do not think GI
and GL are useful for menu planning.
• GI and GL values for a particular food may
vary.
– When food is grown
– Degree of ripeness
– Extent of processing
– Other components in a meal can modify
effects on blood glucose level