C04_PPTs_Sizer_Nutrition 5ce.pptx

Adapted from:
Carla D’Andreamatteo, MSc, RD
University of Manitoba 4-1
The Carbohydrates:
Sugars, Starch,
Glycogen, and Fibre
Chapter 4

Learning Objectives
• Describe the major types of carbohydrates, and
identify foods that are sources of carbohydrates.
• Describe the various roles of carbohydrates in
the body, and explain why avoiding dietary
carbohydrates may be ill-advised.
• Summarize how fibre differs from other
carbohydrates and how fibre may contribute to
health. 4-2

Learning Objectives
• Explain how complex carbohydrates are broken
down and absorbed in the body.
• Discuss the body's use of glucose.
• Summarize pre-diabetes and type 1 and type 2
diabetes and how they are managed.
4-3

Learning Objectives
• Identify foods that are rich in carbohydrates.
• Recognize the effects of "added sugars"
and alternative sweeteners on health.
4-4

Carbohydrates
• Carbohydrates are ideal nutrients because they:
• Help meet energy needs
• Feed the brain and nervous system
• Keep the digestive system fit
• Keep the body lean
• Complex vs. Simple carbohydrates
4-5

A Close Look at Carbohydrates
• Contain the sun’s radiant energy
• Green plants:
• Make carbohydrate through photosynthesis
• Glucose
• Plants do not use all the energy stored in their sugars
• Carbohydrate-rich foods:
• Plants
• Milk (the only animal-derived food containing
significant amounts of carbohydrate)
4-6

Figure 4-1:Carbohydrate–MainlyGlucose-
Is Made by Photosynthesis
4-7
(p. 118)

A Close Look at Simple
Carbohydrates – Sugars
• Six sugar molecules
• Monosaccharides
• Glucose, fructose, galactose
• Disaccharides
• Lactose, maltose, and sucrose
• Chemical names end in -ose
4-8

4-9
Figure 4-2:How MonosaccharidesJoin to Form
Disaccharides
(p. 119)

A Close Look at Complex
Carbohydrates- Starch and Glycogen
• Starch
• Plant’s storage form of glucose
• Packed in granules
• Glycogen
• Storage form of glucose in humans and animals
4-10

Figure 4-4:How Glucose Molecules Join to
Form Polysaccharides
4-11
(p. 121)

A Close Look at Complex
Carbohydrates- Starch and Glycogen
• Fibre
• Supporting structures of plants
• Resists digestion by human enzymes; however, some
digestive bacteria produce enzymes that can break down
some fibre
• Two fibre groupings:
• Soluble, viscous, fermentable fibres are often gummy
or add thickness to foods
• Insoluble, non-viscous, less fermentable fibres are
often tough, stringy, or gritty in foods
4-12

The Need for Carbohydrates
• Carbohydrates and weight loss:
• Carbohydrate provides fewer Calories than fat
• A moderate balanced diet based on foods high in
complex carbohydrates is likely to be lower in total
Calories than a diet based on high-fat food
• However, select nutrient-dense carbohydrates and
limit refined sugars
4-13

Recommendations Concerning
Intakes of Carbohydrates
• Total Carbohydrates
• WHO: 55-75% of total Calories from carbohydrate
• DRI: Minimum 140 g carbohydrate per day
• “Added” or “Free” Sugars
• WHO: Less than 10% of total Calories from “free
sugars”
• Heart and Stroke: Less than 10% of total Calories
from “free sugars”, ideally less than 5%
4-14

Recommendations Concerning
Intakes of Carbohydrates
• Fibre
• WHO: More than 25 g daily
• DRI:
• AI is 48 g of total fibre per day for men through age
50 and 40 g for men 51 and older
• AI is 25 g of total fibre per day for women through
age 50 and 21 g for women 51 and older
4-15

Why Do Nutrition Experts
Recommend Fibre-Rich Foods?
• Known health benefits associated with dietary
fibre intake
• Reduced risk of heart disease
• Reduced risk of diabetes
• Reduced risk of bowel disease
• Promotion of healthy body weight
4-16

Table4-2:Characteristics,Sources,andHealthEffectsof
Fibres
4-17
(p. 124)

Figure 4-4: FibreCompositionof Common Foods
4-18
(p. 121)

• Lower cholesterol and heart disease risk
• Complex carbohydrates (whole grains), legumes,
vegetables
• Soluble, viscous fibre
• Binds with cholesterol-containing bile in the
intestine and carries it out with the feces
4-19

Figure 4-5:One-WayFibrein Food May Lower
Cholesterolin the Blood
4-20
(p. 126)

• Blood glucose control
• Soluble, viscous fibres from foods trap nutrients
and delay their transit through the digestive tract,
slowing glucose absorption
• Maintenance of digestive tract health
• All kinds of fibre along with ample fluid intake
4-21

• Preventative benefits
of fibre
• constipation,
hemorrhoids,
appendicitis,
diverticulosis
• digestive tract cancers
(colon)
4-22

• Healthy weight management
• Complex carbohydrates tend to be low in fats and
added sugars, delivering less energy per bite
• Fibre creates feelings of fullness and
delays hunger
4-23

Fibre Recommendations and
Intakes
• Excessive fibre intake should be avoided
• Caution:
• Purified fibres
• Binders (chelating agents) in some fibres reduce
absorption of other nutrients
• Dehydration
4-24
DRI Recommendations
for Fibre
 Men, age 19–50, 48 g/day
 Men, age 51 and up, 40 g/day
 Women, age 19–50, 25 g/day
 Women, age 51 and up, 21 g/day
(p. 127)

ConsumerCorner:
Figure4-7:AWheatPlantandaSingleKernelofWheat
4-25
(p. 128)

ConsumerCorner:
Table 4-3: Termsthat DescribeGrain Food
4-26
(p. 128)

ConsumerCorner:
Figure4-8:NutrientsinWhole-Grain,EnrichedWhite,
&UnenrichedWhiteBread
4-27
(p. 129)

ConsumerCorner:
Table4-4:GramsofFibreinOneCup(250mL) of
CanadianFlour
4-28
(p. 129)

ConsumerCorner:
Figure 4-9: “Current”BreadLabelsCompared
4-29
(p. 130)

Table 4-6: Usefulnessof Carbohydrates
4-30
(p. 130)

From Carbohydrates to Glucose–
Digestion and Absorption
• Starch and disaccharides are broken down
• Monosaccharides for absorption
• Starch
• Begins in the mouth
• Splits starch into shorter units
• Digestion ceases in the stomach
• Digestion resumes in small intestine
• Resistant starch
4-31
(p. 132)

From Carbohydrates to Glucose–
Digestion and Absorption
• Sugars
• Split to yield free monosaccharides
• Enzymes on small intestine lining
• Travel to the liver
• Fibre
• Fermented by bacteria in the colon
• Odorous gas
• Gradually increase fibre intakes
4-32
(p. 132-134)

Figure 4-10:How Carbohydratein Food
BecomesGlucose in the Body
4-33
Copyright © 2021 by Nelson Education Ltd. (p. 133)

Why Do Some People Have
Trouble Digesting Milk?
• Ability to digest milk carbohydrates varies
• Lactase enzyme
• Made by small intestine
• Symptoms of intolerance
• Nausea, pain, diarrhea, and gas
• Nutritional consequences
• Dietary strategies
• Milk allergy
• Involves the immune system; not the same as an
intolerance
4-34

The Body’s Use of Glucose
• Basic carbohydrate unit used for energy
• Body handles glucose judiciously
• Maintains an internal supply
• Tightly controlling blood glucose concentrations
• Brain, nervous system, red blood cells
4-35

Figure 4-11:The Breakdownof Glucose
Yields Energy and CarbonDioxide
• Glucose is broken in
half
• Can reassemble
• Broken into smaller
molecules
• Irreversible
• Two pathways
4-36
(p. 135)

Splitting Glucose for Energy
• Glucose can be converted to fat
• Fat cannot be converted to glucose to feed the brain
• Dependence on protein when insufficient
carbohydrates are available
• Protein-sparing action
• Ketosis
• Shift in body’s metabolism
• Disruption of acid-base balance
• DRI minimum of digestible carbohydrate 4-37

Storing Glucose for Energy
• As blood glucose (BG) rises or drops, the
pancreas is the first organ to respond
• Rise in BG = release of the hormone insulin
• Drop in BG = release of the hormone glucagon
• The brain stores a small amount of glucose
• Emergency reserve to fuel the brain in severe glucose
deprivation
• Muscles and liver store glycogen
• Muscles conserve for their own use
• The liver is generous with its glycogen 4-38

Regulation of Blood Glucose
• Two safeguard activities:
• Replenishing liver glycogen stores
• Siphoning off of excess glucose into the liver and
into the muscles
• Blood glucose regulation depends mainly on the
hormones insulin and glucagon
4-39

Figure 4-12:Blood Glucose Regulation-
Overview
4-40
(p. 137)

The Glycemic Response
• The measurement of the elevation of blood
glucose and insulin in response to a food item
• Food score on a scale, Glycemic Index (GI), compared
with standard food, given a score of 100
• Diabetes
• Glycemic load (GL)
• A lower GL = less glucose build up and less insulin
needed
4-41
p. 138

Figure 4-14: Glycemic Index of Selected
Foods
4-42
(p. 133)

Appendix C: Diabetes Canada-
“Beyond the Basics” Chart
4-43

The Glycemic Response
• Many factors can affect glycemic index:
• Time of day of the test, body size and weight,
blood volume, and metabolic rate
• May vary from person to person
• Depends on how the food is prepared
• A food’s ripeness
• Food combinations in a meal
4-44

Handling Excess Glucose
• Once the liver and muscles have stored glycogen
to capacity, the body burns glucose for energy
instead of fat
• This results in:
• Fat being left in the bloodstream until picked up
and delivered to fatty tissue
• The liver breaking the excess glucose into small fat
fragments and storing
• The fat cells taking up glucose and converting it to
fat directly 4-45

Diabetes
• Prevalence of diabetes
• One of the top 10 killers of adults
• In Canada, an estimated 2.4 million people had
diabetes by 2016
• Common forms of diabetes
• Type 1 diabetes
• Type 2 diabetes
4-46

Table 4-7: Warning Signs of Diabetes
4-48
(p. 140)

Table 4-8: Diabetes Types 1 and 2
Compared
4-49
(p. 141)

Type 1 Diabetes
• 5 to 10 percent of cases
• Common age of occurrence
• Autoimmune disorder
• Own immune system attacks pancreas
• Lose ability to produce insulin
• External sources of insulin
• Fast-acting and long-acting forms
4-50

Type 2 Diabetes
• Predominant type of diabetes
• Lose sensitivity to insulin
• Obesity underlies many cases
• Other factors foreshadowing development of
type 2 diabetes:
• Middle age and physical inactivity
• Body fat accumulation
• Genetic inheritance
4-51

Pre-diabetes
A condition in which blood glucose levels are
higher than normal but not high enough to be
diagnosed as diabetes. It is considered a major
risk factor for future diabetes and cardiovascular
diseases.
4-52

Management of Diabetes
• Nutrition intervention
• Weight management (type 2 diabetes)
• Dietary management includes:
• Adequate nutrient intake
• Adequate fibre intake
• Moderate intake of added sugars
• Controlled in total carbohydrate
• Low in saturated fat, provides some unsaturated oils
• Adequate protein intake
4-53

Management of Diabetes
• In addition to nutrition intervention:
• Physical activity (assists with prevention and
management of diabetes)
• Improves tissue sensitivity to insulin
4-54

Hypoglycemia
• Abnormally low blood glucose
• Postprandial hypoglycemia (rare)
• Fasting hypoglycemia
• Symptoms differ depending on postprandial or
fasting hypoglycemia
• Causes
• Poorly managed diabetes
• Medications
• Alcohol abuse
• Others
4-55

Food Feature:
Finding Carbohydrates in Foods
• Whole-Grain Foods
• Low-fat and low-sugar choices
• Vegetables
• Starchy vegetables provide higher amounts of
carbohydrate (i.e., potatoes, corn)
• Fruits
• Vary in water, fibre, and sugar concentrations
• Limit juice to no more than one-third of a day’s fruit
intake
4-56

Food Feature:
Finding Carbohydrates in Foods
• Meat-based Protein Foods
• Carbohydrate: Nuts, dried beans, and legumes
• Milk- and Milk-Substitute Based Protein Foods
• High-quality protein
• Select lower fat options
• Oils and fats
• Do not contain carbohydrate
• Naturally occurring vs. added sugars
4-57

Sugar and Alternative Sweeteners: Are
They Bad for You?
4-58
(p. 150)

Controversy 4: Sugar and Alternative
Sweeteners: Are They Bad for You?
• Sugar Intake in Canada
• Canadians consumed the equivalent of 12+
teaspoons of sugar and syrup daily in 2009
• Consumption of artificial sweeteners has also
increased
• WHO suggests limiting added sugar intake to no
more than 10% of total Calorie intake each day
4-59

• Does sugar cause obesity?
• Human research shows conflicting results
• Between 1990-2000, Canadians on average grew
fatter
• Calories from fat and sugar both increased during
this same time
• Many studies do identify a rise in obesity rates as
sugar consumption rises
• Income is possibly tied to sugar consumption
• Increase in income = increase in sugar consumption 4-60

• Obesity (body fatness) is more closely related to
diabetes than diet
• High Calorie intake from added sugars
encourages gains of excess body fat, which
increases risk for obesity
• Obesity is a risk factor for type 2 diabetes
• Whole-grain foods and dietary fibre reduce the
risk for type 2 diabetes 4-61

• Does Sugar Increase Risk for Heart Disease?
• For most people, moderate sugar intakes pose
little risk of altering their blood lipids
• Some people seem genetically prone to increased
production of saturated fat in the body, in
response to dietary sugar
• High sugar intake as a predictor of heart disease
cannot be stated with certainty until further
research is accomplished
4-62

• Sugar and Behaviour
• Occasional behavioural reactions to sugar may be
possible
• Studies have failed to demonstrate any consistent
effects of sucrose on behaviour in either normal or
hyperactive children
4-63

• Sugar and Dental Caries
• Carbohydrate as sugar has been named as the
main causative factor in the formation of caries
• Starch supports bacterial growth if the bacteria are
allowed sufficient time to work on it
• Important:
• Length of time the food stays in your mouth
• Food’s composition
• How sticky the food is
• How often you eat the food
• Whether you brush your teeth soon afterwards 4-64

• Sugar Alcohols
• Sugar alcohols evoke a low glycemic response
• Slow absorption by the body and into the
bloodstream
• Several side effects when ingesting large
quantities
• “Laxative effect”
• Benefit
• Do not contribute to dental caries 4-65

• Evidence Concerning Artificial Sweeteners
• Do not contribute to dental caries
• Calorie-free
• All substances are toxic if consumed in high-
enough doses
• Personal strategies for using artificial
sweeteners:
• Moderate intakes of artificial sweeteners pose no
health risks for most people 4-66

4-67
p. 156

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