Download Chapter 4 Carbohydrates: Sugars, Starches

Chapter 4
Carbohydrates:
Sugars, Starches,
and Fiber
Slide Show developed by:
Richard C. Krejci, Ph.D.
Professor of Public Health
Columbia College 9.30.15
Objectives for Chapter 4
1. Compare and contrast the major types of
carbohydrates: monosaccharides, disaccharides, and
polysaccharides.
2. List the functions of carbohydrates in the body.
3. Describe the differences between insoluble and soluble
fiber and their role in promoting health.
4. Explain the process of digesting and absorbing dietary
carbohydrates.
5. Explain how the body regulates blood sugar levels, and
the hormones involved in the process.
Objectives for Chapter 4
6. Describe the guidelines for carbohydrate intake,
including the AMDR for carbohydrates, the DRI for fiber,
and the recommendation for consuming simple sugars.
7. Identify healthy food sources for each type of
carbohydrate.
8. Describe the potential health implications of consuming
too much or too little added sugar in the diet.
9. Define type 1 and type 2 diabetes and describe how
diabetes differs from hypoglycemia.
10. Identify alternative sweeteners used as sugar
substitutes.
What Are Carbohydrates and
Why Do You Need Them?
Found primarily in plant-based foods
 Grains, vegetables, fruits, nuts, legumes
 Carbohydrate-based foods are staples in numerous
cultures around the world
Most desirable form of energy for body
 In form of glucose (-ose = carbohydrate)
 Brain and red blood cells especially rely on glucose as
a fuel source
Where Do Carbohydrates Come From?
 Plants convert the sun’s energy into glucose by
photosynthesis
 Glucose (C6H1206) is most abundant carbohydrate
found in nature
 Used as energy by plants or combined with minerals from soil to
make other compounds, such as protein and vitamins
 Glucose units linked together and stored in form of
starch
Animation: Hormonal Control of
Blood Glucose
Photosynthesis: How Glucose Is Made
Figure 4.1
What Are Simple and Complex
Carbohydrates?
Simple carbohydrates: monosaccharides and
disaccharides
 Three monosaccharides: glucose, fructose,
galactose
 Disaccharides: two monosaccharides, chemically
joined together
 Maltose = glucose + glucose
 Sucrose (table sugar) = glucose + fructose
 Lactose (milk sugar) = glucose + galactose
What Are Simple and Complex
Carbohydrates?
Complex carbohydrates: polysaccharides
 Long chains and branches of sugars linked
together
 Starch, fiber, and glycogen
 Starch is the storage form in plants.
 Amylose: straight chains of glucose units
 Amylopectin: branched chains of glucose units
Creating Monosaccharides,
Disaccharides, and Polysaccharides
Figure 4.2
Fiber is Non-digestible but is Very
Important to the Body
Fiber is part of plant that we eat but cannot digest
 Examples: cellulose, hemicellulose, lignins, gums, pectin
 Humans lack digestive enzyme needed to break down
fiber
 Dietary fiber: naturally found in foods
 Functional fiber: added to food for beneficial effect
 Example: Psyllium added to cereals
 Total fiber = dietary fiber + functional fiber
The Two Types of Fiber
Fiber is classified by its affinity for water
1. Soluble fiber: dissolves in water and is fermented by
intestinal bacteria

Many are viscous, have thickening properties

Move more slowly through GI tract

Examples: Pectin in fruits and vegetables, beta-glucan in oats
and barley, gums in legumes, psyllium
2. Insoluble fiber: cellulose, hemicellulose, lignins

Move more rapidly through GI tract, laxative effect

Examples: bran of whole grains, seeds, fruits, vegetables
Most Plant Foods Contain Both
Soluble and Insoluble Fiber
Figure 4.3
What Are Simple and Complex
Carbohydrates?
Glycogen is the storage form of glucose in
animals
 Branched glucose similar to amylopectin
 Stored in liver and muscle cells
 Only limited amounts
 Important source of glucose for blood
Nutrition in the Real World: Grains,
Glorious Whole Grains
Grains: important staple and source of nutrition
 Three edible parts: bran, endosperm, germ
 Refined grains: milling removes bran and germ
 Some B vitamins, iron, phytochemicals, and dietary fiber lost
as a result
 Examples: wheat or white bread, white rice
 Enriched grains: folic acid, thiamin, niacin, riboflavin
and iron added to restore some of the lost nutrition
 Whole grain foods contain all three parts of kernel
 Examples: brown rice, oatmeal, whole-wheat bread
From Wheat Kernel to Flour
Misc 4.1
What Happens to the Carbohydrates
One Eats?
Digesting a meal of pasta (starch), milk (lactose)
and cherries (sucrose and fiber):
 You digest carbohydrates in your mouth and
intestines
 Saliva contains amylase enzyme (-ase = enzyme)
 Starts breaking down amylose and amylopectin
in pasta into smaller starch units and maltose
Animation: Carbohydrate
Absorption
Animation: Carbohydrate
Digestion
From Carbohydrates to Glucose in
the Body
Figure 4.4
Some People Cannot Digest Milk Sugar
 Lactose: principal carbohydrate found in
dairy products
 People with a deficiency of the enzyme lactase
cannot digest lactose properly
 Lactose mal-digestion is natural part of aging
 As soon as a baby stops nursing, body makes
less lactase
 Lactose intolerance: when lactose maldigestion results in nausea, cramps, bloating,
diarrhea, and flatulence
Some People Cannot Digest Milk Sugar
Helpful tips for tolerating lactose:
1. Gradually add dairy products to the diet
2. Eat smaller amounts throughout day rather than large
amount at one time
3. Eat dairy foods with a meal or snack
4. Try reduced-lactose milk and diary products
5. Lactase pills can be consumed with lactose-laden
meals or snacks
How Much Lactose is in Food?
Table 4.1
How Does the Body Use
Carbohydrates?
 Glucose supplies energy for body, required for brain,
nervous system, red blood cells
 Fat can also provide fuel for muscle, other tissues
 Hormones regulate amount of glucose in blood
 Insulin is released by pancreas in response to high
blood glucose levels after a carbohydrate-rich meal
 Directs conversion of glucose in excess of immediate
energy needs into glycogen (glycogenesis) in liver and
muscle cells (limited capacity)
 The remainder of excess glucose is converted to fat
Generating Energy from Glucose
Figure 4.5
Carbohydrates Fuel Your Body Between
Meals
 When blood glucose begins to drop, pancreas
releases the hormone glucagon to raise blood
glucose levels
 Directs release of glucose from stored glycogen in liver =
glycogenolysis
 Signals liver to start gluconeogenesis = making glucose from
non-carbohydrate sources, mostly protein
 Epinephrine (adrenalin) also stimulates
glycogenolysis and increases blood glucose
levels
 “Fight or flight” hormone: stress, bleeding, low blood glucose
levels trigger its release
Carbohydrates (cont.)
 Liver glycogen stores depleted after about 18 hours
 Without glucose, fat can’t be broken down completely and
ketone bodies are produced, which are highly acidic.
 Ketosis: elevated blood Ketone levels after fasting for about
two days
 Protein from muscle and organs can be broken down to
make glucose
 Brain switches to using the ketone bodies for energy to spare
protein-rich tissues.
 If fasting continues, protein reserves are depleted and
death can become inevitable.
Hormones Help Maintain Healthy
Blood Glucose Levels in the Body
Figure 4.6
How Much Carbohydrate Do You Need
and What Are the Best Food Sources?
 Minimum amount of carbohydrates needed
daily
 DRI: 130 grams per day for brain function
 Consume diet with low-to-moderate amounts of
simple carbohydrates and higher amounts of fiber
and other complex carbohydrates
 Low fat dairy, whole grains, whole fruits, vegetables,
legumes, nuts, and seeds provide natural simple
carbohydrates and/or complex carbohydrates
What are Your Daily Fiber Needs?
Table 4.2
Food Sources of Carbohydrates
Figure 4.7
How Much Carbohydrate Do You Need
and What Are Its Food Sources?
Filling Up on Fiber
 DRI: 14 grams of fiber per 1,000 calories to
promote heart health
 Most Americans fall short: about 15 grams per
day
 Gradually increasing fiber in your diet will minimize
side effects, such as flatulence
 As you add fiber to your diet, you should also
drink more fluids
Food Sources of Fiber
Soluble Fiber
Figure 4.8
What’s the Difference Between
Natural and Added Sugars?
Naturally occurring sugars found in fruits and dairy
 Usually more nutrient dense; provide more nutrition
per bite
Added sugars are added by manufacturers and are
often “empty calories” (provide little nutrition).
 Examples: soda, candy
Taste buds cannot distinguish between
naturally occurring and added sugars
How Much Sugar? Cutting Excess
From Your Diet
Why is sugar such a problem and
how can one decrease his/her
intake?
Slices of an Orange versus Orange Slices
Figure 4.9
Processed Foods and Sweets
Often Contain Added Sugars
 Yearly consumption of added sugars increased more than
20 percent between 1980 and 2000
 Research doesn’t support claims of sugar causing
hyperactivity and diabetes
 Obesity and dental caries are major health issues
 Too much sugar can increase the blood triglycerides, lower
the “good” HDL cholesterol, may increase the risk of heart
disease
 Moderation, balance, and staying within daily calorie needs
essential when it comes to added sugars
Processed Foods and Sweets
Often Contain Added Sugars
Finding the added sugars in your foods:
 Sugars on food labels appear under numerous
different names
 Honey and fructose are not nutritionally superior to
sucrose
 Naturally occurring sugars are not distinguished from
added sugars on the Nutrition Facts panel
Nutrition in the Real World: Avoiding a
Trip to the Dentist
Carbohydrates play a role in dental caries
 Fermentable sugars and starch feed bacteria coating
teeth, producing acid which erodes tooth enamel
 Tips to minimize tooth decay:
1. Eat three balanced meals daily

Keep snacking to a minimum, choosing whole fruits and
raw vegetables
2. Include foods that fight dental caries: cheese,
sugarless gum
3. Regular dental care and good dental
hygiene
Finding Added Sugars on the Label:
The Many Aliases of Added Sugar
Figure 4.10
Where Are All These Added
Sugars Coming From?
Figure 4.11
The Many Sizes of Soft Drinks
Figure 4.12
What Are Sugar Substitutes and
What Forms Can They Take?
Sugar substitutes are as sweet or sweeter than
sugar, but contain fewer calories
 Must be approved by FDA and deemed safe before
allowed in food products in the United States
Polyols (sugar alcohols): sorbitol, mannitol, xylitol
 Absorbed more slowly than sugar, don’t cause
spike in blood glucose but not calorie free
 Not completely absorbed, can cause diarrhea
What Are Sugar Substitutes and
What Forms Can They Take?
Calorie-Free Sweeteners:
1.
Saccharin (Sweet’N Low®): 200 to 700 percent sweeter than
sucrose
2.
Aspartame (Nutrasweet®, Equal®): 200 percent sweeter
1.
Derived from aspartic acid and phenylalanine.
2.
People with phenylketonuria (PKU) need to monitor all dietary
sources of phenylalanine, including aspartame.
3.
Acesulfame-K (Sunette®): 200 percent sweeter
4.
Sucralose (Splenda®): 600 percent sweeter
5.
Rebaudioside A (Truvia®, PureVia®): 200 percent sweeter
6.
Neotame: 7,000 to 13,000 percent sweeter
Stevia Plant
Growing Interest in Sugar-Free
Foods and Beverages
Figure 4.13
Oh, So Sweet…
Table 4.4
Why Is Fiber So Important?
Fiber is resistant to digestion but has many
powerful health effects.
Fiber helps lower risk of developing:
1.
2.
3.
4.
Constipation
Diverticulosis, diverticulitis
Obesity: high-fiber foods add to satiation
Heart disease: soluble fibers lower elevated blood
cholesterol levels
5. Colorectal cancer
6. Diabetes mellitus: slow digestion and absorption of
glucose
Type Casting Fiber
Table 4.5
Diverticula
Figure 4.14
Jump Start Your Diet: Put More
Fiber on Your Plate
What is Fiber?
Jump Start Your Diet: Put More
Fiber on Your Plate
1. What are five essential foods that are high in fiber
content?
2. What does fiber do in the body to improve your overall
health?
3. How much fiber do you need to consume each each day?
4. What is the best way to incorporate more fiber into you
diet?
What Is Diabetes Mellitus and Why Is It
an Epidemic?
 Diabetes mellitus: individual has high blood
glucose levels due to insufficient insulin or insulin
resistance
 Glucose can’t enter cells, which burn fat for fuel
 Without glucose, acidic ketone bodies build up,
causing life-threatening diabetic ketoacidosis:
untreated can result in coma, death
 Type 1 diabetes: 5 to 10 percent of cases
 Autoimmune disease: insulin-producing cells in pancreas
destroyed—insulin injections required
 Develops in childhood, early adult years
How Diabetes Affects The Body
Pancreas
produces
sufficient
insulin
Glucose absorbed
after a meal
Glucose
levels in
bloodstream
rise
Pancreas
does not
produce
sufficient
insulin
Glucose
Insulin • Body cells take levels
Normal fasting
up glucose
glucose:
• Suppression of
liver glucose in blood 70-100 mg/dL
output
fall
• Suppression of
fat release from
body stores
High
• Body cells
levels of can’t take
up glucose
glucose • Body uses
in blood stored fat
• Damage to
blood vessels
• Risk of kidney
damage,
blindness,
amputation,
heart attack,
stroke
What Is Diabetes Mellitus and Why Is It
an Epidemic?
 Type 2 diabetes: 90 to 95 percent of cases
 Cells are resistant to insulin, eventually insulin-producing
cells are exhausted, pancreas decreases and medication
and/or insulin is required
 People 45 and older or at risk for diabetes should
be tested.
 Prediabetes: impaired glucose tolerance
 Blood glucose higher than normal but not yet high
enough to be classified as diabetes
 Damage to heart and circulatory system can occur.
Interpreting Blood Glucose Levels
Table 4.6
What Is Diabetes Mellitus and Why Is It
Such A Public Health Issue?
Diabetes can result in long-term damage
 High blood glucose levels damage vital organs
1. Nerve damage, numbness, poor circulation
 Infections, leg and foot amputations
2. Eye damage, blindness
3. Tooth and gum problems
4. Kidney damage
5. Increased risk of heart disease
Diabetes Mellitus (cont.)
 Blood glucose control is the key
 Nutrition and lifestyle goals:
 Physical exercise
 Well-balanced diet containing:
1. High-fiber carbohydrates from whole grains,
fruits, vegetables
2. Low-fat milk
3. Adequate lean protein sources
4. Unsaturated fats
5. Proportionate meal size
Diabetes Mellitus (cont.)
 Glycemic index (GI) and glycemic load (GL)
classify effects of carbohydrate-containing foods on
blood glucose
 GI: ranks foods’ effects on blood glucose compared with
equal amount of pure glucose
 GL: adjusts GI to take into account the amount of
carbohydrate consumed
 Eating carbohydrate-heavy foods with protein, fat
lowers GI
 Sugar is not prohibited; starch causes same rise in
blood glucose levels
 Total calories important for weight management
The Glycemic Index of Commonly Eaten
Foods
Figure 4.15
Glycemic Load vs. Glycemic Index
• Number that estimates how much the food will raise
a person's blood sugar level after eating it.
• One unit of glycemic load approximates the effect of
consuming one gram of glucose.
• Glycemic load accounts for how much carbohydrate
is in the food and how much each gram of
carbohydrate in the food raises blood sugar levels.
• Glycemic load is based on the glycemic index (GI),
and is defined as the grams of available carbohydrate
in the food times the food's GI.
Effects of High- & Low-Glycemic
Intake on Blood Glucose Levels
Hungar
Returns
© Cengage
Publishing
LPFW 66
Delay of
Hungar
What Is Diabetes Mellitus and Why Is It
an Epidemic?
Cases of diabetes are on the rise
 Sixth leading cause of death in the United States.
 Over 200,000 Americans die from diabetic
complications annually
 Rapidly rising in children
 Obesity, overweight, and physical inactivity
increase risk
Preventing type 2 diabetes:
 Losing excess weight, physical exercise, hearthealthy, plant-based diet
Red Flags for Children and Adolescents
Table 4.7
What Is Hypoglycemia?
Hypoglycemia: blood glucose level below
70 mg/dl
 Symptoms: hunger, shakiness, dizziness, perspiration,
light-headedness
 May occur in people with diabetes when they don’t eat
regularly to balance effects of insulin or blood glucoselowering medication
 Can cause fainting, coma
 Reactive hypoglycemia: uncommon condition in people
without diabetes within four hours after eating
 May be oversensitive to epinephrine
Change in Blood Glucose After
Eating a High-Carbohydrate Meal
Figure 4.16
The End
Slide Show developed by:
Richard C. Krejci, Ph.D.
Professor of Public Health
Columbia College