The Carbohydrates
Sugars
Starches
Fiber
Objectives
• After reading Chapter 3 and class
discussion, you will be able to:
– Describe the functions of CHO
– Identify the classification of CHO
– Describe CHO digestion & absorption
– Identify food sources of CHO
– Calculate calories from CHO
Objectives
• Differentiate between soluble and
insoluble fiber
• Identify foods that are a significant
source of fiber
• Discuss health related effects of
CHO in
– Diabetes
– Obesity
-GI
-Heart Disease
-Cancer
Photosynthesis
• Plants make their
own carbohydrates
from
– carbon dioxide in air
– water from the soil
• Photosynthesis
converts energy from
sunlight into energy
stored in
carbohydrates
4
Categories of Carbohydrate
• Simple
carbohydrates
– Natural sugars
– Added (Refined)
sugars
• Complex
carbohydrates
(polysaccharides)
– Starch
– Fiber
5
Carbohydrates
• Simple carbohydrates
–Monosacchares
–Disaccharides
• Complex carbohydrates
–Glycogen
–Starches
–Fibers
Glucose
Fructose & Galactose
p. 103
Monosaccharides and
Disaccharides
9
Disaccharides
• Maltose
– Glucose + glucose
– Starch breakdown; fermentation
– Barley
• Sucrose
– Glucose + fructose
– Table sugar from sugarcane, sugar beet
• Lactose
– Gucose + galactose
– Milk
Complex Carbohydrates
• Polysaccharides
–Glycogen
•Storage form of glucose
•Stored in liver and muscles
–Starches
•Long chains of glucose linked together
•Straight or branched chains
–Fibers
•Soluble or viscous
•Insoluble or nonviscous
Complex Carbohydrates
Chemical Structure
p. 109
Fig 3-7
Complex Carbohydrate:
Starch
• Amylose - straight glucose chain
• Amylopectin – branched glucose
chain
• Found only in plant foods: grains,
legumes, vegetables, some fruits.
• Gelatinization – When starches are
heated, they absorb water and
swell in size.
13
Complex Carbohydrates
• Fibers
–Cellulose
–Hemicelluloses
–Pectins
–Legnin
–Gums and muscilages
–Resistant starches
p. 108-109
Complex
Carbohydrates
• Fibers
–Soluble fibers-dissolve in water
•Viscous-form gels
•Fermentable-digested in colon
by bacteria
Complex
Carbohydrates
• Fibers
–Insoluble fibers
•Nonviscous
•Fermented less readily
• Phytic acid-binds minerals
Carbohydrate Categories
• Sugars
• Starches
• Fibers
OR
• Simple
• Complex
Carbohydrate Categories
• Monosaccharide
– Glucose
-Fructose
-Galactose
• Disaccharide
– Maltose
-Sucrose
-Lactose
• Polysaccharide
– Glycogen
-Starches
-Fibers
Functions of Carbohydrate
• Primary source of body’s energy
– Central nervous system and red blood
cells rely almost exclusively on glucose.
– Glucose stored in liver & muscles as
glycogen.
• Protein sparing
– Prevents breakdown of protein for
energy (gluconeogenesis)
• Prevents ketone bodies & ketosis
– Breakdown of fat for energy
20
Digestion
• Mouth
–Salivary amylase
–Mechanical mixing; chewing
• Stomach
– Continued mixing of bolus
– Fibers and satiety
• Small intestine
– Maltase, Sucrase, Lactase
Digestion
• Pancreas
– Pancreatic amylase
• Large intestine – Colon
– Fermentation of viscous fibers
• Water, gas, short-chain fatty-acid
production
Absorption
Carbohydrates and Health
• Lactose
Intolerance
• Diabetes
• Dental caries
• Constipation
• Hyperactivity
• Obesity
• Heart Disease
Lactose Intolerance
• Symptoms
– Abdominal discomfort
– Bloating; Intestinal gas formation
– Diarrhea
• Causes
–Primary: Lactase deficiency
–Secondary: Mucosal damage
p. 110
Lactose Intolerance
• Prevalence (p. 111)
• Ethnic <10% to >80%
–
–
–
–
–
–
–
–
<10% Northern Europeans (Scandinavians)
20% Caucasians
50% Hispanics
60% Inuits
70% Mediterranean peoples
75% African Americans
80% Native Americans
>80% Southeast Asians
Lactose Content of Food
• Whole wheat bread 1 slice
• Cheese
1 oz
•
•
•
•
•
•
•
– Cheddar/American
– Parmesan/Cream
Doughnut, cake type
Chocolate 1 oz
Sherbet
1c
Cottage cheese
Ice Cream 1 c
Milk
1c
Yogurt
1c
0.5gm
0.5-0.8
1.2
2.3
4.0
7.5
9.0
12.0
15.0
Lactose Intolerance
• Dietary changes
–May not require the elimination
of milk/milk products
–Acidophilus milk
–Kefir, yogurt
–Adequate calcium intake
–Conservative vs liberal approach
Blood Glucose
• Regulating hormones
–Insulin
•Controls transport of glucose
–Glucagon
•Release glycogen from liver stores
–Epinephrine
•Signals liver to release glucose
p. 104
• How the
body
regulates
blood
glucose
p. 114
Blood Glucose
• Hypoglycemia
– Rare in healthy people
• Diabetes
–Type 1 diabetes
•Failure of insulin production
–Type 2 diabetes
•Obesity
Blood Glucose
• Glycemic response
– How quickly and how
high blood sugar rises
after eating
• Glycemic index
– Method of classifying
foods according to their
potential for raising
blood glucose
p. 118
Blood Glucose
CAUTION
• Glycemic Load
– Refers to both the Glycemic
Index and the total amount of
carbohydrate contained in the food
• Factors Influencing Glycemic Index
– Effect of mixed meal
– Fat, fiber, protein content of food
– Amount and type of CHO eating
Added Sugars
• Sugars added to a
food for sweetening
or other purposes
– Do not include
natural sugars
• Other purposes:
– Prevent spoilage
– Browning
– Food for yeast
– Hold moisture
p. 100-102
Examples of Added Sugars
• White sugar (sucrose)
• High-fructose corn syrup or corn
syrup
• Invert sugar
• Brown sugar
• Molasses
• Honey
• Powdered sugar
• Raw sugar
• Demerara sugar
38
Sugars
• Nutrient
density
• Overused in
USA
p. 101
Sugars
• Health effects of
sugars
–Dental caries
•Dental plaque
p. 102
Controversies
Of Sugar
• Sugar causes
obesity
• Sugar causes
heart disease
p. 104
Controversies
Of Sugar
• Sugar causes misbehavior in
children and criminal behavior in
adults
• Sugar causes cravings and
addictions
–Serotonin- mood elevator
p. 105
Recommended
Intakes of Sugars
• DRI
–No more than 25% of total daily
energy intake
•Average U.S. Intake=105#/yr
» 30 teaspoons/day
Starch and Fiber
• Health effects
–Heart disease
–Diabetes
–GI health
–Cancer
–Weight
management
Viscous Fibers
• SOLUBLE and more fermentable
• Gums and mucilages
• Pectins
• Psyllium
• Some hemicelluloses
Viscous Fibers
• Sources
–Whole-grains, fruits, legumes,
seeds and husks, vegetables
Viscous Fibers
• Lower blood cholesterol
• Slow glucose absorption
• Slow transit of food through upper
GI tract
• Holds moisture in stools, softening
them
Viscous Fibers
• Yield small fat molecules that the
colon can use for energy
• Lower risk of heart disease
• Lower risk of diabetes
Viscous Fibers
Nonviscous Fibers
• INSOLUBLE and less fermentable
• Cellulose
• Lignins
• Psyllium
• Resistant starch
• Many hemicelluloses
Nonviscous Fibers
• Sources
–Brown rice, fruits, legumes,
seeds, vegetables, wheat bran,
whole grains
–Extracted and used as food
additives
Nonviscous Fibers
• Increase fecal weight
• Speed fecal passage through colon
• Provide bulk and feelings of
fullness
Nonviscous Fibers
• Alleviate constipation
• Lower risks of diverticulosis,
hemorrhoids, appendicitis
• May help with weight management
Nonviscous Fibers
Starch and Fiber
• RDA for carbohydrate
–130 g/day
–45% - 65% total daily energy
intake
• Daily Value: 300 g/day; 60% of
2000 kcal diet
• Fiber
Starch and Fiber
• RDA for carbohydrate
–130 g/day
–45% - 65% total daily energy
intake
• Daily Value: 300 g/day; 60% of
2000 kcal diet
• Fiber
– Daily Value: 25 gm/day
– AI: 14 gm/1000 kcal/day
Fiber
• Grains
– Whole
Wheat
or
– 100%
Wheat
vs
– Wheat
Bread
More on Fiber
• Vegetables
– ½ c. dry beans, carrots=5-7 gms
– ½ c. corn=2 gm; 1c. tomatoes=2 gm
– ½ c. broccoli=3-6 gm
• Fruits
– 1 pear=4-6 gm; canned=4 gm/1c
– 1 apple=3-5
– 1 banana, orange=3
Fiber and Food Processing
• How much fiber is there in each
food?
1 apple
1 c. applesauce
1 c. apple juice
Robertson’s Rule of 2’s
Food Item
Amount
Dietary Fiber
100% Bran cereal 1/2 cup or
or Miller’s Bran
2 Tablespoons
10-14 grams
Whole Wheat
Bread
2 slices
4 grams
Fresh Fruit
2 pieces
4 grams
Vegetables
2 servings
4 grams
Total
22-26 grams
Alternatives to Sugar
• Artificial sweeteners & sugar replacers
(nutritive sweeteners)
• Stevia-natural, herbal alternative
• Guidelines for Use:
–More sweet than sugar; use less
–FDA approved (p.134; H4-1;H4-3 )
–Caution when used in cooking
Alternatives to Sugar
• Caution: Patients with PKU
• Acceptable Daily Intake (ADI)
p. 135-138
Objectives
• After reading Chapter 3 and class
discussion, you will be able to:
– Describe the functions of CHO
– Identify the classification of CHO
– Describe CHO digestion & absorption
– Identify food sources of CHO
– Calculate calories from CHO
Objectives
• Differentiate between soluble and
insoluble fiber
• Identify foods that are a significant
source of fiber
• Discuss health related effects of
CHO in
– Diabetes
– Obesity
-GI
-Heart Disease
-Cancer