CARBOHYDRATES
Learning Objectives:
• Understand the different classes of
carbohydrates
• Understand the digestion and
absorption of carbohydrates
• Learn about the function of
carbohydrates in the diet, and how they
relate to health issues
WHAT ARE THE
CARBOHYDRATES?
•
Organic compounds that contain
CARBON, HYDROGEN, and OXYGEN
in the ratio of 1 carbon atom and 1 oxygen
atom for every 2 hydrogen atoms
•
Two Main Classes:
SIMPLE (sugars)
COMPLEX (starches and fiber)
•
•
SIMPLE SUGARS
•
MONOSACCHARIDES
•
Glucose (or Dextrose)
Galactose
Fructose
•
•
SIMPLE SUGARS
•
DISACCHARIDES
•
Sucrose
(glucose+fructose)
Lactose
(glucose+galactose)
Maltose
(glucose+glucose)
•
•
COMPLEX
CARBOHYDRATES
POLYSACCHARIDES
• Starch - long chains of glucose
molecules in straight (AMYLOSE) or
branching (AMYLOPECTIN)
arrangement
• Figure 4-8, page 106
COMPLEX CARBOHYDRATES
POLYSACCHARIDES
• Glycogen – animal form of starch
(highly branched and composed of
multiple glucose molecules)
COMPLEX
CARBOHYDRATES
FIBER – resembles starch, but cannot
be digested
TYPES:
• Cellulose
• Hemicellulose
• Pectin
• Gums and Mucilages
• Lignans (is fiber, but not a polysaccharide)
•
CLASSIFICATION of FIBER
•
SOLUBLE – dissolve in water
INSOLUBLE – cannot dissolve in
water
Table 4-3, page 123
•
Daily recommendations?
•
•
B=
1 cup orange juice
2 scrambled eggs
1 slice white toast
L=
1 cup chicken noodle soup
1 cup iceburg lettuce
1 Tbsp blue cheese dressing
D=
1 pork chop
1 cup white rice
½ cup canned corn
1 baked potato (no skin)
1 danish
S=
1 oz. cheddar
4 saltine crackers
DIGESTION
•
•
•
MOUTH - amylase
STOMACH
SMALL INTESTINE – pancreatic amylase,
disaccharidases, maltase, sucrase, lactase
•
all three travel to the
liver through the portal
vein; galactose and
fructose are converted
to glucose
CARBOHYDRATES in the
BODY
USE OF GLUCOSE
• Energy – glucose is the primary fuel for most cells
in the body. The brain MUST have glucose!
• Sparing body protein – if glucose is scarce, the
body will breakdown its own protein.
• Preventing ketosis – with no carbohydrate, fat
breakdown produces ketone bodies. Can lead to
ketosis.
• Storage as glycogen – liver stores are used to
maintain blood sugar, while muscle stores are used
to fuel activity.
REGULATING BLOOD
GLUCOSE LEVELS
•
•
•
Insulin – lowers blood glucose
Glucagon – raises blood glucose
Epinephrine – “fight-or-flight”
hormone
GLYCEMIC INDEX
•
Classifies food or meals based upon their potential
to raise blood glucose levels
Expressed as a percentage of the response to a
standard carbohydrate, usually white bread or pure
glucose
Useful? – decreased risk of NIDDM, heart
disease, and colon cancer
Useless? – complex, research may not support it
•
page 116
•
•
•
HIGH BLOOD SUGAR Diabetes
•
•
Type I – Insulin Dependent Diabetes
Mellitus (IDDM) or Juvenile Onset
Type II – Non Insulin Dependent
Diabetes Mellitus (NIDDM) or Adult
Onset
HIGH BLOOD SUGAR Diabetes
RISK FACTORS
• Type I – genetics
• Type II – genetics, >45 years old,
overweight, sedentary, low HDL or
high triglycerides, certain racial or
ethnic groups, gestational diabetes
Page 639
HIGH BLOOD SUGAR Diabetes
CONSEQUENCES
• Peripheral vascular disease
• Deterioration of the eye
• Kidney disease
• Progressive nerve damage
• Heart disease
CARBOHYDRATES in the
DIET
•
•
•
•
Recommendations
Current consumption
Increasing complex carbohydrate
Moderating sugar intake
CARBOHYDRATES and
HEALTH - Sugar
•
•
Sugar and nutrient intake: empty
calories
Sugar and dental caries: ex. babybottle tooth decay
Sugar Substitutes
Saccharine (Sweet & Low)
 Sucralose (Splenda)
 Aspartame (Nutrasweet)

0 kcals/g
0 kcals/g
4 kcals/g
Sugar Replacers
Isomalt
Lactitol
Maltitol
Mannitol
Sorbitol
2.0 kcal/g
2.0 kcal/g
2.1 kcal/g
1.6 kcal/g
2.6 kcal/g
“Sugar-Free” does not necessarily mean free of
calories!
High Fructose Corn Syrup?
 Produced by milling corn to produce corn
starch, then processing that corn starch to
yield corn syrup (almost entirely glucose),
and then adding enzymes which change the
glucose into fructose


Are all sugars the same? Page 118
CARBOHYDRATES and
HEALTH – Complex
Carbohydrates
A diet rich in complex carbohydrates lowers
the risk of:
• Obesity
• Type II Diabetes
• Cancer
• Cardiovascular Disease
• Gastrointestinal Disorders
Compared to Whole Wheat, White
Bread is Missing:
96% of Vitamin E
 78% of Fiber
 72% of Magnesium
 62% of Zinc
 78% of Vitamin B6
 Plus Phytochemicals

How Does Soluble Fiber Reduce Cholesterol?
Two Ways…
Enterohepatic Circulation of Bile (page 149
“Bile’s Routes”)
 Bacterial by-products of fiber fermentation
in the large intestine inhibit cholesterol
synthesis in the liver

Fiber Supplements
Benefits?
 Risks?
