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Carbohydrates
Intended Learning Outcomes
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By the end of this lecture, students will have a
general overview on the carbohydrates.
Can you live without
sugar?
 Soda/Punch
 Cookies
 Candy
 Chocolate
 Desserts
 Sugary Cereals
 Ice cream
CARBOHYDRATES
1. 60% of our
food should
come from
carbohydrates
.
Carbs
Protein
Fats
2. Carbohydrates are grains,
fruits, vegetables, legumes
and sugar.
Carbohydrates
 glucose provides energy for the
brain and ½ of energy for
muscles and tissues
 glycogen is stored glucose
 glucose is immediate energy
 glycogen is reserve energy
CARBOHYDRATES
3. Carbohydrates give
the body energy.
They are the best
source of fuel for the
body.
Carbohydrates also
help to digest
protein and fat.
Carbohydrates
 2. Carbohydrates also play a vital
part of the metabolism and
oxidation of protein
 Carbs help feed the brain and
nervous system and helps keep the
body lean.
CARBOHYDRATES
4. If we eat more
carbohydrates than
are needed for
energy, the extra is
stored in the liver or
in the tissues as fat.
Carbohydrates
 5. all plant food
 Milk (LACTOSE)
 carbohydrates are not equal
–simple carbohydrates
–complex carbohydrates
Simple Carbohydrates
6. Simple carbohydrates are quick
energy sources. They come from
sugar. They do not usually supply
any other nutrients or fiber.
Simple Carbohydrates
 sugars
–monosaccharides – single sugars
–disaccharides – 2 monosaccharides
Simple Carbs
 monosaccharides
–all are 6 carbon hexes
6 carbons
12 hydrogens
6 oxygens
arrangement differs
–accounts for
varying sweetness
–glucose, fructose,
galactose
Glucose
 mild sweet flavor
 10. known as blood
sugar
 essential energy
source
 found in every
disaccharide and
polysaccharide
Fructose
 sweetest sugar
 found in fruits and
honey
 added to soft drinks,
cereals, deserts
Galactose
 hardly tastes
sweet
 rarely found
naturally as a
single sugar
Disaccharides
 pairs of the monosaccharides
–glucose is always present
–2nd of the pair could be fructose,
galactose or another glucose
–taken apart by hydrolysis
–put together by condensation
–hydrolysis and condensation occur
with all energy nutrients
–maltose, sucrose, lactose
Maltose
 2 glucose units
 produced when starch breaks down
 not abundant
Sucrose
 fructose and glucose
 tastes sweet
–fruit, vegetables,
grains
 table sugar is refined
sugarcane and
sugar beets
 brown, white
,powdered
Lactose
 glucose and galactose
 main carbohydrate in
milk
– known as milk sugar
Simple Sugars
7. Glucose or blood sugar is the
basic source of energy for all
living things.
8. Sucrose or table sugar is
made from sugar beets or
sugar cane.
9. Fructose is sugar found in
fruit, honey and vegetables.
11. Maltose is grain starch
broken down into sugar.
12. Lactose is milk sugar.
Complex Carbohydrates
 starches and fibers
 polysaccharides
–chains of monosaccharides
Complex
Carbohydrates
13. Complex
carbohydrates supply
longer lasting energy,
as well as other
nutrients and fiber that
the body needs. They
are a better choice.
Condensation
 making a
disaccharide
–chemical reaction
linking 2
monosaccharides
Hydrolysis
 breaking a disaccharide
–water molecule splits
–occurs during digestion
Complex Carbohydrates
 polysaccharides
–1.glycogen and 2.starch
built entirely of glucose
–3.fiber
variety of monosaccharides and
other carbohydrate derivatives
Glycogen
 limited in meat and not found in plants
–not an important dietary source of
carbohydrate
 BUT
–all glucose is stored as glycogen
–long chains allow for
hydrolysis and release
of energy
Starches
 stored in plant cells
 body hydrolyzes plant starch to
glucose
STARCHES
 14. Starch in the body breaks down
simple sugars. The body has to break
down all sugar and starch into glucose
to use it.
Starchy Foods
 15. All starchy foods are
plant foods, seeds are the
richest source; 70% of their
weight is starch
Fiber
 structural parts of plants
–found in all plant derived food
 bonds of fibers cannot be
broken down during the
digestive process
–minimal or no energy available
Fiber types
 cellulose
 pectins
 lignins
 resistant starches
– classified as fibers
– escape digestion and
absorption
Fiber Characteristics
 soluble fibers, viscous, fermentable
–easily digested by bacteria in colon
–associated with protection against
heart disease and diabetes
lower cholesterol and glucose
levels
–found in legumes and
fruits
Fiber
1. The average American does not get
enough FIBER in their diets.
2. The National Cancer Institute
recommends that the average
person gets 20-35 GRAMS of fiber
every day.
3. Two other common names for fiber
are: ROUGHAGE or CELLULOSE.
4. Fiber is important because it attracts
WATER to the INTESTINES and
helps move food through our
systems faster. You have to have
water along with fiber or it is not as
effective.
5. Benefits of fiber include a lowered
risk of DIVERTICULITUS,
HEMORRHOIDS and COLON or
RECAL CANCER.
6. List the two types of fiber and the main
functions they perform:
7. Fiber only comes from PLANT food
sources. You CANNOT get fiber from
animal food sources.
8. Foods that are high in fiber include:
• Fruits and Veggies (Especially the
Skins!)
• Whole Grains
• Legumes/Beans - Bran
9. Ways to increase fiber in the diet include:
• Add Whole Grains (At least 3 oz. per
day)
• Use Whole Wheat FlourEat the Skins
10. Label the Wheat Kernel below:
A.__ENDOSPERM___
Provides:
Starch
Protein
B. __GERM___
Provides:
Unsaturated Fatty Acids
“B” Vitamins
Vitamin E
Iron
Zinc
Other Trace Minerals
C. __Bran___
Provides:
Fiber
Vitamins
Minerals
11.When a product claims that it is “Whole
Wheat” or “Whole Grain”, it must use
the ENTIRE wheat kernel, or ALL
THREE parts.
12.Other products, like white bread and
rice, usually only use the
ENDOSPERM, which is the LEAST
beneficial part of the wheat kernel.
13.ENRICHED: some of the nutrients that
were lost in processing are added back
into the product.
14.FORTIFIED: 10% more of the Daily
Fiber
 insoluble and not easily fermented
– promote bowel movements
– alleviate constipation
– found in grains and vegetables
DRI and Fiber
 distinguish fibers by source
– dietary fibers: naturally in intact plants
– functional fibers: extracted from plants or
manufactured
– total fiber: sum of the 2
Carbohydrate Digestion
 break down into glucose
– body is able to absorb and use
 large starch molecules
– extensive breakdown
 disaccharides
– broken once
 monosaccharides
– don’t need to be broken down
Carbohydrate Digestion
 begins in mouth
– chewing releases saliva
– enzyme amylase hydrolyzes starch to
polysaccharides and maltose
 stomach
– no enzymes available to break down
starch
– acid does some breakdown
– fibers in starch provide feeling of fullness
small intestine
majority of carbohydrate digestion
takes place here
pancreatic amylase reduces carbs to
glucose chains or disaccharides
specific enzymes finish the job
maltase
maltose into 2 glucose
sucrase
sucrose into glucose and fructose
lactase
lactose into glucose and
galactose
large intestine
1-4 hours for sugars and starches to
be digested only fibers remain
attract water, which softens stool
bacteria ferment some fibers
water, gas, short-chain
fatty acids
(used for energy)
Carbohydrate Absorption
 glucose can be absorbed in the mouth
 majority absorbed in small intestine
– active transport
 glucose and galactic
– facilitated diffusion
 fructose
 smaller rise in blood glucose
Lactose Intolerance
 more lactose is consumed than can be
digested
– lactose molecules attract water
 cause floating, abdominal discomfort,
diarrhea
– intestinal bacteria feed on undigested
lactose
 produce acid and gas
Lactose Intolerance
 age, damage, medication, diarrhea,
malnutrition
 management requires dietary change
– 6 grams (1/2 cup) usually tolerable
– take in gradually
– hard cheeses & cottage cheese
– enzyme drops or tablets
 lactose free diet is extremely difficult to
accomplish
Carbohydrate Metabolism
1/3 of body’s glycogen is stored in liver
– released as glucose to bloodstream
1. eat – intake glucose
2. liver condenses extra glucose to glycogen
3. blood glucose falls
4. liver hydrolyzes glycogen to glucose

Glycogen is bulky, so we store only so much:
short term energy supply
Fat is the long term energy supply.
Glucose for Energy
 enzymes break apart glucose – yielding
energy
 inadequate supply of carbohydrates
– ketone bodies (fat fragments) are an
alternate energy source during starvation
– excess ketones can lead to ketosis:
imbalance of acids in body
 minimum of 50 – 100 grams of carbs/day
are needed to avoid ketosis
Glucose Homeostasis
 maintaining an even balance of glucose is
controlled by insulin and glucagon
– insulin
 moves glucose into the blood
– glucagon
 brings glucose out of storage
maintaining balance
balanced meals at regular intervals
fiber and some fat slow the
digestive process down
glucose gets into the blood slow
and steady
1
Intestine
Maintaining
Blood
Glucose
Homeostasis
2
Pancreas
When a person eats,
blood glucose rises.
High blood glucose stimulates
the pancreas to release insulin.
Insulin
3
Insulin stimulates the uptake of glucose into cells
and storageas glycogen in the liver and muscles.
Insulin also stimulates the conversion of excess
glucose into fat for storage.
Liver
Fat cell
Muscle
Pancreas
4
As the body's cells use
glucose, blood levels decline.
5
Low blood glucose stimulates
the pancreas to release
glucagon into the bloodstream.
6
Glucagon stimulates liver
cells to break down glycogen
and release glucose into the
blood.a
Glucagon
Glucose
Insulin
Glucagon
Glycogen
s hormone epinephrine and other hormones
lucose out of storage.
Liver
7
Blood glucose begins to rise.
Imbalance
 diabetes
– after food intake, blood glucose rises and
is not regulated because insulin is
inadequate
 hypoglycemia
– blood glucose drops dramatically
 too much insulin, activity, inadequate
food intake, illness
 diet adjustment includes fiber-rich carbs
and protein
Glycemic Index
 way of classifying
food according to
their ability to raise
blood glucose
 much controversy
Sugar
 ½ comes from natural sources, ½ from
refined and added
– sucrose, corn syrup, honey
 excess can lead to nutrient deficiencies
and tooth decay
– empty calories
– sugar and starch break down in the
mouth
Sugar
 recommended intake
– added sugar = no more than 10% of energy
intake
Starch and Fiber
 diet that includes starch, fiber and natural
sugars
– whole grains, vegetables, legumes, fruits
 may protect against heart disease and
stroke
 reduces the risk of type 2 diabetes
 enhances the health of the large
intestine
 can promote weight loss
Starch and Fiber
 starch intake
– 45-65%
– 225 – 325 grams (DV is 300
grams)
– 900-1300 kcal/2000 kcal
– RDA is 130 grams
 fiber intake
– Daily Value is 25 grams/2000
kcal
Groceries
 grains: 1 serving = 15 grams
 vegetables
– ½ cup starchy = 15 grams
– ½ cup nonstarchy = 5 grams
 fruit: 1 serving = 15 grams
 milk: 1 cup = 12 grams
 meat: none or little
 legumes: ½ cup = 15 grams
Artificial Sweeteners
 help keep sugar and energy intake down
 anything we eat has FDA approval
– saccharin
– aspartame
– acesulfame potassium
– sucralose
– neotame
Sugar Replacers
 sugar alcohols
– provide bulk and sweetness
 cookies, gum, candy, jelly
– do contain minimal kcal
– low glycemic response
 absorbed slowly
– do not cause dental caries
Assignment
 Taghreed Mahmoud
 Sohila nabil hamed
Recommended text book
Manual dietetic book