Transcript Chapter 5 Carbohydrates

Chapter 5 Carbohydrates
Objective
1. Describe the three types of carbohydrates
Carbohydrates
What comes to mind when you
think of carbohydrates?
Carbohydrates
carbohydrates: one of the six classes of nutrients that
includes sugars, starches and fibers. The body’s main
source of energy
Except for the natural sugar in milk, nearly
all carbohydrates come from plant sources.
Carbohydrates
Three Types of Carbohydrates
•Monosaccharides
•Disaccharides
•Polysaccharides
Carbohydrates
Carbohydrates are made of
three common chemical
elements:
•Carbon
•Hydrogen
These elements are bonded
together to form saccharides,
or sugar units
•Oxygen
These elements can be combined in several
ways—the arrangement of the elements
determines the type of sugar unit.
Monosaccharides
•Carbohydrates composed of single sugar
units
•Are the smallest carbohydrate molecules
Three Types of
Monosaccharides
•Glucose
•Fructose
•Galactose
Monosaccharides
Glucose
•Also known as blood sugar because it
circulates in the bloodstream
•It is the body’s source of energy
Fructose
•Has the sweetest taste
•Occurs naturally in fruits and honey
Galactose
•Does not occur alone as a
monosaccharide in foods
•It is bonded to glucose—together these 2
monosaccharides form the sugar in milk
Disaccharides
•Made up of two sugar units
•The body splits disaccharides into
monosaccharides during digestion
Three Types of Disaccharides
•Sucrose
•Maltose
•Lactose
Disaccharides
Sucrose
•Sugar you use in recipes or add to foods
•Made up of one glucose molecule and
one fructose molecule that are bonded
together
Examples: beet sugar, cane sugar, molasses and maple sugar
Disaccharides
Lactose
•Found in milk
•Made up of one glucose molecule and one
galactose molecule bonded together
•Serves as a source of energy for breastfed infants
Maltose
•Made up of two glucose molecules that are bonded
together
•Formed during the digestion of starch
•Can also be found in certain grains such as malt
Disaccharides
Note:
All the mono-and disaccharides
are collectively referred to as
sugars.
Polysaccharides
•Carbohydrates that are made up of many
sugars
•Must be broken down during digestion
Types of Polysaccharides
•Fibers
•Starches
Polysaccharides
Starch
•Storage form of energy in plants
•Made of many glucose molecules that
are bonded together
Examples: grain products (breads &
cereals), starchy vegetables (corn, potatoes
& legumes)
Polysaccharides
Fibers
•Polysaccharides that are make up the tough,
fibrous cell walls of plants
•Found only in plant foods
•Human digestive enzymes cannot digest fibers,
but bacteria in the digestive tract can break
down some fibers—therefore, fibers provide
almost no energy
Examples: cellulose, gums and pectin
Simple vs. Complex Carbohydrates
Simple Carbohydrates
•Mono-and disaccharides
•Foods that are high in simple sugars
Examples: table sugar, candy, syrups and soft drinks
Simple vs. Complex Carbohydrates
Complex Carbohydrates
•Polysaccharides
•Foods that are high in starch and fiber
Examples: breads, cereals, rice, pasta & vegetables
Simple vs. Complex Carbohydrates
Choosing food sources of complex
carbohydrates and fewer sources of
simple carbohydrates has health and
nutrition benefits.
Stayed tuned to learn why!!!
Hint……
Pop Quiz
STUDY!!!!!!!!!!!!!
Objectives
1. List the functions of carbohydrates.
2. Explain how the body uses carbohydrates.
Review
Take 5-10 minutes to review your
notes from yesterday for a pop
quiz!!!
Objectives
1. List the functions of carbohydrates.
2. Explain how the body uses carbohydrates.
Four Key Functions of Carbohydrates
•Provide energy
•Spare proteins
•Assist in the breakdown of fats
•Provide bulk in the diet
Functions of Carbohydrates:
Provide Energy
•your body’s top priority is to provide enough energy for
all cellular activities needed to sustain life
•carbohydrates are the preferred source of energy
WHY?
Because your body can use them
efficiently as a fuel supply
If your diet does not provide enough carbohydrates, your
body will
draw mainly upon proteins for fuel needs
Functions of Carbohydrates:
Spare Proteins
Background Information:
•if needed, your body can use proteins as an energy
source
•your body is less efficient in using proteins
•if you eat too little carbohydrates, your body will use
proteins for its major functions
By eating adequate amounts of
carbohydrates, you spare the proteins—
this means you allow the proteins to be
used for their more vital roles
Functions of Carbohydrates:
Break Down Fats
If the diet is too low in carbohydrates, the body
cannot completely break down fats
Incompletely broken down fats form compounds
called ketone bodies
Ketone bodies collect in the blood stream and
become acidic—causing damage to cells and
organs (ketosis)
Functions of Carbohydrates:
Provide Bulk in the Diet
•fiber is the carbohydrate responsible
for this task
•fiber helps promote normal digestion
and elimination of body wastes
•fiber swells and makes you feel full
•fiber also slows the rate at which the
stomach empties
Functions of Carbohydrates:
Provide Bulk in the Diet
Benefits of Fiber in the Diet:
•Prevent appendicitis
•Decrease risk of heart and artery disease
•Lower risk of colon cancer
•Controls diabetes
soluble fiber: dissolves in water and develops a gel-like
consistency—it helps lower blood cholesterol levels
Example: oat bran, legumes
insoluble fiber: does not dissolve in water—it helps
reduce the risk of certain cancers
Example: wheat bran and whole grains
How Your Body Uses Carbohydrates
•all carbohydrates must in the form of
glucose for your cells to use them as
energy sources
•to get them in this form, your
digestive systems first breaks down
all poly-and disaccharides into
monosaccharides
How Your Body Uses Carbohydrates
The monosaccharides are small enough to move
across the intestinal wall into the blood
They travel via the blood to the liver
Any fructose and galactose in the blood is
converted to glucose in the liver
Objectives
Explain how your body uses carbohydrates.
2. Use food labels to meet your carbohydrate needs.
1.
Pop Quiz
1. Besides providing energy, name 1 function of
carbohydrates.
2. T/F All carbohydrates must in the form of glucose
for your cells to use them as energy sources.
3. T/F Your digestive systems does not have to
break down all poly-and disaccharides into
monosaccharides to use as energy.
4. Monosaccharides travel via the blood to the _____.
5. Any fructose and galactose in the blood is
converted to _____ in the liver.
Bonus: Why are carbohydrates the preferred source of
energy?
How Your Body Uses Carbohydrates
When the amount of glucose in the blood rises, a
hormone called insulin is released from the
pancreas.
hormones: chemicals produced in the body and
released into the bloodstream to regulate specific
body processes
insulin: helps the body decrease blood glucose back
to a normal level
How Your Body Uses Carbohydrates
Insulin triggers body cells to burn glucose for
energy
Insulin also causes muscles and the liver to
store energy
If the cells do not have immediate energy needs,
they store the glucose—the glucose is converted to
glycogen
How Your Body Uses Carbohydrates
glycogen: the body’s storage form of glucose
•2/3 is stored in your muscles for using
during muscular activity
•1/3 is stored in the liver for use by the rest
of the body
How Your Body Uses Carbohydrates
•your liver can store only a limited
amount of glycogen
•if you eat more carbohydrates than your
body can immediately use or store as
glycogen, your liver will convert the
excess carbohydrates into fat
Note: fat stores cannot be converted back into
glucose
Meeting Your Carbohydrate Needs
Two Categories of Sugars
•Sugars that occur naturally in foods
•Sugars added to foods at the table or
during processing
Meeting Your Carbohydrate Needs: Sugars
Sugars that occur naturally in foods
•Generally accompanied by other nutrients in
foods—therefore they do not cause great concern
among nutrition experts
Examples: lactose in milks and fructose in fruit
Meeting Your Carbohydrate Needs: Sugars
Sugars added to foods at the table or during processing
•Sometimes called refined sugars
•They come from such sources as sugar cane, sugar beets and corn
•Refined sugars function as more than sweetening agents—they are
added to increase bulk or aid in browning
refined sugars: carbohydrate sweeteners that are separated from
their natural sources for use as food additives
Meeting Your Carbohydrate Needs: Sugars
What foods are full of refined sugars?
•Many processed foods are high in added sugars—an
excellent source of simple carbohydrates, but contributes
no other nutrients to foods (increases calories without
increasing nutrients).
•Reduced fat and fat-free products are high in added
sugars
**Manufacturers add sugar when removing fat
Meeting Your Carbohydrate Needs:
Starches
•Starches are the preferred source of fuel for
your diet.
•Your body can burn them efficiently for energy
and they have greater satiety value than simple
sugars.
•Many starchy foods are also excellent sources
of vitamins, minerals and fiber.
Meeting Your Carbohydrate Needs: Fiber
Determining fiber needs
•Take your age and add 5 to determine how many
grams of fiber you should include in your diet daily
Example: if you are 15 years old,
15+5= 20 grams of fiber per day
Use this formula to age 20, then aim for 25 to 35
grams of fiber per day
Meeting Your Carbohydrate Needs: Fiber
How to increase your fiber intake
•Choose whole grain products
•Use fiber supplements
supplement: a concentrated source of a nutrient, usually in a pill,
liquid or powder form
Increase your intake of fiber slowly and drink
plenty of water.
Using Food Labels to Meet Your
Carbohydrate Needs
Grams of sugars listed on a Nutrition Facts panel
include both naturally occurring and added
sugars—you need to do some further reading to
identify foods that are high in refined sugars.
•Read list of ingredients on label—ingredients are listed in order of
weight, with the most predominant ingredient being listed first.
•Only added sugars will be listed as ingredients.
•Check to see if more than one type of sugar is listed—these are both
indications that a product is high in refined sugars.
Using Food Labels to Meet Your
Carbohydrate Needs
Examples of refined sugars
brown sugar
invert sugar
corn sweetener
sucrose
corn syrup
lactose
dextrose
maltose
fructose
honey
glucose
molasses
sugar
Health Questions Related to
Carbohydrates
Are starchy foods fattening?
•Gram per gram, carbohydrates have the same amount of
calories (4) as protein and less than half the calories of fat (9)
•People think starchy foods are fattening because how they are
served
Example: potato, pasta
Health Questions Related to Carbohydrates
Is sugar a hazard to your teeth?
•There is a clear connection between sweets and dental caries
(tooth decay).
•People who eat more sugar are likely to have a higher
incidence of tooth decay HOWEVER starches can promote
tooth decay also.
Bacteria in the mouth feed on carbohydrates to form a sticky
substance called plaque that clings to teeth—as the bacteria grows,
they produce acid that eats away the protective tooth enamel,
forming pits in the teeth. In time, these pits can deepen into cavities.
Health Questions Related to Carbohydrates
The risk of tooth decay depends on two main
factors:
•the type of food you eat
•when you eat it
Sticky foods tend to cling to teeth making them more harmful than foods
that are quickly swallowed and removed from contact with the teeth.
Sugars and starches eaten between meals tend to be more harmful
because they tend to remain in the mouth for longer periods.
Objective
1. Evaluate the role of carbohydrates in a variety of health issues.
Review
What is the body’s
storage form of
glucose?
Your liver will convert
excess carbohydrates
into _____.
What are supplements?
What hormone is released
when glucose levels in the
blood rise?
What foods are
full of refined sugars?
Why?
What is another word for
tooth decay?
Health Questions Related to Carbohydrates
Does sugar cause hyperactivity?
hyperactivity: a condition in which a person
seems to be in constant motion and is easily
distracted
•Researchers have conducted many studies but
have found NO proof that consuming sugars
causes behavior changes in most people.
•Sugar only gives children energy needed to fuel
activity.
Health Questions Related to Carbohydrates
Is sugar addictive?
•Some people seem to crave sweets all the time—some believe this type
of craving qualifies as an addiction, or habitual need.
•Experiments have shown that if animals have a poorly balanced diet,
they will eat excessive amounts of sugar.
•Research has shown people are born with a preference for sweet-tasting
foods.
•Researchers think the need for sugar is more psychological than
physiological—in other words, people eat sweets because they enjoy
them, not because they are addicted to them.
Diabetes
diabetes mellitus: a lack of or an inability to use the hormone insulin
sugar and starch convert to glucose
which enters the bloodstream
insulin regulates the blood glucose level by
stimulating cells to pull glucose from the
bloodstream
when the body does not make enough insulin or fails
to use insulin correctly, glucose builds up in the
bloodstream
Diabetes
Two types of diabetes
Type I or insulin-dependent diabetes—the pancreas is not able to
make insulin
•Occurs most often in children and young adults
•must use insulin injections
Type II or non-insulin-dependent diabetes—body cells do not
respond well to the insulin the pancreas makes
•More common
•Occurs in adults over 40
•Can be controlled with diet
Diabetes
Symptoms of Diabetes
•Excessive hunger and thirst accompanied by weakness,
irritability and nausea
•Changes in eyesight
•Slow healing of cuts
•Drowsiness
•Numbness in legs, feet or fingers
Hypoglycemia
hypoglycemia: a low blood glucose level
an overproduction of insulin causes blood sugar to drop
sharply 2-4 hours after eating a meal
the CNS depends on a
constant supply of glucose
from the blood
when sugar is too low, physical symptoms appear—sweating,
shaking, headache, hunger and anxiety
Lactose Intolerance
lactose intolerance: an inability to digest lactose,
the main carbohydrate in milk
•This condition is caused by a lack of the digestive
enzyme lactase, which is needed to break down
lactose.
•People who are lactose intolerant may experience gas,
cramping, nausea and diarrhea when they consume
dairy products.
•Occurs more often among nonwhite populations and
tends to develop as people age.