Transcript cabohydratesx

Chapter 3
The
Carbohydrates:
Sugar, Starch
and Fiber
© 2007 Thomson - Wadsworth
Ask Yourself
1. Fruit sugar (fructose) is less fattening than table
sugar (sucrose).
2. Foods high in complex carbohydrate (starch and
fiber) are good choices when you are trying to lose
weight.
3. People with diabetes should never eat sugar.
4. The primary role of dietary fiber is to provide energy.
5. The brain demands the sugar glucose to fuel its
activities.
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Ask Yourself
6. Honey and refined sugar are the same as far as the
body is concerned.
7. Of all the components of foods that increase one’s
risk of diseases, sugars are probably the biggest
troublemakers.
8. Breads that are brown in color have more fiber than
white bread.
9. Some foods labeled sugar-free actually contain
calorie bearing sugars.
10. Artificial sweeteners are safe to use in moderation.
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Carbohydrate Basics
• The primary role of carbohydrates is to
provide the body with energy (calories).
• Carbohydrates are the preferred fuel for
the brain and nervous system.
• Carbohydrates are the ideal fuel
compared to other alternatives:
 Less expensive than protein.
 High-fat diets are associated with chronic
disease.
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© 2007 Thomson - Wadsworth
Carbohydrate Basics
• Carbohydrates: compounds made of single
sugars or multiples of them and composed of
carbon, hydrogen, and oxygen atoms.
 carbo = carbon (C)
 hydrate = water (H2O)
• Complex carbohydrates: long chains of
sugars (glucose) arranged as starch or fiber.
Also called polysaccharides.
 poly = many
 saccharides = sugar unit
• Simple carbohydrates (sugars): the single
sugars (monosaccharides) and the pairs of
sugars (disaccharides) linked together.
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Carbohydrate Basics
• Carbohydrate-rich foods are
obtained almost exclusively from
plants.
Milk is the only animal-derived food
that contains significant
carbohydrate.
• All carbohydrates are composed of
single sugars, alone or in various
combinations.
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© 2007 Thomson - Wadsworth
Simple Carbohydrates
• Glucose is made of
water and carbon
dioxide.
 Plants use energy
from the sun to
synthesize it.
• The atoms in a
glucose molecule can
be rearranged by
plants to form
fructose, too.
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Simple Carbohydrates
• Single Sugars - Monosaccharides:
 Glucose: (GLOO-koce) the building block of
carbohydrate; a single sugar used in both
plant and animal tissues as quick energy. A
single sugar is known as a monosaccharide.
• mono = one
 Fructose: (FROOK-toce) fruit sugar—the
sweetest of the single sugars.
 Galactose: (ga-LACK-toce) another single
sugar that occurs bonded to glucose in the
sugar of milk.
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Simple Carbohydrates
• Double Sugars - Disaccharides:
 Sucrose: (SOO-crose) a double sugar
composed of glucose and fructose. A double
sugar is known as a disaccharide.
• di = two
 Maltose: a double sugar composed of two
glucose units.
 Lactose: a double sugar composed of
glucose and galactose; commonly known as
milk sugar.
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Simple Carbohydrates
Added Sugars:
• Sugar cane and sugar
beets are purified to
make sucrose.
• Food examples include
white (table) sugar,
brown sugar, powdered
sugar.
• Sucrose is common in
sweets.
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Simple Carbohydrates
• Enzymes: protein
catalysts. A
catalyst facilitates a
chemical reaction
without itself being
altered in the
process.
 (Proteins are
discussed in Chapter
5; digestive
enzymes in
Appendix A.)
• Lactose intolerance:
inability to digest
lactose as a result of a
lack of the necessary
enzyme lactase.
 Symptoms include
nausea, abdominal
pain, diarrhea, or
excessive gas that
occurs anywhere from
15 minutes to a couple
of hours after
consuming milk or milk
products.
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Complex Carbohydrates
• Starch: All starchy foods
are plant foods.
• Sources of starch
include:
 Seeds such as grains, peas
and beans.
 Legumes including dried
beans, lentils and
soybeans.
 Root vegetables (yams)
and tubers (potatoes).
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Complex Carbohydrates
• Starch: a plant polysaccharide
composed of hundreds of glucose
molecules, digestible by human beings.
• Polysaccharide: a long chain of 10 or
more glucose molecules linked
together; the chains can be straight or
branched; another term for complex
carbohydrates.
 Shorter carbohydrate chains composed of 3
to 10 glucose molecules are called
oligosaccharides.
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Complex Carbohydrates
• Staple grain: a
grain used frequently
or daily in the diet.
Examples include:
 Corn in Mexico
 Rice in Asia
 Wheat in Canada,
Europe and USA
 Millet, rye, barley, and
oats
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Complex Carbohydrates
• Refined: refers to
the process by which
the coarse parts of
food products are
removed.
 For example, the
refining of wheat into
flour involves
removing three of the
four parts of the
kernel—the chaff, the
bran, and the germ—
leaving only the
endosperm.
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The Wheat Kernel: A Whole Grain
• Germ: the nutrient-rich and
fat-dense inner part of a
whole grain.
• Endosperm: provides
energy; contains starch
grains embedded in a protein
matrix.
• Bran: the fibrous protective
covering of a whole grain and
source of fiber, B vitamins,
and trace minerals.
• Husk: (chaff) the outer,
inedible covering of a grain.
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Complex Carbohydrates
• Whole grain: refers to a grain that is milled in its
entirety (all but the husk), not refined.
 Whole grains include wheat, corn, rice, rye, oats, amaranth,
barley, buckwheat, sorghum, and millet; two others—bulgur
and couscous—are processed from wheat grains.
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Complex Carbohydrates
• Enriched: refers to a process by which the
B vitamins thiamin, riboflavin, niacin, folic
acid, and the mineral iron are added to
refined grains and grain products at levels
specified by law.
• Fortified foods: foods to which nutrients
have been added. Typically, commonly eaten
foods are chosen for fortification with added
nutrients to help prevent a deficiency of a
nutrient (iodized salt, milk with vitamin D) or
to reduce the risk of chronic disease (juices
with added calcium).
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© 2007 Thomson - Wadsworth
Eat Well Be Well
Whole Grains for Health
1. Count to Three
2. Keep It Varied
3. Check the Label
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Complex Carbohydrates
• Fiber: the indigestible residues of food,
composed mostly of polysaccharides. The best
known fibers are cellulose, hemicellulose,
pectin, and gums.
 Comes from the supporting structures of plants:
leaves, stems and seeds.
 Cannot be broken down by human digestive
enzymes although some may be broken down by
bacteria residing in the digestive tract.
 Fiber has few if any calories because it is not
digested.
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Complex Carbohydrates
• Insoluble
fiber includes
the fiber types
called cellulose,
hemicellulose,
and lignin.
• Insoluble fibers
do not dissolve
in water.
• Soluble fiber includes
the fiber types called
pectin, gums, mucilages,
some hemicelluloses, and
algal substances (for
example, carageenan);
soluble fibers either
dissolve or swell when
placed in water.
 Psyllium seed husk is
an ingredient in certain
cereals and bulkforming laxatives and
contains both soluble
and insoluble
properties.
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Complex Carbohydrates
• Whole food: a food
that is altered as little
as possible from the
plant or animal tissue
from which it was
taken—such as milk,
oats, potatoes, or
apples.
 The more a food
resembles the original,
farm-grown product, the
more nutritious it is likely
to be.
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© 2007 Thomson - Wadsworth
We are advised to
increase our intakes of
complex carbohydrates.
Choose plenty of whole
foods like this…
…and fewer foods like
these—foods that no
longer resemble their
original farm-grown
products.
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Added Sugars: Use
Discretion
• Choose and prepare foods with
little added sugar (Dietary Guidelines).
• Choose most often the naturally
occurring sugars (DRI).
• For those who meet their nutrient
needs, maintain a “healthy body
weight” and still need additional
calories --maximum intake = 25%
or less for added sugars (DRI).
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Added Sugars: Use
Discretion
• Discretionary calories-small amounts of added
sugars allowed within
MyPyramid calorie
allowance:
Consistently build your
diet using nutrientdense foods, low in
added sugars





3 tsp. for 1,600 calories
5 tsp. for 1,800 calories
8 tsp. for 2,000 calories
9 tsp. for 2,200 calories
12 tsp. for 2,400 calories
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Added Sugars: Use
Discretion
• Reduce the
incidence of
dental caries by
practicing good
oral hygiene and
consuming sugarand starchcontaining foods
and beverages
less frequently
(Dietary Guidelines).
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How the Body Handles
Carbohydrates
• Digestive system: the body system
composed of organs and glands associated with
the ingestion and processing of food for
absorption of nutrients into the body.
• Digestion: the process by which foods are
broken down into smaller absorbable products.
• Absorption: the passage of nutrients or
substances into cells or tissues; nutrients pass
into intestinal cells after digestion and then into
the circulatory system (for example, into the
bloodstream).
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How the Body Handles
Carbohydrates
• Glycogen (GLY-co-gen): a
polysaccharide composed of chains of
glucose, manufactured in the body and
stored in liver and muscle.
As a storage form of glucose, liver
glycogen can be broken down by the
liver to maintain a constant blood
glucose level when carbohydrate
intake is inadequate.
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© 2007 Thomson - Wadsworth
When a person eats, blood glucose
rises. High blood glucose stimulates
the pancreas to release insulin. Insulin
serves as a key for entrance of blood
glucose into cells. Liver and muscle
cells store the glucose as glycogen.
Excess glucose can also be stored as
fat.
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Later, when blood glucose is low, the
pancreas releases glucagon, which
serves as the key for the liver to break
down stored glycogen into glucose and
release it into the blood to raise blood
glucose levels
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How the Body Handles
Carbohydrates
• Insulin: a hormone secreted by the
pancreas in response to high blood glucose
levels; it assists cells in drawing glucose from
the blood.
• Glucagon (glue-cuh-gon):a hormone
released by the pancreas that signals the liver
to release glucose into the bloodstream.
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How the Body Handles
Carbohydrates
• Glycemic index (GI): a scale that ranks
carbohydrate-containing foods by how much
they raise blood glucose levels compared to a
standard food such as glucose or white bread.
The glycemic load (GL) is a measure of the
extent to which blood glucose is raised by a
given amount of carbohydrate-containing food.
• Glycemic effect: the effect of food on a
person’s blood glucose and insulin response –
how fast and high the blood glucose raises and
how quickly the body responds by normalizing.
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Diabetes
• Diabetes (dye-uh-BEET-eez): a
disorder (technically termed diabetes
mellitus) characterized by insufficiency
or relative ineffectiveness of insulin,
which renders a person unable to
regulate the blood glucose level
normally.
 Type 1 diabetes
 Type 2 diabetes
 Gestational diabetes (see Chapter 11)
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© 2007 Thomson - Wadsworth
Prevalence of Diagnosed
Diabetes by State
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Hypoglycemia & Diabetes
• Hypoglycemia (HIGH-po-gligh-SEEM-
eeuh): an abnormally low blood glucose
concentration—below 60 to 70 mg/100 mL.
• Ketosis: abnormal amounts of ketone
bodies in the blood and urine; ketone bodies
are produced from the incomplete breakdown
of fat when glucose is unavailable for the brain
and nerve cells.
• Hyperglycemia: an abnormally high blood
glucose concentration, often a symptom of
diabetes.
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A Look at the Glycemic
Effect of Foods
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Check your diabetes risk at…
• http://www.diabetes.org/risktest.jsp?WTLPromo=HOME_risktes
t&vms=207048605236
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Sugar and Health
• Research studies have not shown a direct
link between sugar and obesity, diabetes,
heart disease, hyperactivity in children or
criminal behavior.
• Diluted naturally occurring sugars found in
milk and fruits should not be confused with
concentrated refined sugar foods, such as
table sugar, honey, and corn syrup. These
concentrated sweets should be used in
moderation, so as not to displace needed
nutrients.
• Empty-calorie foods: a phrase used
to indicate that a food supplies calories but
negligible nutrients.
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Keeping a Healthy Smile
• Dental caries – decay of the teeth, or
cavities
• Dental plaque – a colorless film, consisting of
bacteria and their by-products, that is
constantly forming on the teeth
• Periodontal disease – inflammation or
degeneration of the tissues that surround and
support the teeth
• Nursing bottle syndrome – decay of all the
upper and sometimes the back lower teeth
that occurs in infants given carbohydratecontaining fluids when they sleep, or to carry
around and sip all day
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• HOW DID YOU DO?
 The more often you choose the items listed above, the
higher your diet is likely to be in sugars.You may need to
cut back on sugar-containing foods, especially those you
checked as “3 to 5 times a week” or more.This does not
mean totally eliminating these foods from your diet.
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Check Your Diet for Fiber
Fiber…
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Concerns with Artificial
Sweeteners
• Does saccharin cause cancer?
• Does aspartame cause headaches?
• Aspartame and phenylketonuria
(PKU)
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To reach the FDA’s limit, a 150-pound adult would
have to consume about 19 12-ounce cans of diet
soda pop or 97 packets of Equal.
A 40-pound child would have to consume four 12ounce cans of diet soft drinks or 24 packets of
Equal.
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Artificial Sweeteners &
Sugar Alcohols
• Splenda’s popularity
• Artificial sweeteners and weight
loss
• Sugar substitutes and tooth decay
• Sugar-free chewing gum
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