Download Carbohydrates - Ukiah Adult School

Nutrition
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Energy Metabolism and
Carbohydrates
Low calorie sweeteners
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Sugar alcohols
Natural sweeteners derived from
monosaccharides
1.6 to 2.6 calories/ gram
Sorbitol
Mannitol
Xylitol
Objectives
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Define terms in the vocabulary
Describe how energy is released from carbohydrates
Estimate the daily energy requirements for young,
healthy adults at moderate activity.
State 3 factors that increase caloric requirements
Define Glycemic Response
Name sources of carbohydrates in the diet.
State uses of carbohydrates in the body
List 4 problems resulting from excess CHO intake
Define fiber and describe its use in the diet.
Objectives: Energy Metabolism
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Discuss 3 different ways the body can use
food for energy.
Describe how the body handles excess
intake of energy producing foods.
Define the difference between anabolism and
catabolism
Estimate the BMR
Discuss the importance of regular exercise.
Vocabulary
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Carbohydrates
Fiber
Insoluble fiber
Functional fiber
Absorption
Metabolism
Glycemic Index
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Energy metabolism
Anabolism
Catabolism
Basal Metabolism
Aerobic Exercise
Carbohydrates
a class of energy-yielding nutrients
that contain only carbon, hydrogen,
and oxygen, hence the common
abbreviation of CHO
 major function of carbohydrates is to
provide energy, which includes
sparing protein and preventing ketosis
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Functions
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Provide energy for cells
Supplies 4 cal/Gm
Spare protein
Prevention of ketosis
Carbohydrates
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Classifications
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Simple
Complex
Classification is based on the number of
single sugar molecules they contain
Carbohydrates: Sugars
Monosaccharide: single (mono)
molecules of sugar (saccharide)
 Disaccharide: “double sugar”
composed of 2 (di) monosaccharides
 Polysaccharide: carbohydrates
consisting of many (poly) sugar
molecules
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Monosaccharides
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Fructose, galactose and glucose
Each contains one sugar molecule
Monosaccharides
Do not require digestion before absorption
Glucose
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Glucose can be
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converted to glycogen
used to make nonessential amino acids
used for specific body compounds
converted to fat and stored in adipose
tissue
Disaccharides
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Two linked monosaccharides
Sucrose= glucose + fructose
Maltose= glucose + glucose
Lactose= glucose + galactose
Sugars: Not always a “sweet thing”
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Sugars--as well as starches--promote dental decay
by feeding bacteria in the mouth that produce an
acid that damages tooth enamel
Sugar is also a source of empty calories
The higher the intake of empty calories, the
greater the risk of an inadequate nutrient intake,
an excessive calorie intake, or both
A diet high in sugar is at risk for iron deficiency
Americans’ intake of sugar and artificial
sweeteners is rising
Sugar: Too much of a good thing
Dental caries
 Behavioral problems in children
 Obesity
 Diabetes mellitus
 Heart disease
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Most common sources of added sugar
in the American diet
Soft drinks
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Cakes, cookies, pies
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Fruit drinks and punches
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Dairy desserts such as ice cream
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Candy
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A word about HFCS
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Princeton study
High fructose corn syrup is commonly used in place
of sugar in processed foods in the USA.
The average American eats 41.5 lbs of high fructose
corn syrup per year
Soft drink consumption has doubled for females and
tripled for males since the late 1970’s
Relative sweetness of sugars
Carbohydrates: Found in every level
of the food Pyramid
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starches are most abundant in the Bread,
Cereal, Rice, and Pasta group, the
Vegetable group, and the plant foods found
in the Meat and Poultry group
natural sugars occur in the Fruit group and
in the Milk, Yogurt, and Cheese group
the apex contains sugars and other sweets
such as candy, gelatin, and soft drinks
RDA for Carbohydrates
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The RDA for carbohydrates is set as the
minimum amount needed to fuel the brain
but not an amount adequate to satisfy
typical energy needs
Most experts recommend that 45% to 65%
of total calories come from carbohydrates
Added sugars limited to 6-10% of calories
25 - 38 g of fiber are recommended daily
for adult women and men respectively
Complex Carbohydrates
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Composed of long chains of glucose
molecules
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Starch: storage form of glucose in plants
Glycogen: storage form of glucose in animals
and humans
A group name for starch, glycogen, and
fiber
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Dietary fiber: carbohydrates and lignin--natural
and intact components of plants that human
enzymes cannot digest
Fiber
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Total fiber: total fiber = dietary fiber +
added fiber
Insoluble fiber: nondigestible
carbohydrates that do not dissolve in water
Soluble fiber: nondigestable carbohydrates
that dissolve to a gummy, viscous texture
Fiber---It’s not just wool and cotton
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Insoluble
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Give texture to plant foods
Increase stool weight to “keep you regular”
Found in bran, skins, seed coverings, whole grains, dried
legumes, vegetables
Soluble
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Lower serum cholesterol
Improve glycemic control in diabetics
Found in apples, dried legumes, vegetables, oats, rice hulls
Fiber
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Functional fiber: as proposed by the
Food and Nutrition Board, functional
fiber consists of extracted or isolated
nondigestible carbohydrates that have
beneficial physiological effects in
humans
Fiber
The most popular American foods do
not represent rich sources of fiber
 Whole grains, bran cereals, dried
peas and beans, and unpeeled fruits
and vegetables are the best sources
of fiber
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Grains
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Refined grains and refined flours:
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consist of only the endosperm (middle
part) of the grain and, therefore, do not
contain the bran and germ portions
Whole grains and whole grain flours:
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contain the entire grain, or seed, which
includes the endosperm, bran, and germ
What is in a whole grain?
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Endosperm
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Bran
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Energy
Fiber, vitamins
Germ
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Vitamins, minerals
Health Benefits of Fiber
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Promotes bowel regularity
Hastens bowel transit time
Prevention of diverticular disease
Lowers cholesterol, triglycerides to improve
heart health
Help prevent certain cancers
Weight control
How to increase dietary fiber
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Choose a ready-to-eat cereal with 5 grams of fiber or
more per serving
Eat dried peas and beans two to three times/week
Replace refined grains with whole grains
Eat at least five servings of fruits and vegetables daily
Eat a variety of plant foods daily
Increase fiber intake gradually to avoid GI intolerance
Consume adequate fluid
Carbohydrate Digestion
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Majority of carbohydrate digestion occurs in the small
intestine, where disaccharides and starches are digested to
monosaccharides
Monosaccharides are absorbed through intestinal mucosal
cells and transported to the liver through the portal vein
In the liver, fructose and galactose are converted to glucose
The liver releases glucose into the bloodstream
Fiber is fermented by bacteria in the colon to produce water,
gas, short-chain fatty acids and other compounds.
Enzymes
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Amylase
Maltase
Sucrase
Lactase
Absorption
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Glucose, fructose and galactose are
abosorbed through intestinal mucosa
Travel to liver via portal vein
Soluble fiber slows the absorption of glucose
Unabsorbed starch and fiber excreted in
stool
Metabolism
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Fructose and galactose converted to glucose
Liver releases glucose into blood
Hormones maintain constant BG
Insulin
Glycogen
Glucocagon
Non-essential amino acids
Fat
Carbohydrates and serum glucose
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Glycemic response:
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the effect a food has on the blood
glucose concentration
how quickly the glucose level rises, how
high it goes, and how long it takes to
return to normal
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Glycemic index:
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a numeric measure of the glycemic
response of 50 g of a food sample
the higher the number, the higher the
glycemic response
Glycemic index and exercise
endurance
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The types of carbohydrate eaten before,
during, and after prolonged exercise influences
an athlete’s endurance
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low glycemic index carbohydrates – eat before
prolonged exercise
moderate to high glycemic index carbohydrate
foods – eat during long distance events to ensure
adequate glucose availability
high glycemic index foods – eat after exercise to
enhance glycogen repletion compared to low
glycemic index carbohydrates
Artificial Sweetners
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Artificial sweeteners: synthetically made
sweeteners that do not provide calories
Acceptable Daily Intake (ADI):
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estimated amount of artificial sweetener per
kilogram of body weight that can be safely
consumed every day over lifetime without risk
usually reflects an amount 100 times less than the
maximum level at which no observed adverse
effects have occurred in animal studies
Artificially sweet
Be choosy about carbohydrate
calories
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Eat a diet based on whole grain breads and
cereals with plenty of fruits, vegetables, and
dried peas and beans---not an ad lib intake
of products made with white flour and white
sugar
High carbohydrate should be achieved with
wholesome, unprocessed foods for
optimum health benefits and weight
management
Lower your sugar consumption
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It's been suggested that the supposed link between high fructose corn syrup
and obesity is not due to the high fructose corn syrup itself, but to the
increasing consumption of sweeteners in general, especially soft drinks. The
USDA recommends that a person with a 2000 calorie, balanced diet should
consume no more than 32 g (8 tsp) of added sugar per day. Here are some
sweet foods and the percentage of the daily recommended amount of
sweeteners they provide:
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typical cup of fruit yogurt - 70%
cup of regular ice cream - 60%
12-ounce Pepsi - 103%
Hostess Lemon Fruit Pie - 115%
serving of Kellogg's Marshmallow Blasted Froot Loops - 40%
quarter-cup of pancake syrup - 103%
Cinnabon - 123%
large McDonald's Shake - 120%
large Mr. Misty Slush at Dairy Queen - 280%
Burger King's Cini-minis with icing - 95%
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Energy
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relatively abstract in that it cannot be defined by its
size, shape, or mass
neither created nor destroyed but changes from one
form to another without being used up
extracted from nutrients
stored within cells as a source of immediate fuel
larger amounts of energy are available in glycogen
and fat tissue to fuel activity of longer duration
synonymous with calories
Energy Metabolism
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a dynamic process that constantly changes with the
influx of nutrients, the availability of stored energy, and
the demands of fueling activity
how energy from carbohydrates, proteins, and fats is
extracted and used.
encompasses the processes of anabolism and
catabolism that occur continuously as the body uses
energy to synthesize compounds or extracts energy
from the breakdown of nutrients from food or body
storage
Anabolism
an energy-us ing proc es s that oc c urs c onti nuous ly in al l people as c ell s or subs tanc es are replac ed after normal wear and tear
reas s embles nutrients i nto c ompounds for s torage
Regardl es s of the s ourc e, cal ories eaten i n exc ess of need are c onverted to fatty ac i ds and s tored as body fat
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Catabolism
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breakdown of large molecules into smaller ones
glycogen is broken down into glucose
protein into amino acids
triglycerides into glycerol and fatty acids
These four basic units catabolize into smaller substances and ultimately into energy
This energy is trapped in adenosine triphosphate (ATP) and stored in every cell until needed
Whether from food or body storage, glucose, amino acids, glycerol, and fatty acids all eventually enter the tricarboxylic acid cycle (Krebs’ cycle) and
electron transport chain to yield energy as needed
Nutrient availability
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Nutrients broken down into pyruvate, namely
glucose, glycerol, and glucogenic amino acids, can
be synthesized into glucose as needed by the body
Nutrients broken down into acetyl CoA, namely
fatty acids and ketogenic amino acids, cannot be
resynthesized into glucose and so cannot fuel
glucose-requiring cells of the brain, nervous tissue,
and red blood cells when glucose from food or
glycogen is unavailable
Glucose availability
B reaki ng down body prot ein to yield glucose i s expensi ve because onl y about half of ami no acids can actually be converted to gl ucose
Y et it i s more ef fici ent compared to the small amount of glucose available from glycerol in stored tri glycerides (5% of the triglyceri de molecule is glycerol)
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Fasting
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prolonged fasting, the brain and nervous
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body protein catabolism continues
adaptive mechanism is that metabolism
Aerobic metabolism vs. Glycolysis
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Cells’ immediate source of fuel is stored in ATP, which
is supplemented with a small supply of creatine
phosphate
Neither requires oxygen to be burned
Glucose is the only fuel that can be burned without
oxygen through the process of glycolysis
Glycolysis extracts only a small amount of the total
available energy from glucose
Aerobic metabolism includes the TCA cycle and the
electron transport chain
It yields the maximum amount of available energy
Activity
Body uses a mixture of fuels at rest and at work
 As duration of activity increases, amount of fat
burned increases in an attempt to conserve body’s
supply of glycogen
 As intensity of activity increases, amount of glucose
burned increases because glucose is the only fuel
that can be metabolized anaerobically
 This anaerobic metabolism manifests in
breathlessness that occurs with vigorous exercise
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Basal Metabolism
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Amount of calories required to fuel
involuntary activities of the body at
rest after a 12-hour fast
In essence, it is the caloric cost of
staying alive
Calculating BMR
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Multiply healthy weight (in pounds)
by 10 for women and 11 for men; or
 2) Harris-Benedict equation:
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Males: 66 + (13.7 x W) + (5 x H) – (6.8 x A)
Females: 655 + (9.6 x W) + (1.7 x H) – (4.7 x A)
 Where
W = actual weight in kg
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H = height in cm
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A = age in years
BMR is influenced by numerous
factors
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Body composition--lean vs. fat tissue
Growth
Hormones
Fever
Height
Environmental temperature
Starvation, fasting, and malnutrition
Weight loss from dieting
Stress
Certain drugs
Total daily calorie expenditure
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equals the amount of calories spent on voluntary
activities (physical activity) and on involuntary
activities (basal metabolism)
For most Americans, basal metabolism
represents 60% to 70% of total calories burned
Thermic effect of food is the cost of digesting,
absorbing, and metabolizing food
At about 10% of total calories consumed, it is a
small part of total energy requirements
Estimating Total Calorie Expenditure
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Choose the category that fits activity level
Multiply BMR by:
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1.2 for sedentary
1.3 for light activity
1.4 for moderate activity
1.5 for high activity
Physical activity
 The
vast majority of Americans do not
get the recommended amount of
physical activity
 Benefits of physical activity are dosedependent and range from significant
health benefits to weight management
to optimal physical fitness
Exercise
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In the short term, exercise leads to
modest weight loss if calories are
not also restricted
In the long term, exercise promotes
weight loss by promoting fat loss
and preventing loss of muscle,
which contributes to metabolic rate
Maximal heart rate
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approximately 220 minus the
individual’s age
 Target heart rate is obtained by
multiplying maximum heart rate by the
desired percent.
For optimum physical fitness:
Engage in moderate to high intensity aerobic
exercise at 60 to 90% maximal heart rate three to
five times/week, with each session lasting 20 to 60
minutes plus additional time for warm-up and cooldown
 Perform strength training exercises 2 to 3 times per
week with each session lasting at least 15 minutes
 Do stretching exercises at least 3 to 4 times/week,
preferably every day, to increase range of motion
and flexibility
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How to burn 150 calories
(based on a 150-pound person):
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Pedal a stationary bicycle for 20 minutes
Practice fast dance steps for 24 minutes
Work in the garden for 27 minutes
Walk briskly (3.5 mph) for 33 minutes
Clean the house for 38 minutes
Suggestions for increasing
activity:
 Find
something enjoyable
 Use the buddy system
 Spread activity over the entire day if desired
 Start slowly and gradually increase activity
 Move more
 Keep an activity log
Activity, exercise and weight
Use activity and exercise to manage weight
 Exercise is vital to maintain weight loss
 Aim to increase energy expenditure by 10002000 calories per week
 Don’t expect pounds to melt away
 Remember that what is important is burning
calories, not the actual type of fuel used
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