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NUTRITION
NUTRIENTS
Substances contained in food that an organism
needs to function properly, to grow, to repair
itself, and to supply the organism with energy
REASONS FOR EATING
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Physical need
Environment/Culture ex. Movies,
Religion, family gatherings
Emotions
Hunger: natural drive that protects the
organism from starvation
• Appetite: a desire to eat rather than a
need to eat
• Nutrition: process by which the body takes
in and uses food
CARBOHYDRATES
• Starches and sugars found in foods
• Formed through a condensation reaction
where water is released by joining the
hydroxyl group from one sugar to the
hydrogen of the hydroxyl group of another
sugar molecule
• Release of water is also called hydrolysis
or dehydration
CARBOHYDRATES
• Compounds containing carbon,
hydrogen, and oxygen atoms
• Two Types
1. Monosaccharide:
• 5- or 6-carbon simple sugar
• Open chain or cyclic
• Monomers that bond to form
polymers (more complex)
GLUCOSE
CARBOHYDRATES
• Two Types
2. Disaccharide:
• Two monosaccharide linked together by
condensation reaction (H + OH → H2O)
• Examples –
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Fructose (fruits)
Lactose (milk)
Maltose (grains)
Sucrose (table sugar)
DISACCHARIDE FORMATION
CARBOHYDRATES
• Polysaccharides
– Polymers of simple sugars
– AKA complex carbohydrates
– Examples
• Starch (short-term energy storage in plants)
• Cellulose (cell walls in plants → fiber)
• Glycogen (short-term energy storage in animals)
SOURCES OF CARBOHYDRATES
• Complex Carbs
– Must be converted to glucose to provide energy
– When too many are eaten, are converted to fat
– Sources: grains, seeds, nuts, legumes, tubers
(potatoes, yams, cassava, taro)
• Fiber
– Cannot be digested but is important for movement of
wastes
– May reduce risk of some cancers and heart disease
– Sources of fiber: whole grain, bran, brown rice
oatmeal, corn
CARBOHYDRATES and HEALTH
• 60% Calories from
carbohydrates
recommended
• Provide most of the
body’s energy
• Supply 4 Cal/g
• Sources: grains,
fruits, vegetables
PROTEIN FORMATION
• Synthesized when the hydroxl group (–OH)
of one amino acid combines with a
hydrogen from the amine group (–NH2 ) of
another amino acid
• Water is released as the protein is formed
• Consequently, called condensation reaction
PEPTIDE BOND
• Bond formed when two amino acids combine to
form an amide
• Dipeptide
Proteins – Major structural components of living
things.
• Major structural components of living things
• Organic polymers are made of amino acids
(multiple repeating units)
• Made from elements: C, H, O, N, and S
• The amino acid is the basic building block or
monomer
• Amine = NH2 Acid = COOH
PROTEINS and HEALTH
• Made from long chain (50–1000) of amino
acids.
• 20 different amino acids form all necessary
proteins
• Eight amino acids are essential
• Amino acids are not produced by body so
must be consumed as foods
• Proteins make up muscle, bone, brain cells,
blood cells, genetic matter, skin, hair,
fingernails, etc.
• Proteins in food supply 4 Calories/g
SOURCES OF PROTEIN
• Complete proteins contain all essential
amino acids
– Found in fish, meat, poultry, eggs, milk,
cheese, yogurt
• Incomplete proteins lack some amino
acids
– Legumes, seeds, whole grains
LIPID FORMATION
• Formed when a fatty acid combines with a
glycerol molecule
• The hydroxyl group (–OH ) from one fatty
acid combines with the hydrogen (–H)
from the hydroxyl group (–OH) of the
glycerol molecule
• Water is released, making it a
condensation reaction
LIPID FORMATION
Glycerol + 3 Fatty Acids → Lipid (fat) + 3 water molecules
• Glycerol has alcohol group (–OH)
• Fatty acid has long carbon chain + COOH (acid)
LIPIDS or FATS
• Large, nonpolar,
biological molecules
• Contains C, H, O
• Make up structures of
cell membranes
(phospholipids)
• Fatty Acid is the
building block
• Triglyceride is fat
formed from three fatty
acids.
TYPES OF FATS
• Saturated fats, such as butter and lard, come
from animals
– Contain only single bonds
– Holds all hydrogen atoms (transfats)
• Unsaturated fats, called oils, come from plants
– Contains one or more double bonds
– Missing one or more pairs of hydrogen
– Healthier than saturated fats
FATS & HEALTH
• 30% Calories from fat
recommended
• 10% (maximum) from saturated fats
• Supply 9 Cal/g; most concentrated
form of energy
• Stored energy in the body
• Insulates, supports, and protects
vital body parts
• Protective barrier for skin
• Involved in hormone production
• 2/3 of the brain is fat!
ROLE OF FATS
• Add flavor to foods
• Carry vitamins A, D, E and K
• Cholesterol, found in foods of animal
origin, is needed to make and maintain cell
membranes
– HDL (high density lipoproteins) – “good”
cholesterol
– LDL (low density lipoproteins)- “bad”
cholesterol that clogs arteries
VITAMINS
• Regulators for body processes
• Do not supply energy
• Two Types
– Water-soluble vitamins pass easily into the
bloodstream; include Vitamin C and all B
vitamins
– Fat-soluble vitamins are stored in fatty issues;
Vitamins A, D, E, and K
MINERALS
• Inorganic substances that regulate body
processes
– For example, iron is essential for hemoglobin
• Hemoglobin carries oxygen in the blood
• Iron is available in foods, such as meat and fish
• Lack of iron can lead to anemia
– Calcium is necessary for bone strength and
development
• Lack of calcium leads to poor bone density and
possibly osteoporosis in later life
WATER
• Essential for body functions
• Body uses about 10 cups per day
• More water is necessary in high temperatures or
while exercising
• Role of water:
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Carries nutrients to the cell
Transports waste from the cell
Lubricates joints and membranes
Aids in swallowing and digesting foods
Perspiration
Absorbs nutrients
Absorbs wastes from body
Nutrients and Calorimetry
• Energy is released through chemical reactions
during metabolism.
• Different nutrients are used as fuel for
burning or as building material for the body.
1. Carbohydrates are nutrients burned as
fuel.
 1 gram carbohydrate = 4.0 Cal energy
2. Building nutrients include fats, proteins,
vitamins and minerals.
 1 gram fat = 9.0 Cal energy
 1 gram protein = 4.0 Cal energy
Nutrients and Calorimetry
• The energy unit for measuring energy in
foods is the nutritional or food Calorie
(Cal).
1 Cal = 1 kcal = 1000 cal
• Recall: The specific heat of water is
equal to
1.00 cal/g°C
Heat Equation with Foods
q = cm∆T
Variable
Representation
Unit
Heat Equation with Foods
q = cm∆T
Variable
Representation
Unit
q
The heat absorbed or released
cal
Heat Equation with Foods
q = cm∆T
Variable
Representation
Unit
q
The heat absorbed or released
cal
c
The specific heat
cal/g°C
Heat Equation with Foods
q = cm∆T
Variable
Representation
Unit
q
The heat absorbed or released
cal
c
The specific heat
cal/g°C
m
The mass of substance
g
Heat Equation with Foods
q = cm∆T
Variable
Representation
Unit
q
The heat absorbed or released
cal
c
The specific heat
cal/g°C
m
The mass of substance
g
∆T
The temperature change
°C
NUTRITION LABELS
RECALL
 1 gram carbohydrate provides 4 Cal of energy
 1 gram fat provides 9 Cal of energy
 1 g protein provides 4 Cal of energy
Nutrition labels give information about the grams of
carbohydrates, fats, and proteins in each serving.
FACTORS AFFECTING CALORIC NEED
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Activity level
Age
Gender
Metabolic rate
Rate of growth
• To lose weight safely, cut 500 calories per
day
THE END