DNT 200 NUTRITION FOR HEALTH SCIENCES

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DNT 200NUTRITION FOR HEALTH SCIENCES

• PROTEIN

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PROTEIN

• When mighty roast beef was the Englishmans food,
• It ennobled our hearts and enriched our blood,
• Our soldiers were brave and our courtiers were
  good.
• Oh! the roast beef of old England!
• Richard Leveridge
• (1670-1758)
• English singer and composer

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PROTEIN

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PROTEIN

• DEFINITION
• Proteins are compounds composed of carbon,
  hydrogen, oxygen, and nitrogen atoms arranged
  into amino acids linked in a chain. Some amino
  acids also contain sulfur atoms

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PROTEIN

• AMINO ACIDS
• Amino Acids are compounds that serve as the
  building blocks of proteins each contains an
  amino group, an acid group, a hydrogen atom, and
  a distinctive side group attached to a central
  carbon atom
• Nine essential amino acids
• Thirteen non-essential amino acids
• Some are able to be manufactured by chemists

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PROTEIN

• AMINO ACIDS

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids -- Amino Acids that the
  body cannot synthesize in amounts sufficient to
  meet physiological need

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Valine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Leucine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Isoleucine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Threonine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Lysine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Sulfur Containing Amino Acids
• (Grouped together because if the body has enough
  Methionine, it can change it into Cysteine)
• Methionine Cysteine
  (non-essential)

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Aromatic Amino Acids (contain benzene ring)
• (Grouped together because if the body has enough
  Phenylalanine, it can change it into Tyrosine)
• Phenylalanine Tyrosine (non-essential)

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Tryptophan

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Histidine

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PROTEIN

• AMINO ACIDS
• Essential Amino Acids
• Need to be obtained from foods
• Sometimes a non essential amino acid can be come
  essential -- Examples
• Illness can demand requirements beyond the bodys
  ability to produce the amino acid
• In Phenylketonuria (PKU) the body is unable to
  convert phenylalanine to tyrosine, therefore
  tyrosine becomes essential

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PROTEIN

• AMINO ACIDS
• Non-essential Amino Acids -- Amino Acids that the
  body is able to manufacture

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PROTEIN

• AMINO ACIDS
• Non-essential Amino Acids
• Alanine
• Arginine
• Asparagine
• Aspartic Acid
• Cystine
• Glutamic Acid
• Glutamine
• Glycine
• Proline
• Serine
• Tyrosine

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PROTEIN

• SURFACE STRUCTURE
• Have a great variety of surface structures
  (shapes) to perform distinct, individual, and
  specialized functions

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PROTEIN

• SURFACE STRUCTURE

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PROTEIN

• SURFACE STRUCTURE
• Human insulin is identical to pig insulin, except
  that the last amino acid of the B-chain for the
  pig is alanine (Ala) instead of threonine (Thr)

Ala
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PROTEIN

• The average amino acid weighs 6.25 times as much
  as the nitrogen it contains, therefore
• Nitrogen represents 16 of the weight of the
  protein

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PROTEIN

• DIGESTION AND ABSORPTION
• Role of protein is not to provide the body with
  proteins, but to supply amino acids from which
  the body can make protein

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PROTEIN
HCl

• DIGESTION AND ABSORPTION
• Hydrolysis of proteins begins in the stomach
• HCl uncoils (denatures) the proteins tangled
  strand so that digestive enzymes can attack the
  peptide bonds

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PROTEIN

• DIGESTION AND ABSORPTION
• Pepsin (a gastric protease) cleaves proteins --
  large polypeptides are broken down into smaller
  polypeptides
• When these polypeptides enter the small intestine
  pancreatic and intestinal proteases hydrolyze
  them further into short peptide chains
  (oligopeptides) tripeptides, dipeptides, and
  amino acids

Pepsin
Proteases
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PROTEIN

• DIGESTION AND ABSORPTION
• Peptidase enzymes on the surface of the
  intestinal cells break more of the peptide bonds
• A mixture of free amino acids, dipeptides, and
  tripeptides is left
• Distinct carriers then transport these pieces
  across the intestinal cells for passage into the
  blood

Absorption
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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Enzymes
• Enzymes are proteins that facilitate chemical
  reactions without being changed in the process
• Are essential to all life processes
• Are protein catalysts

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Enzymes (continued)
• Act upon other proteins
• You eat protein
• Digestive enzymes (proteins) break down protein
  into amino acids
• Amino acids enter the cells where proteins
  (enzymes) put them together into long chains
  whose sequence is specified by genes
• Chains fold and twist themselves to form
  proteins some of these proteins become enzymes
  themselves
• These enzymes may then be used to break apart or
  put together other compounds

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Fluid Balance
• Fluids are present in several body compartments
• Spaces inside blood vessels
• Spaces within the cells (outside the blood
  vessels)

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Fluid Balance (continued)
• Fluids go back and forth in these spaces and
  proteins (together with minerals) help to
  maintain the needed distribution of these fluids

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Fluid Balance (continued)
• Proteins are large
• Proteins are attracted to water (hydrophilic)
• Being large, proteins cannot pass freely across
  cell membranes that separate body compartments
• Attracting water makes proteins even larger
• A cell wants to keep a certain amount of water in
  its interior space but cant manufacture the
  water directly
• The cell can manufacture protein and these
  proteins will hold water
• Therefore, the cell uses proteins to regulate the
  distribution indirectly

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Acid-Base Balance
• Acids are compounds that release hydrogen ions in
  solution
• Bases are compounds that accept hydrogen ions in
  a solution
• Acid-Base Balance is the equilibrium in the body
  between acid and base concentrations

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Acid-Base Balance (continued)
• Normal body processes continually produce acids
  and bases, which must be carried by the blood to
  the organs of excretion
• Blood must do this without allowing its own
  acid-base balance to be affected
• Proteins act as buffers, picking up hydrogens
  (acid) when there are too many and releasing them
  when there are too few

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Acid-Base Balance (continued)
• Acidosis
• Results when the blood pH limit falls below 7.35
  and causes proteins to undergo denaturation --
  they loose their shape and ability to function
• Disturbing a proteins shape renders it useless
  e.g. hemoglobin looses its capacity to carry
  oxygen (if unchecked, can be fatal)
• Alkalosis
• Results when the blood pH limit rises above 7.45
• Can cause coma or death

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Acid-Base Balance (continued)

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Acid-Base Balance (continued)
• By accepting and releasing hydrogen ions,
  proteins act as buffers maintaining acid-base
  balance of the blood and body fluids

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Antibodies
• Antibodies are large proteins of the blood and
  body fluids, produced by the immune system in
  response to the invasion of the body by foreign
  molecules (usually proteins called antigens)

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Antibodies (continued)
• Combine with and inactivate the foreign invaders,
  thus protecting the body
• Act against viruses, bacteria, and other disease
  agents
• Without adequate protein, the body cannot
  maintain its resistance to disease (immunity)

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Hormones
• Hormones are messenger molecules
• Are secreted by a variety of endocrine glands in
  response to altered conditions in the body
• Each travels to one or more specific target
  tissues or organs where is elicits a specific
  response

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Hormones (continued)
• Some are made up of amino acids (others are
  sterols such as testosterone)
• Examples
• Insulin and glucagon help regulate the blood
  glucose
• The thyroid hormone helps regulate the bodys
  basal metabolic rate

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Transport Proteins
• Some act as pumps picking up compounds on one
  side of cell membranes and depositing them on the
  other side
• Others move about in body fluids carrying
  nutrients and other molecules from one organ to
  another

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Transport Proteins (continued)
• Examples
• Hemoglobin -- carries oxygen from the lungs to
  the bodys cells
• Lipoproteins transport lipids around the body

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Blood Clotting
• Fibrin, a stringy insoluble mass of protein
  fibers, facilitates blood clotting

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Visual Pigments
• Opsin, the protein portion of the visual pigment
  molecule in the cells of the retina, responds to
  light by changing its shape thus initiating the
  nerve impulses that convey the sense of light to
  higher brain centers

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PROTEIN

• PROTEINS IN THE BODY
• Functions
• Structural Proteins
• Collagen
• Is the main fibrous protein (others are elastin
  and keratin)
• Helps make scar tissue, forms the matrix of bones
  and teeth
• Forms the material of ligaments and tendons

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PROTEIN

• PROTEINS IN THE BODY
• Pressure Sores
• Also known as decubitus ulcers, bed sores
• Caused by
• Unrelieved pressure on the skin and underlying
  tissues
• Friction (being pulled across bed sheets)
• Shear (sliding down in a bed or chair causing the
  skin to fold over itself and cutting off blood
  supply)
• Poor nutrition, especially protein, may lead to
  skin breakdown
• Four stages

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PROTEIN

• PROTEINS IN THE BODY
• Pressure Sores
• Stage 1
• Redness and heat over a pressure point

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PROTEIN

• PROTEINS IN THE BODY
• Pressure Sores
• Stage 2
• Destruction of the epidermis and partial
  destruction of the dermis

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PROTEIN

• PROTEINS IN THE BODY
• Pressure Sores
• Stage 3
• All the layers of the skin are destroyed and a
  deep crater forms

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PROTEIN

• PROTEINS IN THE BODY
• Pressure Sores
• Stage 4
• Ulcer extends through the skin and subcutaneous
  tissues and may involve bone, muscle, and other
  structures.
• Patient experiences fluid loss, pain, and is at
  great risk for infection.

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PROTEIN

• PROTEINS IN FOODS
• Role is not to supply the body protein directly
  but to supply amino acids from which the body can
  make its own protein
• Protein Quality
• Complete Protein is a protein that contains all
  the amino acids essential in human nutrition in
  amounts adequate for human use
• Must contain the nine essential amino acids and
  enough nitrogen and energy for the synthesis of
  the other thirteen

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PROTEIN

• PROTEINS IN FOODS
• Protein Quality (continued)
• Body makes only complete proteins
• Body uses amino acids in a specific ratio to one
  another
• If one amino acid is supplied in an amount
  smaller than needed, synthesis will be limited
• Concept of the limiting amino acid
• A chain is only as strong as its weakest link
• The limiting amino acids are the sulfur
  containing ones (methionine and cysteine),
  tryptophan, and lysine-- these are a little
  harder to get than the others
• Dietary protein will not be used efficiently when
  energy from carbohydrate and fat is lacking
  (protein sparing effect of carbohydrate and fat)

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PROTEIN

• PROTEINS IN FOODS
• Protein Quality (continued)
• Generally, proteins from animals is complete
  protein (exception is gelatin)
• Plant protein is variable
• Corn protein is incomplete
• Soy protein is complete

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PROTEIN

• PROTEINS IN FOODS
• Protein Quality (continued)
• Complementary Protein -- two or more proteins
  whose amino acid assortments complement each
  other in such a way such that the essential amino
  acids missing from one are supplied by the other
• The educated vegetarian can choose a diet that is
  adequate in protein by choosing a variety of
  legumes, grains, and vegetables

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PROTEIN

• PROTEINS IN FOODS
• Protein Quality (continued)
• Digestibility
• Digestibility is a measure of the amount of amino
  acids absorbed from a given protein intake
• High quality protein is an easily digestible
  complete protein
• Reference Protein
• Egg protein
• Used by the Food and Agriculture Organization
  (FAO) and World Health Organization (WHO) as a
  standard against which to measure the quality of
  other proteins

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PROTEIN

• PROTEINS IN FOODS
• SOURCES
• Milk -- 8 grams per cup
• Meat -- 7 grams per ounce
• Vegetables -- 2 grams per 1/2 cup
• Starch/bread -- 3 grams per serving
• Fruits -- negligible
• Fats -- negligible

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PROTEIN

• PROTEINS IN FOODS
• SOURCES

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Protein Energy Malnutrition is a deficiency of
  both protein and energy
• Kwashiorkor -- a form of PEM that results either
  from inadequate protein intake or, more commonly,
  from infections
• Is the Ghanaian name for the evil sprit that
  infects the first child when the second child is
  born
• Theory -- May be a form of food poisoning
  superimposed on malnutrition

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Kwashiorkor (continued)
• Symptoms
• Growth slows
• Hair looses color
• Skin becomes patchy and scaly (sometimes with
  ulcers and sores that fail to heal)
• Limbs and face become swollen with edema (protein
  in the blood becomes depleted and water cannot be
  held there, instead it seeps into interstitial
  space and accumulates)
• Belly bulges with fatty liver
• Sickens easily, becomes weak, fretful, and
  apathetic

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Kwashiorkor (continued)
• Occurs on every continent
• Typically sets in at the age of two

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Kwashiorkor (continued)

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Kwashiorkor (continued)

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Marasmus -- the disease of starvation
• Occurs in persons who receive little of no food
• Marasmic child looks like skin and bones
• Often sick because resistance to disease is low
• Muscles are wasted, including the heart
• Little or no fat to insulate against the cold
• Occurs most commonly in children 6-18 months old
• Impairs brain development
• Brain normally grows to adult size by 2 years of
  life
• May have permanent effect on learning ability

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Marasmus

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Energy Malnutrition (PEM)
• Marasmus

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Bodys Priority System (Protein Priority System)
• 1. Abandons less vital systems first (hair and
  pigments which are made of amino acids) are the
  first to go
• 2. Antibodies are degraded so their amino acids
  can be used as building blocks for the heart,
  lungs, and brain tissues
• 3. Resistance to infection is therefore lowered
• 4. Malnutrition and infection are a deadly
  combination

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PROTEIN

• HEALTH EFFECTS OF PROTEIN
• Protein Excess
• No Benefits
• Excess NH2 must be excreted causing kidneys to
  work harder
• Excess amino acids are stored as fat
• Risks
• Obesity -- protein-rich foods are often high fat
  foods
• The more protein consumed, the more likely fruits
  and vegetables will be crowded out of the diet,
  making in inadequate in other nutrients
• Studies suggest diets high in protein promote
  calcium excretion

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PROTEIN

• RECOMMENDED PROTEIN INTAKES
• Body Losses
• Skin cells flake off or are rubbed off every day
• Hair and nails grow longer and are shed or cut
  away
• People need to replace losses
• If the body is growing, the needs are greater
  than just for maintenance

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PROTEIN

• RECOMMENDED PROTEIN INTAKES
• Nitrogen Balance -- the amount of nitrogen
  consumed (N in) as compared with the amount of
  nitrogen excreted (N out)
• If the body maintains in its tissues the same
  amount of protein from day to day it is in
  nitrogen balance
• If the body looses protein it is in negative
  nitrogen balance
• Fasting
• Starvation
• Illness
• Burn victims (forced to use protein for energy)

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PROTEIN

• RECOMMENDED PROTEIN INTAKES
• If the body gains protein it is in positive
  nitrogen balance
• Growing children
• Pregnant women

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PROTEIN

• RECOMMENDED PROTEIN INTAKES
• DIETARY REFERENCE INTAKE VALUE
• AI
• Males over 18 -- 56 grams
• Females over 18 -- 46 grams
• RDA
• Healthy adults over 18 need 0.8 grams of high
  quality protein per kilogram of appropriate or
  average body weight for height
• 2002 Data

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PROTEIN

• RECOMMENDED PROTEIN INTAKES
• Assumptions
• Protein eaten will be of high quality
• It will be consumed with adequate energy from
  carbohydrate and fat
• Other nutrients in the diet will be adequate
• Individual is healthy and there is no unusual
  metabolic need for protein