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Protein
Protein
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Surprisingly little is known about protein
and health but some recommendations
Adults need 0.8 grams of protein/kg of
body weight per day to keep from
slowly breaking down their own tissues
Just over 7 grams of protein are needed
for every 20 pounds of body weight
Protein
There's relatively little solid information
 on the ideal amount of protein in the
diet
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a healthy target for calories
contributed by protein
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the best kinds of protein.
Too Little Protein?
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the conditions known as
Kwashiorkor and Maramus.
growth failure
loss of muscle mass
decreased immunity
weakening of the heart and
respiratory system
You die
Too Much Protein?
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Digesting it releases acids that the body
usually neutralizes with calcium and
other buffering agents in the blood.
Eating lots of protein, such as the
amounts recommended in the so-called
low-carb or no-carb diets, removes lots
of calcium from the body.
Some of this may be pulled from bone.
What is Protein?
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Take away the water and about 75 percent of
body weight is protein
Muscle, bone, skin, hair, and virtually every
other body part or tissue. (25% of muscle)
Enzymes that power many chemical reactions
and the hemoglobin that carries oxygen
At least 10,000 different proteins make
the body what it is.
What is Protein?
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Twenty or so basic building blocks, called
amino acids, provide the raw material for all
proteins. Following genetic instructions, the
body strings together amino acids.
Some genes call for short chains, others are
blueprints for long chains that fold, origamilike, into intricate, three-dimensional
structures.
What is Protein?
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Because the body doesn't store amino
acids, as it does fats or carbohydrates, it needs
a daily supply of amino acids to make new
protein.
It does not need a supply of dietary amino
acids to make ALL the protein the body
synthesizes in a day
Protein the body no longer requires is
broken down to its component amino
acids and they may be used to synthesis
another body protein
Amino Acids
Side group
H
H
O
N C C
Amine
Group
H
OH
Acid
Group
Side group
differences
is how the twenty
amino acids are
different .
The Chemist’s View of Proteins
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Amino Acids
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The unique side groups result in
differences in the size, shape and electrical
charge of an amino acid
The Chemist’s View of Proteins
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Amino Acids
 Nonessential amino acids, also called
dispensable amino acids, are ones the
body can create.
The Chemist’s View of Proteins
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Amino Acids
 Essential amino acids, also called
indispensable amino acids, must be
supplied by the foods people consume.
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Essential amino acids include histidine,
isoleucine, leucine, lysine, methionine,
phenyalanine, threonine, tryptophan, and
valine.
Conditionally essential amino acids refer to
amino acids that are normally nonessential
but essential under certain conditions.
The Chemist’s View of Proteins
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Proteins
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Amino acid chains are linked by peptide
bonds in condensation reactions.
 Dipeptides have two amino acids
bonded together.
 Tripeptides have three amino acids
bonded together.
 Polypeptides have more than two
amino acids bonded together.
Peptide Bonding
H
H
O
H
H
N C C
OH H
Side group 1
Amino Acid 1
water
O
H
N C C
OH
Side group 2
Amino Acid 2
Amino Acid Sequence
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Protein is made by bonding amino
acids in a specific sequence
.
Each amino acid must be but in the
order specified by the genetic code
responsible for synthesizing the protein
If an (essential) amino acid is
unavailable, protein synthesis is
limited
Amino Acid Sequence
Amino acid 1
Amino acid 2
Amino Acid Sequence
Amino acid3 3
Amino acid 1
Amino acid 2
Amino Acid Sequence
Amino acid 3
Amino acid 1
Amino acid 2
Amino acid 4
Amino Acid Sequence
Amino acid3 3
Amino acid 1
Amino acid 2
Amino acid 4
Amino acid 5
Amino acid 7
Amino acid 9
Amino acid 8
Amino acid 6
Amino acid 10
Amino acid 11
Amino acid 12
Amino acid 13
ETC>
Proteins in the Body
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Protein Synthesis
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Synthesis is unique for each human being
and is determined by the amino acid
sequence.
Delivering the instructions through
messenger RNA (genetic material)
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Carries a code to the nuclear membrane
Presents a list to make a strand of protein
Transfer RNA lines up the amino acids and
brings them to the messenger
Proteins in the Body
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Proteins are versatile and unique. The
synthesis of protein is determined by
genetic information.
Protein is constantly being broken down
and synthesized in the body.
Researchers measure nitrogen balance
to study synthesis, degradation and
excretion of protein.
Proteins in the Body
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Protein has many important functions in
the body.
Protein can be used for energy if needed;
(gluconeogenesis) and its excesses are
stored as FAT.
The study of proteins is called proteomics.
Proteins in the Body
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Roles of Proteins
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Building Materials for Growth and
Maintenance = LIFE
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A matrix of collagen is filled with minerals to
provide strength to bones and teeth.
Replaces tissues including the skin, hair, nails,
and GI tract lining
Proteins in the Body
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Roles of Proteins
 Enzymes are proteins that facilitate
anabolic (building up) and catabolic
(breaking down) chemical reactions.
Proteins in the Body
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Roles of Proteins
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Hormones regulate body processes
and some hormones are proteins.
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An example is insulin.
Proteins in the Body
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Roles of Proteins
 Regulators of Fluid Balance
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Plasma proteins attract water
Maintain the volume of body fluids to prevent
edema which is excessive fluid
Maintain the composition of body fluids
Proteins in the Body
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Roles of Proteins
 Acid-Base Regulators
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Act as buffers by keeping solutions acidic or alkaline
Acids are compounds that release hydrogen ions in a
solution.
Bases are compounds that accept hydrogen ions in a
solution.
Acidosis is high levels of acid in the blood and body
fluids.
Alkalosis is high levels of alkalinity in the blood and body
fluids.
Proteins in the Body
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Roles of Proteins
 Transporters
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Carry lipids, vitamins, minerals and oxygen in
the body
Act as pumps in cell membranes, transferring
compounds from one side of the cell membrane
to the other
Proteins in the Body
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Roles of Proteins
 Antibodies
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are large proteins that are found in blood or other
bodily fluids of vertebrates
 Fight bacteria and viruses, also known as
antigens, that invade the body
 Provide immunity to fight an antigen more
quickly the second time exposure occurs
Proteins in the Body
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Roles of Proteins
 Source of energy and
glucose if needed
 Other Roles
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Blood clotting by
producing fibrin which
forms a solid clot
Vision by creating lightsensitive pigments in the
retina
Proteins in the Body
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A Preview of Protein Metabolism
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Protein Turnover and the Amino Acid Pool
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Protein turnover is the continual making and
breaking down of protein.
Amino acid pool is the supply of amino acids
that are available.
Amino acids from food are called
exogenous.
Amino acids from within the body are
called endogenous.
Amino Acid Pool
Cellular
Proteins
Dietary
Proteins
Amino Acids
Amino Acid
Pool
Cellular
Proteins
ENERGY
NH3
Proteins in the Body
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A Preview of Protein Metabolism
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Nitrogen Balance
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Zero nitrogen balance is nitrogen equilibrium,
when input equals output.
Positive nitrogen balance means nitrogen
consumed is greater than nitrogen excreted.
Negative nitrogen balance means nitrogen
excreted is greater than nitrogen consumed.
Proteins in the Body
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A Preview of Protein Metabolism
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Using Amino Acids to Make Proteins or
Nonessential Amino Acids – Cells can assemble
amino acids into the protein needed.
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Using Amino Acids to Make Other
Compounds
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Neurotransmitters are made from the amino acid
tyrosine.
Tyrosine can be made into the melanin pigment or
thyroxine.
Tryptophan makes niacin and serotonin.
Proteins in the Body
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A Preview of Protein Metabolism
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Dietary
Protein
Using Amino Acids for Energy and Glucose
 There is no readily available storage form of
protein.
 Breaks down tissue protein for
energy if needed
glucose
Amino Acids
Body
Protein
Proteins in the Body
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Proteins are versatile and unique. The synthesis
of protein is determined by genetic information.
Protein is constantly being broken down and
synthesized in the body.
Researchers measure nitrogen balance to study
synthesis, degradation and excretion of protein.
Protein has many important functions in the
body.
Protein can be used for energy if needed; its
excesses are stored as fat.
The study of proteins is called proteomics.
Proteins in the Body
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A Preview of Protein Metabolism
 Deaminating Amino Acids
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Nitrogen-containing amino groups are removed.
Ammonia is released into the bloodstream.
Ammonia is converted into urea by the liver.
Kidneys filter urea out of the blood.
Using Amino Acids to Make Fat
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Excess protein is deaminated and converted into fat.
Nitrogen is excreted.
Proteins in the Body
A Preview of Protein Metabolism
Deaminating Amino Acids
H
H
H
O
N C C
•Nitrogen-containing amino
groups are removed.
•Ammonia is released into
the bloodstream.
OH •Ammonia is converted into
Side group
urea by the liver.
•Kidneys filter urea out of
the blood.
Proteins in the Body
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A Preview of Protein Metabolism
Using Amino Acids to Make Fat
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Dietary
Protein
Excess protein is deaminated and converted
into fat.
Nitrogen is excreted.
FAT
Body
Protein
Amino Acids
Ammonia
Dietary Protein
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Complete protein contains all the
essential amino acids needed to build
new proteins.
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Animal sources of protein tend to
be complete
Incomplete proteins sources lack
one or more essential amino acids that
the body can't make from scratch or
create by modifying another amino acid
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These usually come from fruits,
vegetables, grains, and nuts.
Protein in Foods
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Eating foods of high-quality protein is the best
assurance to get all the essential amino acids.
Complementary proteins can also supply all the
essential amino acids.
A diet inadequate in any of the essential amino
acids limits protein synthesis.
The quality of protein is measured by its amino
acid content, digestibility, and ability to support
growth.
Protein in Foods
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Protein Quality
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Digestibility
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Depends on protein’s food source
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Animal proteins are 90-99% absorbed.
Plant proteins are 70-90% absorbed.
Soy and legumes are 90% absorbed.
Other foods consumed at the same
time can change the digestibility
Protein in Foods
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Protein Quality
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Amino Acid Composition
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The liver can produce nonessential amino acids.
Cells must dismantle to produce essential amino acids if
they are not provided in the diet.
Limiting amino acids are those essential amino acids that
are supplied in less than the amount needed to support
protein synthesis.
Reference Protein is the standard by which
other proteins are measured. (Egg White)
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Based on their needs for growth and development,
preschool children are used to establish this standard.
Protein in Foods
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Protein Quality
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High-Quality Proteins
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Contains all the essential amino acids
Animal foods contain all the essential amino
acids.
Plant foods are diverse in content and tend to
be missing one or more essential amino acids.
Complementary Proteins
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Combining plant foods that together contain all
the essential amino acids
Used by vegetarians
Protein in Foods
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Protein Quality
 A Measure of Protein Quality - PDCAAS
(protein digestibility-corrected amino acid
score)
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Compares amino acid composition of a protein
to human amino acid requirements
Adjusts for digestibility
Protein in Foods
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Protein Regulation for
Food Labels
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List protein quantity in
grams
% Daily Values is not
required but reflects
quantity and quality of
protein using PDCAAS.
Health Effects and Recommended Intakes
of Protein
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Protein deficiency and excesses can be
harmful to health.
Protein deficiencies arise from proteindeficient diets and energy-deficient diets.
This is a worldwide malnutrition
problem, especially for young children.
High-protein diets have been implicated
in several chronic diseases.
Health Effects and Recommended Intakes
of Protein
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Protein-Energy Malnutrition (PEM) –
also called protein-kcalorie malnutrition
(PCM)
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Classifying PEM
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Chronic PEM and acute PEM
Maramus, kwashiorkor, or a combination of the
two
Health Effects and Recommended Intakes
of Protein
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PEM
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Marasmus
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Infancy, 6 to 18 months of age
Severe deprivation or impaired
absorption of protein, energy,
vitamins and minerals
Develops slowly
Severe weight loss and muscle wasting,
including the heart
< 60% weight-for-age
Anxiety and apathy
Good appetite is possible
Hair and skin problems
Marasmus
Health Effects and Recommended Intakes
of Protein
PEM
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Kwashiorkor
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Older infants and young children, 18
months to 2 years of age
Inadequate protein intake, infections
Rapid onset
Some muscle wasting, some fat
retention
Growth is 60-80% weight-for-age
Edema and fatty liver
Apathy, misery, irritability and sadness
Loss of appetite
Hair and skin problems
Kwashiorkor
d
Health Effects and Recommended Intakes
of Protein
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PEM
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Marasmus-Kwashiorkor Mix
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Both malnutrition and infections
Edema of kwashiorkor
Wasting of marasmus
Health Effects and Recommended Intakes
of Protein
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PEM
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Infections
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Lack of antibodies to fight infections
Fever
Fluid imbalances and dysentery
Anemia
Heart failure and possible death
Rehabilitation
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Nutrition intervention must be cautious, slowly
increasing protein.
Programs involving local people work better.
Health Effects and Recommended Intakes
of Protein
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Health Effects of Protein
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Heart Disease
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Foods high in animal protein also tend to
be high in saturated fat.
Homocysteine levels increase cardiac
risks.
Arginine may protect against cardiac risks.
Health Effects and Recommended Intakes
of Protein
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Health Effects of Protein
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Cancer
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A high intake of animal protein is associated
with some cancers.
Is the problem high protein intake or high fat
intake?
Health Effects and Recommended Intakes
of Protein
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Health Effects of Protein
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Adult Bone Loss (Osteoporosis)
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High protein intake associated with increased
calcium excretion.
Inadequate protein intake affects bone health
also.
Health Effects and Recommended Intakes
of Protein
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Health Effects of Protein
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Weight Control
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High-protein foods are often high-fat foods.
Protein at each meal provides satiety.
Adequate protein, moderate fat and sufficient
carbohydrate better support weight loss.
Kidney Disease
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High protein intake increases the work of the kidneys.
Does not seem to cause kidney disease
Health Effects and Recommended Intakes
of Protein
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Recommended Intakes of Protein
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10-35% energy intake
Protein RDA
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0.8 g/kg/day
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Assumptions
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People are healthy.
Protein is mixed quality.
The body will use protein efficiently.
Health Effects and Recommended Intakes
of Protein
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Recommended Intakes of Protein
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Adequate Energy
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Must consider energy intake
Must consider total grams of protein
Protein in abundance is common in the
U.S. and Canada.
Health Effects and Recommended Intakes
of Protein
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Protein and Amino Acid
Supplements
 Protein Powders have not been
found to improve athletic
performance.
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Whey protein is a waste product of
cheese manufacturing. (Chicken Wings
of the supplement industry)
Purified protein preparations increase
the work of the kidneys.
Health Effects and Recommended Intakes
of Protein
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Protein and Amino Acid Supplements
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Amino Acid Supplements are not beneficial and
can be harmful.
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Branched-chain amino acids provide little fuel and
can be toxic to the brain.
Lysine appears safe in certain doses.
Tryptophan has been used experimentally for sleep
and pain, but may result in a rare blood disorder.
Protein & Chronic Disease
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Cardiovascular disease; it is possible that
eating more protein, especially vegetable
protein, while cutting back on easily digested
carbohydrates may benefit heart disease
Diabetes; the amount of protein in the diet
doesn't seem to adversely affect the
development of type 2 (adult-onset) diabetes,
although research in this area is ongoing
Cancer; there's no good evidence that
eating a little protein or a lot of it influences
cancer risk
Protein & Weight Control
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High-protein, low-carbohydrate diets may
work more quickly than low-fat diets, at least
in the first six months.
After a year or so, weight loss is about equal
Protein & Weight Control
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Slower stomach emptying means you feel
full for longer and get hungrier later.
Protein's gentle, steady effect on blood
sugar avoids the quick, steep rise in blood
sugar that occurs after eating a rapidly
digested carbohydrate, like white bread or
baked potato
The body uses more energy to digest
protein than it does to digest fat or
carbohydrate.
Recommendations for
Protein Intake
 Get a good mix of proteins. Almost any
reasonable diet will give enough protein.
Eating a variety of foods will ensure that all of
the amino acids need are available.
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Pay attention to the protein package
Some comes packaged with lots of unhealthy
fat, Some without much saturated fat and
with plenty of healthful fiber and
micronutrients.
Recommendations for
Protein Intake
Balance carbohydrates and protein.
 Cutting back on highly processed
carbohydrates and increasing protein
improves levels of blood triglycerides and
HDL, and may reduce the chances of having
a heart attack, stroke, or other form of
cardiovascular disease.
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It may also make you feel full longer, and
stave off hunger pangs.
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Too much protein, though, could weaken
bones.
Recommendations for
Protein Intake
AGE
0-6 months
 6-12 mo
 1-3 years
 4-6
 7-14
 15-18
 Adults
grams/pound
1 gram/#
.7 gms/#
.6 gms/#
.55 gms/#
.45 gms/#
.4 gms/#
.35 gms/#
amount
13 grams
14 grams
16 grams
24 grams
28-45 gms
44-59 gms
50-65 gms
Protein Intake Summary
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Important for growth (height) and development
Needed in smaller amount than most people
think (.8 grams/kilogram BW) = RDA
Can be gotten from a variety of plant foods as
well as the animal foods (meat, dairy)
Use as a part of the meal, not as the meal (eat
lean, less and last)