Proteins. Building Blocks of Protein: Amino Acids All protein is composed of Amino Acids Amino Acids are Nitrogen bearing compounds that form the structural.
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Slide 1
Proteins
Slide 2
Building Blocks of Protein: Amino Acids All protein is composed
of Amino Acids Amino Acids are Nitrogen bearing compounds that form
the structural units of protein Amino means nitrogen containing
Proteins have carbon, hydrogen, oxygen, and 16% nitrogen Each Amino
Acid is joined by a peptide bond Two amino acids are called a
dipeptide Polypeptides are chains of up to 100 amino acids
Slide 3
Amino Acids When protein foods are eaten, proteins are broken
down into amino acids Amino acids are reassembled in the body to
form a variety of proteins The body requires 20 different amino
acids which are classified as: Indispensable Dispensable
Conditionally Indispensable
Slide 4
Classes of Amino Acids (Page 47 table 4-1) Indispensable Amino
Acids (Essential) Nine amino acids the body cannot manufacture in
sufficient quantity Vital to life and health Dispensable Amino
Acids (Non-Essential) Five amino acids that the body can synthesize
from other amino acids Conditionally Indispensable Amino Acids
(Non- Essential) Six amino acids that are normally synthesized in
the body by other amino acids Under stress and illness these amino
acids must be consumed in the diet
Slide 5
Functions of Protein Structural Tissue Building Protein Balance
Source of Energy Water and pH Balance Digestion Transportation
Hormones Blood Plasma (hemoglobin) Body Defense System
Slide 6
Tissue Building Fundamental structural material of every cell
Comprises bulk of: Muscles (actin, myosin, troponin, tropomyosin),
internal organs, brain, nerves, blood plasma (myoglobin,
hemoglobin), skin, hair, nails, hormones, and enzymes Protein
repairs worn-out, wasted, or damaged tissue (burns, cuts, and
scrapes; muscle tears after exercise)
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Protein Balance Nitrogen balance indicates how well the bodys
tissues are being maintained; it is achieved in healthy adults.
Protein balance Catabolism: Breakdown Anabolism: Resynthesis
(build-up) To maintain balance, nitrogen is converted to ammonia
and excreted as urea in urine (deamination)
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Protein Balance Nitrogen balance (intake = excretion) Positive
Nitrogen balance: body stores more than it excretes Pregnancy,
Infancy, Childhood, Adolescence Negative Nitrogen balance: body
takes in less than it excretes Illness and Malnutrition During a
period of negative nitrogen balance the person is not getting
enough protein in the diet and the body is breaking down tissue to
provide energy or other critical functions Kwashiorkor: Protein
deficiency disease
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Source of Energy Provides 4kcal/gram May provide body fuel if
the supply of carbohydrate and fat is insufficient for needs Less
efficient
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Water and pH Balance pH (potential of Hydrogen) is a measure of
the acidity or alkalinity of a solution The value of pH can be
between 0 and 14. The intermediate value is 7 (water); values lower
than 7 indicate acidic and values higher than 7 indicate alkaline
condition (soft drinks have a pH of 2.5) pH level of our bodies
should be between 7.2 and 7.6 (blood is between 7.35 and 7.45)
Proteins act as buffering agents (adjusts the pH of a solution) by
releasing or taking up excess acid within the body
Slide 12
Digestion, Transportation, and Hormones Enzymes are proteins
necessary for digestion Proteases are enzyme proteins Transport
agents Lipoproteins (HDLs and LDLs) Hemoglobin (oxygen carrier in
red blood cells) Protein Hormones Insulin and Glucagon
Slide 13
Body Defense System Proteins help build lymphocytes which are
white blood cells Defend the body against infection Antibodies also
called immunoglobulins which are large y- shaped proteins which
function to identify and help remove foreign antigens such as
viruses and bacteria
Slide 14
Food Sources of Protein Complete Proteins: All 9 indispensable
proteins in the quantity and correct ratio to maintain nitrogen
balance and allow for tissue growth and repair Primarily of animal
origin (egg, milk, meat, cheese, poultry, seafood) Soy products are
the only plant sources of complete protein Incomplete Proteins:
Deficient in one or more indispensable amino acids Grains, legumes,
nuts, seeds, fruits, vegetables
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Whey Protein It is the liquid that is left behind after the
first stages of cheese-making It looks like curdled milk The whey
is the liquid component that separates from the solid particles.
("Curds and whey" is, essentially, cottage cheese.) High in protein
and found in dairy products, protein shakes, bars, and many
processed foods Also known as whey protein isolates, whey protein
concentrate, whey protein hydolysate, and hydrolized protein
Slide 16
Is Whey Protein Good For You? Whey protein supplements are just
that, Supplements. They should never be used to replace protein
obtained from a healthy daily diet. Whey protein may cause allergic
reactions in people who suffer from lactose intolerance or who are
generally allergic to dairy products. Whey proteins may be easier
to digest
Slide 17
Soy Research suggests that daily intake of soy protein may
slightly lower levels of LDL cholesterol. However, the results have
been inconsistent. There is not enough scientific evidence to
determine whether soy supplements are effective for any other
health uses Soy is considered safe for most people when used as a
food Minor stomach and bowel problems such as nausea, bloating, and
constipation are possible Allergic reactions such as breathing
problems and rash can occur in rare cases
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Soy Soy's role in breast cancer is uncertain. Until more is
known about soy's effect on estrogen levels, women who have or who
are at increased risk of developing breast cancer or other hormone-
sensitive conditions (such as ovarian or uterine cancer) should be
careful about using soy and should discuss it with their
doctors
Slide 19
Vegetarian Diets Lacto-ovo vegetarian: Dairy products and eggs,
excluding meat and fish, to complement diet of plant foods
Lacto-vegetarian: Milk and milk products to complement diet of
plant foods Ovo-vegetarian: Eggs are only animal foods to
complement diet of plant foods Vegan: No animal foods, diet of
plant foods only
Slide 20
Health Benefits of Vegetarian Diets Lower levels of saturated
fat and cholesterol Lower rates of death from cardiovascular
disease (hypertension) Lower risk of type 2 diabetes and some forms
of cancer (colon and prostate) Lower risk of dementia Lower risk of
kidney disease Lower body mass index and prevalence of obesity
Higher levels of antioxidants
Slide 21
Vegetarian Diets Must combine foods to cover all amino acid
needs Grains and peas, beans, or lentils; legumes and seeds; grains
and dairy Brown rice and beans Whole grain bread with pea or lentil
soup Wheat or corn tortilla with beans Peanut butter on whole wheat
bread Falafel (chickpeas) on whole wheat pita bread Hummus on whole
wheat pita bread Whole wheat pasta tossed with peas, almonds, or
cheese Garden burger on a whole wheat bun
Slide 22
Vegetarian/Vegan Tips to Meet Protein Requirements Add beans,
seeds, or nuts to salads Eat pecans, almonds, walnuts, cashews and
peanut butter for protein Make smoothies with soy milk or hemp milk
Choose soy nuts over potato chips for a high-protein snack
Substitute quinoa for rice or pasta Sprinkle nuts and seeds on
cereal Crumple firm tofu into pasta sauces Add beans to soups Make
your own trail mix and include soynuts and almonds
Slide 23
Digestion of Proteins Mouth: Mastication (chewing) mixed with
saliva to form a bolus; a semisolid food mass Stomach: Chemical
digestion of protein begins in the stomach Hydrochloric acid
changes pepsinogen into pepsin Pepsin is the main gastric enzyme of
the stomach. It changes large amino acids into peptides
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Digestion of Proteins Small Intestine: Protein digestion is
completed here by enzymes from pancreas and intestine Pancreas:
Trypsin, Chymotrypsin, and Carboxypeptidase breaks up polypeptides
into dipeptides Intestines: Aminopeptidase and Dipeptidase breaks
up dipeptides into amino acids The free amino acids are ready to be
absorbed into blood circulation
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Body Needs for Protein Tissue growth Dietary protein quality
Chemical score (CS) Biologic value (BV) Net protein utilization
(NPU) Protein efficiency ratio (PER)
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Body Needs for Protein Tissue Growth: During rapid growth
periods, more protein per unit of body size is necessary to build
new tissue. Chemical score: Value derived from the amino acid
pattern of the food (an egg has a value of 100). Biologic value is
based on nitrogen balance Net protein utilization is based on
biologic value and the degree of digestibility. Protein efficiency
ratio is based on weight gain relative to protein intake Table 4-2
page 57 compares protein food scores
Slide 28
Dietary Deficiency or Excess Protein Energy Malnutrition (PEM)
Kwashiorkor: Acute deficiency of protein. Characteristics are edema
and bloated abdomen from lack of protein in blood to maintain fluid
balance (figure 4-6 page 57) Marasmus: Chronic deficiency of
protein (elderly and individuals with eating disorders) Excess
protein Usually also means excess fat intake Protein displaces
other healthy foods in diet Extra burden on kidneys
Slide 29
High Protein Diets Generally higher in total fat, saturated
fat, and cholesterol Initial weight loss is caused by ketosis and
fluid loss from a lack of carbohydrates Extra work for the kidneys
and liver to remove excess acids (deamination) Loss of muscle
tissue from a lack of carbohydrates Risk of deficiency
diseases
Slide 30
Dietary Guidelines? Recommended Dietary Allowances (RDAs)
Relate to age, sex, weight Highest at birth and slowly decline into
adulthood Men and women: 0.8 to 2.0 g/kg of desirable weight
Dietary Reference Intakes (DRIs) from National Academy of Sciences
10% to 35% of total caloric intake from protein (children and
adults)
Slide 31
Calculating Intake For Protein Calculate the protein needs of
an individual consuming 2800 kcal/day based on the recommendations
of 10% to 35% of total calories Calculate the protein needs of a
woman who is 5 feet six inches tall and weighs 150 pounds based on
the recommendations of.8 to 2.0 g/kg per day
Slide 32
Nutrition Assignment Refer to page 61 in your nutrition book
and answer Critical Thinking Questions 2 and 3