Transcript Document

Chapter 6
Proteins
Patty Maloney MSN/Ed
1
Proteins
• Proteins-organic compounds formed by linking
many smaller molecules of amino acids.
• Amino acids-organic compounds made of carbon,
hydrogen, and oxygen.
• Protein in food is our only source of amino acids,
which are necessary
for every aspect of human

Inc.anafflaefEleve
life.
Inc.Alleeved.
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Amino Acids: Building Blocks
• Each protein is composed of hundreds of 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
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Functions of Proteins
• Growth & Maintenance ; replacement of cells.
• Creation of Communicators and Catalysts;
hormones, blood clotting.
• Immune System Response; defense system.
• Fluid & Electrolyte Regulation
• Acid-Base Balance.
• Transportation of Nutrients

Inc.anafflaefEleve
Inc.Alleeved.
4
Protein Foods
• The protein in foods are categorized by the
essential amino acids they contain.
• Complete protein-contains all nine essential
amino acids to support growth and maintenance.
• Sources-animal-derived foods, including meat,
poultry, fish, eggs,
and dairy products.

Inc.anafflaefEleve
Inc.Alleeved.
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Protein
• Incomplete Proteins-lack one or more of the nine
essential amino acids.
• Does not supply sufficient amount of amino acids
to support life.
• Plant foods are incomplete sources, grains and
legumes are better
sources.

Inc.anafflaefEleve
Inc.Alleeved.
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Classes of Amino Acids
• Essential amino acids – 9 (lycine)
• Body cannot manufacture, must come from diet
• Conditionally essential amino acids – 5 (cysteine)
• Body can synthesize from indispensable, do not have to come
from diet (may be lacking in disease process).
• Nonessential amino acids – 6 (alanine)
• Normally synthesized but some health conditions may require
dietary intake (Table 5-2).
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A Healthy Balance
• Protein balance
• Catabolism: breakdown of proteins
• Anabolism: resynthesis of proteins
• Nitrogen balance (intake = excretion)
• Nitrogen equilibrium (ideal)
• Positive nitrogen balance: body stores more protein than
it excretes (ie, growth, preg, lact)
• Negative nitrogen balance: body takes in less protein
than it excretes (ie, malnutrition, illness)
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Food Source of Proteins

Food Sources of Protein
• Complete proteins – contain all 9 essential amino
acids
• Meat, fish, eggs, seafood (animal)
• Soy (plant)
• Incomplete proteins (lack one or more essential
amino acids).
• Plant-origin foods
•
•
•
•
Grains
Legumes (peas, beans, peanuts, lentils)
Nuts
Seeds
1
Vegetarian Diets
• Approx. 3-5% of population
• Reasons = religious beliefs (buddhism, hinduism,
7th day Adventist), animal cruelty concerns,
environmental concerns, aversion to animal
products
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Vegetarian Categories
• Vegan-includes all plant foods, grains, legumes,
fruits, vegetables, seeds and nuts. Excludes all
animal-derived foods.
• Lacto-vegetarian-includes all plant foods plus
dairy products, (milk, cheese, yogurt, and butter).
Excludes animal meat, (meat, fowl, fish, and
eggs).

Inc.anafflaefEleve
Inc.Alleeved.
1
Vegetarian Diets
• Ovo-lacto vegetarian-includes all plant foods,
dairy products, and eggs. Excludes animal meat.
• Pescetarian-includes all plant foods, dairy
products, eggs and fish. Excludes meat and fowl.
• Flexitarian-includes all plant foods, dairy, and
eggs, with occasional consumption of meat, fowl,
or fish. No exclusions, but minimal consumption
of animal meat.

Inc.anafflaefEleve
Inc.Alleeved.
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Digestion of Proteins
• Mouth – mechanical digestion, chewing
• Stomach: enzymes to breakdown protein
into amino acids
• Pepsin **
• Hydrochloric acid
• Small intestine
• Pancreatic secretions aid digestion
• Trypsin, chymotrypsin, carboxypeptidase
• Intestinal secretions
• Aminopeptidase, dipeptidase
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Summary of Protein Digestion
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Body Needs for Protein
• Tissue growth
* more protein needed during growth periods
* fetus, infant, children, adolescents
• Additional needs caused by illness
* More protein needed during illness (fever,
traumatic injury, burns, surgery)
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Dietary Deficiency
• Kwashiorkor
• Protein energy malnutrition
• Occurs after child is weaned from breast feeding
• Not enough protein to support growth
• Clinically the child looks chubby, especially in
abdomen (fluid retention)
• Endemic in areas where diet lacks protein

Inc.anafflaefEleve
Inc.Alleeved.
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Kwashiorkor

Inc.anafflaefEleve
Inc.Alleeved.
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Marasmus
• Protein Energy Malnutrition
• Too few calories and insufficient protein
• Person appears to be wasting away
• Commonly seen in developing countries
• Seen in debilitating diseases such as cancer or
AIDS

Inc.anafflaefEleve
Inc.Alleeved.
1
Marasmus

Inc.anafflaefEleve
Inc.Alleeved.

Dietary Guides
• Recommended Dietary Allowances (RDAs)
• Relate to age, sex, weight
• Highest at birth and slowly decline into adulthood
• Men and women: 0.8 g/kg of desirable weight
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Dietary Guides
• First, convert lb. to kg.
• 200 lb divided by 2.2
• 90.9 kg (round to 91 kg)
• Convert your body weight (lb.) to kg

Calculating Protein Needs
• Calculation:
• Recommended protein intake = 0.8 g/kg
• 1 kg = 2.2 lb.
• Calculate: 220 lb. man
• 220 divided by 2.2 = 100 kg
• 100 kg multiplied by 0.8 g = 80 g protein
3
Calculating Protein Needs
• Calculation:
• Your body weight = _______ lb.
______ lb. divided by 2.2 = ______ kg
______ kg. multiplied by 0.8 = _______
** this equals # protein grams per day
recommended for you
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Dietary Guides, cont’d
• Dietary Reference Intakes (DRIs) from National
Academy of Sciences
• 10% to 35% of total caloric intake from protein
(children and adults)
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Summary
• Protein provides the body with its primary tissue-building
units, amino acids
• 20 common amino acids
• Nine of the 20 amino acids are essential in the diet
• Body can manufacture the remaining 11 amino acids
• Complete proteins are foods that supply all the
indispensable amino acids
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Summary, cont’d
• Complete proteins are usually of animal origin
• Plant foods are considered incomplete proteins because
they lack one or more of the indispensable amino acids
(with the exception of soy)
• Vegetarian diets can be strict with only plant proteins
(vegan), whereas other variations include dairy, egg, and
sometimes fish
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Summary, cont’d
• Clinical influences on protein include fever, disease,
surgery, or other trauma to the body
• Protein needs are calculated based on RDA standards
related to age, sex, and weight, which for both men and
women is set at 0.8 g of high quality protein per kilogram
of body weight per day
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Summary, cont’d
• Adjustments for protein intake are required for infants
and pregnant and breastfeeding women
• Adjustments also may be necessary for individuals
following a vegan diet
• Adjustments are made for critical illness
