MargiAnne Isaia, MD MPH

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Advanced Nutrition
Proteins 2
MargiAnne Isaia, MD MPH
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• GLUCOGENIC AND KETOGENIC AMINO ACIDS
• Definitions
• Glucogenic yield pyruvate or one of the
  intermediates of the Citric Acid cycle
• Ketogenic yield Acetyl CoA or intermediates of
  fatty acid oxidation
• Ketogenic and glucogenic amino acids
• Purely ketogenic (Leucine)
• Both ketogenic and glucogenic (Isoleucine,
  Lysine, Phenylalanine, Tyrosine, Tryptophan)
• Purely glucogenic (Alanine, Serine, Glycine,
  Cysteine, Aspartic Acid, Asparagine, Glutamic
  Acid, Glutamine, Arginine, Histidine, Valine,
  Theronine, Methionine, Proline)

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PROTEINS AND GENERAL METABOLISM
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• CONVERSION OF AA TO SPECIALIZED PRODUCTS
• HEME AND HEMOGLOBIN
• Heme (porphyrins)
• - Iron containing pigment of Hemoglobin and
  cytocromes
• made of Glycine Succinyl CoA
• CREATINE, PHOSPHOCREATINE AND CREATININE
• Creatine
• - made in the liver and muscle
• Glycine Arginine Methionine
• phosphorilated to Phosphocreatine
• (Phosphocreatine high energy bonds)
• - Phosphocreatine Creatinine (some lost in
  urine)

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CONVERSION OF AA TO SPECIALIZED
PRODUCTS Carnitine Fatty Acyl
carrier across the mitochondrial membrane
- synthesized from e-N,N,N-
trimethyllysine Neurotransmitters
Acetylcholine from Serine and
Choline acylation by Acetyl CoA
Catecholamines ( Epinephrine,E, and
Norepinephrine, NE) - from Tyrosine
through Dihydroxy-phenilalanine ,DOPA, to
Dopamine - Dopamine ( dopamine
hydroxylase , Vitamin C as coenzyme) to NE
- NE methylated (S-Adenosylmethionine, donor
of methyl group) to E Serotonin
(5-hydroxythyptamine) - made of
Tryptophan - found in intestinal
mucosa, platelets, central nervous system
- inhibits food intake
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CONVERSION OF AA TO SPECIALIZED PRODUCTS Other
compounds Polyamines ( decarboxylation of
Ornithine) Melanin, from Tyrosine Purines and
Pyrimidines, from Glycine, Glutamine and
Aspartate Taurine, from Cysteine Glutathione,
from Glycine, Cysteine and Glutamate
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CONVERSION OF AMINO ACIDS TO SPECIALIZED PRODUCTS
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• POSTPRANDIAL NITROGEN
• AND AMINO ACID UTILIZATION
• Metabolism of Amino Acids occurs at different
  rates
• during the post absorptive, prandial and
  postprandial periods of the 24-hr day
• Nitrogen distribution after protein ingestion
• uptake by the splanchnic bed into the
  portal-drained viscera (i.e., the intestine,
  pancreas, spleen and stomach)
• Utilization by the body for protein synthesis
  depends on
• quality of protein
• Size of meals
• Utilization by the gut
• Energy
• Secretory protein synthesis (glycoproteins) -
  role of Threonine
• Synthesis of Citrulline and Glutathione

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• BLOOD LEVELS OF AMINO ACIDS
• Blood levels are influenced by dietary AA intake
• Blood amino acid levels after meals reflect
  protein and AA eaten
• In the post absorptive state
• Blood AA levels are stable and characteristic of
  species
• There is a net release of AA from muscle to
  plasma
• There is uptake by kidneys for gluconeogenesis
  and ammonia formation
• Blood levels of AA are sometimes used to estimate
  requirement

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• ROLE OF THE LIVER
• Monitors absorbed Amino Acids (AA) and adjusts
  rate of metabolism according to the body needs
• Increased protein intake results in higher
  activity of liver enzymes which handle AA. Liver
  breaks down most AAs except branched chain.
• There is a difference in the metabolism of
  dispensable versus indispensable AA by the
  liver depending on the diet
• There is a direct correlation between the amount
  of protein in the diet and catabolism of
  dispensable amino acids
• Indispensable amino acids catabolism increases
  only when the diet provides substantial amounts
  of those amino acids

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SKELETAL MUSCLE The Alanine cycle ( Cori
cycle) The release of AA from muscle does not
reflect the AA profile of muscle. Two-third of
AA released from muscle are Glutamate and
Alanine. Branched chain AA undergo transamination
and then they are oxidized in muscle tissue for
energy.
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PROTEIN QUALITY Protein quality depends on -
The relative content of the individual
indispensable amino acids in a food protein - The
metabolic availability of the individual
indispensable amino acids in a food protein(or
the digestibility of the food protein) - Relative
amounts of dispensable vs. indispensable AA -
Presence of toxic materials trypsin
inhibitors, allergenic stimuli
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PROTEIN QUALITY Complete protein A food protein
containing the essential amino acids in an
adequate amount and proportion to support the
growth of young lab animals. Examples of complete
proteins milk, meat, egg, soy Incomplete
proteins A food protein low in one or more
essential amino acids, i.e., proteins that
sustain life of young animals but do not support
growth. Examples of incomplete proteins beans,
peas, nuts, seeds, grains
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PROTEIN QUALITY Limiting amino acid The
essential amino acid with the lowest proportion
in a given protein food. Complementary
proteins Two or more incomplete protein that
produce a complete protein when combined. The
limiting amino acid in one food is complemented
by the presence of that amino acid in the other
food(s).
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METHODS FOR EVALUATING PROTEIN QUALITY Biological
test (historical importance) - Protein
Efficiency ratio (PER) weight gain per gram
of protein consumed - Net Protein Utilization
(NPU) difference protein fed group and
protein-free fed group - Biological Value
(BV) the fraction of absorbed nitrogen
retained Scoring methods - Amino Acid
score amount of essential AA in the food
protein compared with a reference
protein ( eggs, breast milk etc) - Protein
digestibility-corrected AA score
(PDCAAS) compares the essential AA of a food to
that of the FNB/IOM AA pattern and
adjusts with the digestibility of protein
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PROTEIN DIGESTIBILITY Protein digestibility is
determined 2 ways Apparent protein
digestibility The of nitrogen intake that does
not appear in the feces of subjects on a diet
containing the test protein True
digestibility Estimates of true protein
digestibility taking into account the amount of
nitrogen in feces when none is present in the
diet (protein-free diet) ( True digestibility of
soy protein is 97 and is comparable with that
for egg protein)
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PROTEIN DIGESTIBILITY FACTORS Nature of food
protein Nature of cells wall Nature of the
protein linkage Polyphenols and other food
constituents Food preparation and cooking
methods Heat treatment (the Maillard reaction
between protein and CHO occurs under conditions
of dry heat reduced digestibility) Cooking
increases protein digestibility by destructing
anti-nutrients (protease inhibitors, tannins,
saponins, phytates etc )
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PROTEIN DIGESTIBILITY CORRECTED AA SCORE
PDCAAS PDCAAS scores are usually calculated for
Lysine, Sulfur AA, Threonine, and
Tryptophan (Lysine is the most limiting AA in
protein of plant food) PDCAAS of a food is the
lowest score obtained using the limiting AA FDA
labeling of DV of protein is based on the
PDCAAS method of determining protein quality
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PROTEIN DIGESTIBILITY CORRECTED AA SCORE
PDCAAS Data needed for calculation AA
composition of food in mg AA per gram
protein True digestibility of the food protein
() FNB/IOM AA scoring pattern ( mg AA per gram
protein) The AA with the lowest score is the
score for digestibility Amino Acid score and
plant protein quality In plant-based diets
combination of protein from different
food categories results in high PDCAAS (protein
complementation lentils rice)
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AMINO ACID CONTENT OF DIFFERENT FOOD PROTEIN
SOURCES The indispensable AA that are likely to
be the most limiting in plant protein
food Lysine lower in all plant protein
foods Sulfur-containing AA lower in legumes and
fruits Threonine lower in cereals and
fruits Tryptophan lower in legumes, cereals,
fruit, animal foods Protein quality in world
wide nutrition wheat Lysine limiting AA -
fortification needed rice Lys Thre limiting
AA - fortification needed corn Lys Try
limiting AA - fortification needed oats no
limiting AA amaranth surplus of Lys and
Try buckwheat no limiting AA surplus of Try

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PROTEIN AND AA REQUIREMENTS AND PROTEIN QUALITY
CONSIDERATIONS The requirement for dietary
protein consists of two components 1. The
requirement for the nutritionally indispensable
AA under all conditions and AA conditionally
indispensable under specific physiological and
pathological conditions 2. The requirement for
nonspecific Nitrogen for the synthesis of the
nutritionally dispensable AA and other
physiologically important Nitrogen-containing
compounds The efficiency with which a given
source of food protein is utilized in support of
an adequate state of nutritional health depends
on - the physiological requirements for the
indispensable AA and total Nitrogen - the
concentration of specific AA in the source of
interest These two characteristics must be
taken into account for protein nutritional
quality. Special attention for children and
infants on diets containing a single food protein
source or a limited number of protein sources
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P R O T E I N S
PROTEINS
DAILY VALUE
Daily intake
depends on age
- Infant 6 mo
2g / per kg body weight
-
-
- adult
0.8g / per kg body weight (0.35g/pound)
depends on health status
depends on special conditions
ADULT
45-60g /day (2 ounces of pure protein adult
170lb)
(15 of total daily amount)
60 CHO (45-65 )
25 FAT (20-35 )
15 PROTEIN (10-15 )
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FACTORS WHICH INFLUENCE PROTEIN
REQUIREMENTS Those accounted for by the
RDA Physiological state growth, pregnancy,
lactation, elderly. Body weight Those not
accounted for by the RDA Infections, fevers,
burns, surgical trauma, accidents, etc. Muscular
activity, exercise Importance of the ratio g
total essential AA to total N in the diet
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PROTEIN SUPPLEMENTATION AND COMPLEMENTATION The
efficiency of dietary protein utilization depends
on - AA pattern of protein in diet - Intake of
Nitrogen - Overall intake of nutrients ( total
calories) - Physiological state Supplementation
occurs when two or more proteins are fed and
there is an increase in the total protein being
fed Complementation occurs when two or more
proteins are fed and the total level of dietary
protein is kept constant Protein
complementation importance in plant-based diet
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PROTEIN COMPLEMENTATION There are 4 types of
responses observed upon feeding various
combinations of two or more proteins at a
constant level of total dietary protein Type I
(no effect) the protein sources combined have
a common essential AA deficiency of the same
extent ( ex. corn peanut, both Lys
deficiency) Type II ( partial complementation) th
e protein sources combined have a common
essential AA deficiency, but in quantitatively
different amount ( corn black beans) Type III
(true complementation) one of the protein
sources has a considerably higher concentration
of the most limiting AA in the other protein
there is a synergistic effect the protein
quality of the best mix exceeds that of each
component alone ( 60 corn 40 soy) Type IV
(supplementation) both protein sources have a
common AA deficiency. The protein component
giving the highest value is the one containing
a higher concentration (beef textured soy
protein, beans potato)
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VEGETABLE PROTEINS Protein digestibility
generally lower than that of animal
proteins . Preparation or processing influence
protein digestibility and AA availability. Cereal
s and legumes intended for human feeding are
cooked or processed - enhanced palatability and
acceptance Nutritional value related with
components in the food temperature, duration
of heating, presence/ absence of moisture
(Boiling in water improves protein quality,
toasting of dry heating reduces protein
quality) Nutritional interferences amylase
inhibitors interfere with starch digestion (
in most legumes, inactivated by prolonged
boiling) tannins, phenolic compounds form less
digestible complexes ( found in most legumes)
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P R O T E I N S
PROTEINS
CLASSIFICATION
Animal proteins
Characteristics

• AA loaded with fats (Cholesterol saturated fats)

• No fibers

Health destroying

• Arthrosclerosis with all its complications

• Premature aging

• Osteoporosis

• Cancer ( immunity)

• Decreased endurance (high protein diet)

• Early puberty children grow bigger, develop
  faster

• Shorter life span (life span after flood)

• Burden on the kidney (excess proteins)

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P R O T E I N S
PROTEINS
CLASSIFICATION
Plant proteins
Characteristics

• All essential AA provided

• Easily available through complementary AA
  association

• Important source of Arginine

• Loaded with fibers

Health promoting

• ORIGINAL PLAN

• Physical endurance (athletes)

• Mental wellness

• Daniel

-Delayed aging

• Live longer better

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P R O T E I N S
PROTEINS
S O U R C E S
Animal proteins
Plant proteins
- Legumes vegetables
- meat
- eggs
- nuts seeds
- milk dairy products
- grains
Complementary AA association
Wheat all legumes (soy, garbanzo, lentils,
peas, all beans)
Corn beans, nuts, soybean
Rice beans, nuts, lentils
Oats nuts
Rye soybean
Sesame seeds garbanzo beans, soy
Legumes nuts
Legumes seeds
Special diet
Caribbean - black beans rice
China rice soybean
Mexico corn pinto beans
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SOY BEANS Advantages protein quality Limiting
AA score 100 decrease Cholesterol
preferred in the End Stage Renal Disease
phyto-chemicals content, Estrogen-like
effects (Genistein, Daidzein)
anti-oxidant effect anti-cancer
effect Disadvantages infant formula allergenic
food (1 of infants) Estrogen-like
effects ?? protease inhibitor
phytate content effect on
thyroid if a deficient iodine diet
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VEGETABLE PROTEIN REALITY Usual dietary
combinations of proteins are complete specific
food proteins may be low in specific AA Quality
depends on the source and dietary mixture of
plant proteins can be equivalent to
high-quality animal proteins Proteins do not need
to be consumed at the same time, the balance over
a day is of greater importance Digestibility
can vary according to source and food
preparation digestibility can be high The
intakes and balance of intakes of indispensable
AA and Nitrogen are crucial and can be
adequately met from plant or plant and animal
sources There is no evidence that AA imbalances
per se are important possible imbalances can be
created by inappropriate AA supplementation, but
this is not a practical problem
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UNDESIRABLE METABOLIC EFFECTS OF HIGH DIETARY
PROTEIN INTAKE IN ADULT HUMANS Glomerular hyper
filtration and hyperemia Acceleration of chronic
kidney disease Increased proteinuria, diuresis,
natriuresis and kaliuresis Blood pressure
changes Increased risk for nephrolithiasis - h
oxalate and glycolate excretion Various metabolic
alteration - h Insulin secretion, h hepatic
Glucose output, and i Insulin senstivity
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CLINICAL EFFECTS OF INADEQUATE PROTEIN
INTAKE Protein deficiency has adverse effects
on all organs In infants and young children -
harmful effects on the brain, - longerterm
effects on brain function Immune system -
higher risk of infections Gut mucosal function
and permeability - affects absorption and makes
possible bacterial invasion from the gut,
resulting in septicemia Kidney function -
glomerular and tubular function
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CLINICAL ASSESSMENT OF PROTEIN NUTRITIONAL
STATUS No
single parameter is completely reliable Infants
and children failure to grow (length or
height) Urinary creatinine excretion used as a
reflection of muscle mass Serum proteins
particular limitations -albumin affected by
protein losing entheropathy, renal loss,
burns, liver diseases clinical use severe
malnutrition -transferrin affected by Iron
deficiency and by infection clinical use
limited- chronic deficiency -pre-albumin affect
ed by vitamin A deficiency clinical use acute
depletion -retinol-binding protein affected by
vitamin A deficiency clinical use acute
depletion
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REFERENCES Shils M et al, Modern Nutrition in
Health and Disease, 10th Edition www. Pubmed.org

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