Exam 1: Proteins Flashcards
Proteins
- Contain nitrogen
- made up of 20 unique AA
- Order determines structure of peptide or protein
- held together by peptide bonds
- denatured by heat and extreme pH
Protein is made up of ____ nitrogen and also contains ____, _____, ____, and ____
16%, contains sulfur, phosphorus, iron and iodine
Essential/ Indispensable AA
-Phenylalanine
-Valine
-Troptophan
-Methionine
-Threonine
-Histadine
-Isoleucine
-Lysine
-Leucine
(PVT MT HILL)
Conditionally essential/ Indispensable AA
-Arginine
-Cysteine
-Glutamine
-Glycine
-Proline
-Tyrosine
We can make these but some conditions require we get them from the diet (become essential when AA precursor is deficient)
Nonessential/ Dispensable AA
- Alanine
- Asparagine
- Aspartic Acid
- Glutamic acid
- Serine
____patients cannot metabolize phenylketouria are are treated with a low phenylalanine diet
PKU
Phenylalanine is the precursor for
tyrosine (if low phenylalanine then tyrosine becomes required)
Anabolism
tissue building
Catabolism
tissue breakdown
Nitrogen is balanced if for every 1 g of N excreted in urine, ______ g of protein was consumed
6.25
Nitrogen intake by
supplements and diet
Nitrogen lost via
skin, feces, and urine (amount excreted can be measured in hospitalized patients)
Positive N balance
Amount consumed > amount excreted
- Occurs during periods of growth (pregnancy, muscle building, healing after illness)
- Required for somatic proteins (muscle mass) and visceral proteins (organ proteins)
Negative N balance
Amount excreted < amount consumed
- Inadequate dietary intake
- Illness, starvation, AA deficiency, Cancer, HIV/ AIDS, severe burns
Functions of protein
- Tissue building
- Fluid and pH balance
- Metabolism and transport
Protein is the _____ macro in the body
highest concentrated
______ helps maintain osmotic pressure
Albumin
The main intracellular buffer
proteins
Proteins are required in the immune system for
immunoglobulins and lymphocytes
Low protein diets increase the risk for
respiratory tract infections
The last resort for energy is
protein
up to ___% of energy is used to make ATP during endurance exercise
15%
Food allergies are normally caused by
proteins
a mild allergic reaction
rash, diarrhea, congestion and wheezing
Severe allergic reaction
anaphylactic shock (peanuts and fish)
Big 8 food allergies (causing 90% of food allergies)
Nuts (0.4-0.5%) Peanuts (0.6%) Shellfish (0.6% kids, 2.8% adults) Fish(0.2% kids, 0.5% adults) Eggs (1-2% kids) Wheat (0.8% in adults) Milk (1-2% kids) Soy (0.2%)
The most common way to diagnose a food allergy is
elimination diet
To confirm the findings of an elimination diet a _____ must be conducted
challenge test (causing symptoms to reappear)
The problem food should be avoided for ____ weeks on an elimination diet
2-4 (possibly 6 weeks if GI related)
The gold standard of food allergy testing is
oral food challenge
Oral Food Challenge (OFC)
- Elimination diet followed for at least 2 weeks prior
- Feeding of gradually increasing amounts of suspected foods under observation by a doctor over hours or days
- Must be prepared to treat anaphylactic shock
Skin prick tests
- Help narrow down foods tested in food challenge
- Negative result= no allergy
- Positive result = 50% likelihood of allergy
- used in conjunction with blood tests (sIgE) and clinical data
RAST (radioallergosorbent test)
- Blood sample tested for immune substance formed in response to an allergy
- not specific or reliable for food allergies
Unreliable tests
Mail-order, hair analysis, cytotoxic blood tests, sublingual or food injection tests
Body produces ____ in response to normal food consumed
IgG… SHOULD NOT be used to suggest an allergic reaction
____ ratios may be more predictive of allergy
IgE/ IgG4
Allergies likely to resolve in childhood
Milk, egg, wheat and soy
Allergies likely to persist to adulthood
peanut, tree nut, fish, shellfish
Peanut cross reactivity
most legumes in 5%
Tree nut cross reactivity
other tree nuts in 35% (higher in walnut/pecan, almond/hazel, cashew/pistachio)
Fish cross reactivity
other fish in 50%
Shellfish cross reactivity
other shellfish in 75%
grain cross reactivity
other grains in 20%
Milk cross reactivities
goat/sheep milk in >90%, horse milk in 5%, beef in 10%
Excellent protein sources
- red meat
- poultry
- fish and shellfish
- eggs
- dairy
- soy
- amaranth
- quinoa
Good protein sources
- legumes (beans, lentils, and peas)
- nuts and seeds
1 oz of meat, eggs, or milk =
about 7 g protein
1/2 cup soybeans
13 g protein
1/2 cup kidney beans
21 g protein
1 oz. almonds
6 g protein
complete protein sources
- contain all 9 indispensable AA
- All animal proteins, except gelatin
- soy, amaranth, and quinoa
Incomplete protein sources
- deficient in 1 or more of the 9 indispensable AA
- most plants
Corn is deficient in
lysine and tryptophan
wheat is deficient in
lysine
Rice is deficient in
lysine
Legumes are deficient in
methionine (beans, peanuts, and peas)
Eating _____ sources of proteins throughout the day is ________
several, necessary for adequate protein combining (especially vegetarians)
Benefits of vegetarian diets
Decreased incidence of cancer, heart disease, diabetes, and hypertension
Nutrients of concern in a vegetarian diet
Vitamin B12 (only in animal products)
Vitamin D (main source in cow’s milk)
Calcium (Oxalated can bind Ca, Broccoli or Ca- fortified foods)
Iron (RDA is 1.8 times higher for vegetarians)
Zinc (plants are high in phytates that bind zinc)
Omega-3s
Protein digestion in stomach
HCL denatures protein and activates pepsin
Pepsin digests protein into smaller polypeptides
Protein digestion in Small intestine
Enzymes from pancreas and SI further digest to AA, di, and tripeptides, then absorbed by active transport
Pancreatic zymogens:
trypsinogen (activated by enterkinase)
chmotrypsinogen
procarboxypeptidase
SI zymogens
proaminopeptidase, dipeptidase
Factors influencing body’s protein requirement
- tissue growth
- protein quality
- additional needs due to illness or disease
Protein Digestibility Corrected Amino Acid Score (PDCAAS)
PDCAAS= % digestibility X (mg limiting AA in test protein/ mg limiting AA in reference protein)
*Reference protein is either milk or egg
Limiting protein is the AA found in _____ quantity
smallest
Protein Efficiency Ratio (PER)
PER= Gain in body weight (g) / Grams of protein consumed
Biological Value (BV)
Measure of N retained in body vs absorption/ excretion
- the higher the BV, the closer the AA profile is to what the body requires
Illness or disease causes an _____ protein require
increased; fever, burns, catabolic tissue breakdown, inflammatory conditions (IBD), post-surgery
Protein- Energy Malnutrition (PEM)
Kwashiorkor or marasmus
Kwashiorkor
- Adequate Cal, but lack protein
- Edema, fatty liver
Marasmus
- Emaciated
- Lack Cal and protein
Causes of excess protein intake
- Animal protein foods are high in saturated fat
- Filling up on high protein foods leaves little room for plants
- Excess protein may result in inflammation and apoptosis of kidney cells
Percent of men and women are actively trying to lose weight
33% of men, 46% of women
-20% of those are following recommendation of eat less and exercise
High protein diet for weight loss
- Higher in total fat, saturated fat, and cholesterol
- lower in fiber and antioxidants
- initial weight loss is due to fluid loss
AMDR for protein
10-35% of energy
RDA for protein
- 8 g/kg body weight
0. 36 g/lb body weight
energy from proteins
4 kcal/g
Most american get 15-17% of their energy from
protein
Women= about 70 g/d
men= 100 g/day
Guidlines for protein intake
- Variety (seafood, lean meat, poultry, eggs, beans, peas, nuts)
- Seafood at least 8 oz/ week
- choose low sodium options
What percent of newly diagnosed celiac patients develop metabolic syndrome after 1 year of being gluten-free?
30%
Gluten-free diets are often lacking _______ and higher in ____ and ___
several B vitamins, higher in saturated fat and sodium
