Protein quality and needs

Question 1

Protein quality depends on ____ and _____

Answer 1

digestibility and indispensable amino acid composition

Question 2

collagen/gelatin is not a complete protein as it lacks

Answer 2

Tryptophan

Question 3

animal proteins tend to be -___ to ____% digestible

Answer 3

Animal: 90-99%
Plants: 70-90%

Question 4

PDCAAS is largely used for

Answer 4

labeling purposes

Question 5

how does PDCAAS measure protein quality

Answer 5

compares the amount of limiting AA for a test protein to the same amount of the AA in 1g of reference protein
-values range from 0-1 and are truncated

Question 6

How does PDCAAS measure digestibility?

Answer 6

Through fecal nitrogen
-criticized because accounts for nitrogen from test protein and endogenous protein from digestive secretions and cells
-also doesn’t account for bacterial utilization of nitrogen

Question 7

how does DIAAS measure protein quality

Answer 7

allows for the ranking of different protein sources based on the ability to meet indispensable A requirements

mg of the same indispensable amino acid in 1g of the reference protein

Question 8

how does DIAAS measure digestibility

Answer 8

in the ileum, eliminates the impact of protein nitrogen by gut microbiota
-allows for score greater than 100

Question 9

Chemical or AA Score

Answer 9

method to determine AA composition of a test protein
-lab based measure using amino acid analyzer or HPLC
-only the indispensable AA content of a test protein is determined, compare that value with that of a reference protein
-Amino acid with the lowest score on a percentage basis in relation to a reference protein becomes the first limiting amino acid

Question 10

Biological value assesses

Answer 10

protein quality

Question 11

how does biological value work

Answer 11

measures how much nitrogen is retained in the body for the maintenance of growth rather than just absorbed
-most often used in animal studies
1. Fed nitrogen free diet for 7-10 days
2. Fed diet containing test protein in equal amounts to protein requirements for 7-10 days
3. Nitrogen excretion measured in both phases and compared

Question 12

Net protein utilization

Answer 12

method similar to biological value but relies on nitrogen consumed rather than nitrogen absorbed, no deduction of fecal levels of nitrogen excreted

Question 13

Nitrogen balance equation

Answer 13

ingested protein (g)/6.25= ingested nitrogen (g)

Question 14

Describe the nitrogen balance status

Answer 14

nitrogen losses occur in urine, feces, and skin
-in clinical settings, nitrogen losses often estimated
-fecal and insensible (hair, skin, nails) loses around 2g total
-urinairy urea nitrogen can be measured but typically add 2g of this value to account for loses of other non-urea nitrogen compounds in the urine

Question 15

RDA, AMDR, AND UL for protein

Answer 15

RDA= .8g/kg/day
AMDR = 10-35%
No UL

Question 16

Describe the claim that too much protein leaches calcium from bones

Answer 16

Reality: calcium excretion does increase as protein intake increases, but so does calcium absorption” no net loss of calcium as protein comprises a large portion of bone volume

Question 17

Describe the claim that too much protein is hard on the kidneys

Answer 17

reality: no evidence that protein is harmful, difficulties handling protein and nitrogen excretion don’t present until late stages of kidney diseases
-in chronic kidney disease, prtoien should be limited at higher stages when glomular filtration rate falls
-recommended .6-.8g

Question 18

Describe arginine’s role with stress

Answer 18

Arginine is conditionally essential and becomes essential under conditions of stress and catabolism because the capacity for endogenous synthesis surpassed by needs
-sepsis, burns

Question 19

Describe glutamines role in stress

Answer 19

Glutamine is non essential and can be produced by conversation of glutamic acid
-precursor to arginine as well as for NAD and glutathionine
-endogenous protein impaired in situations of abnormal muscle protein metabolism
-low plasma level in ICU patients found to be independent predictor of mortality

Question 20

Formula for nitrogen balance

Answer 20

(protein intake (g) / 6.25) - (UUN+2g+2g)