after 2nd midterm amino acids

Question 1

Amino Acids

 Indispensable Amino Acids:

Answer 1

HIS, ILE, LEU, LYS, MET & CYS, PHE & TYR, THR, TYP, VAL
 AI set for infants 0-6 mo
 EAR & RDA for all other age and gender groups
- e.g., LYS for adults (19 y & older)
EAR = 31 mg/kg/d RDA = 38 mg/kg/d (“old” RDA/RNI 12 mg/kg/d) (almost 3 times as much due to new methodologie, used to use nitrogen balance to determine
 Values used to develop amino acid scoring patterns (in mg/g ptn) for
various ages based on the recommended intake of dietary ptn
 PDCAAS = protein digestibility-corrected amino acid scoring

why is arg not?????

Question 2

Adverse Effects of Amino Acids

Answer 2

 Certain amino acids have been studied extensively,
but the potential adverse affects of most amino acids
and their dose responses are not well documented.
Hence no value for the UL could be identified
 The failure to set UL values should not be taken to
imply that it is safe to consume very high amounts of
amino acids

Question 3

ESTIMATING AMINO ACID REQUIREMENTS

Answer 3

1) Nitrogen balance (and growth data)
2) Plasma amino acid concentrations
in 1980 came up
with these

3) Amino acid oxidation (direct) – fed/fasted states *
5) 24h amino acid balance
4) Indicator amino acid oxidation (indirect) – fed state *
6) Regression of N-balance

Question 4

NITROGEN BALANCE (NB)

Answer 4

NB = NI - ( UN + FN + MN )

take away one amino acid so that pro synthesis cant occur, there was therefore more FN, the last person to reach their requirement again was determined to be the requirement

Rose (1957) - adult males
Leverton (1959) - adult females
Nakagawa (1962) - children
 Holt & Snyderman (1967) - infants
Holt (1969) - infants

Question 5

PLASMA AMINO ACID CONCENTRATIONS

Answer 5

Relative concentration of limiting amino acid
will vary according to dietary supply
an increase in dietary tryptophan intake saw an increase in plasma tryptophan cancentration

no indicator of adequacy

Question 6

turnover/ aka flux

Answer 6

breakdown +intake = synthesis and excretion

Question 7

feed phe in low amount:

Answer 7

all taken up and none in the aa pool

Question 8

feed ph in high amount

Answer 8

starts to build up in pool because too much

more 13co2 being excreated

Question 9

why is other aa excreated when phe is low

Answer 9

because need alll of them to make protein, cant be stored so just excreate

Question 10

direct oxidation

Answer 10

the test oxidation

Question 11

indicator oxidation

Answer 11

looking at another oxidation

Question 12

New “Balanced” View on AA Requirements

Answer 12

Until recently NB gave lower estimates of
requirements than carbon-13
 Re-analysis of existing NB studies
 e.g., regression analysis
 New NB studies
 Confirm “new” amino acid requirements

Question 13

Issues for the Athlete: Amino Acids

Answer 13

 Indispensable Amino Acid (IAA) Requirements
 2 to 3 x higher than previous estimates (mg/kd/d)
 ensure IAA composition of dietary protein is 30%
 Eat good “quality protein” with sufficient energy
 Vegan athletes with limited lysine intake (lack of
legumes) may be at risk, however, increased energy
intake should compensate
 No need for amino acid supplementation