ExercisePhysio
Guest
Reevaluation of the protein requirement in young men with the
indicator amino acid oxidation technique
ABSTRACT
Background: The current estimated protein requirements are based
on the nitrogen balance method, which has many limitations. An
alternate approach is needed to permit a reevaluation of protein
requirements.
Objective: The objective was to determine protein requirements in
men by using the indicator amino acid oxidation technique.
Design: Eight healthy men randomly received graded protein intakes
(0.10, 0.30, 0.60, 0.90, 1.2, 1.5 and 1.8 g/kg) of a crystalline amino acid mixture along with L-[1-13C]phenylalanine.
The mean protein requirement was determined by applying a biphase
linear regression crossover analysis on F13CO2 data, which identified
a breakpoint at the minimal rate of appearance of 13CO2 to
graded protein intakes.
Results: The mean and population-safe (recommended dietary
allowance; RDA) protein requirements were found to be 0.93 and
1.2 g kg1 d1, respectively. These requirements are comparable
with those estimated by the application of a biphase linear regression
model to the data from nitrogen balance studies (0.91 and
1.0 g kg1 d1, respectively). These requirements are 41% and
50% higher than the current recommendations for the estimated
average requirement (EAR) of 0.66 g kg1 d1 and the RDA of
0.80 g kg1 d1, as determined by applying a linear regression
model where it intersects the zero balance line.
Conclusion: The indicator amino acid oxidation technique defined
a protein requirement that is comparable with that estimated by the
application of a biphase linear regression model to nitrogen balance
data in the literature. Our data and the reanalysis of the preexisting
nitrogen balance data suggest that the current recommended protein
requirements are too low and require reassessment. Am J Clin
Nutr 2007;86:995–1002.
Edit: There is a middle ground there for sure.
Michael
indicator amino acid oxidation technique
ABSTRACT
Background: The current estimated protein requirements are based
on the nitrogen balance method, which has many limitations. An
alternate approach is needed to permit a reevaluation of protein
requirements.
Objective: The objective was to determine protein requirements in
men by using the indicator amino acid oxidation technique.
Design: Eight healthy men randomly received graded protein intakes
(0.10, 0.30, 0.60, 0.90, 1.2, 1.5 and 1.8 g/kg) of a crystalline amino acid mixture along with L-[1-13C]phenylalanine.
The mean protein requirement was determined by applying a biphase
linear regression crossover analysis on F13CO2 data, which identified
a breakpoint at the minimal rate of appearance of 13CO2 to
graded protein intakes.
Results: The mean and population-safe (recommended dietary
allowance; RDA) protein requirements were found to be 0.93 and
1.2 g kg1 d1, respectively. These requirements are comparable
with those estimated by the application of a biphase linear regression
model to the data from nitrogen balance studies (0.91 and
1.0 g kg1 d1, respectively). These requirements are 41% and
50% higher than the current recommendations for the estimated
average requirement (EAR) of 0.66 g kg1 d1 and the RDA of
0.80 g kg1 d1, as determined by applying a linear regression
model where it intersects the zero balance line.
Conclusion: The indicator amino acid oxidation technique defined
a protein requirement that is comparable with that estimated by the
application of a biphase linear regression model to nitrogen balance
data in the literature. Our data and the reanalysis of the preexisting
nitrogen balance data suggest that the current recommended protein
requirements are too low and require reassessment. Am J Clin
Nutr 2007;86:995–1002.
Edit: There is a middle ground there for sure.
Michael
(Note that it's not available freely - if you don't have a library that subscribes or can get the article via interlibrary loan, the $20 for 7-day access is probably your cheapest option.)