Document Detail

The total branched-chain amino acid requirement in young healthy adult men determined by indicator amino acid oxidation by use of L-[1-13C]phenylalanine.
MedLine Citation:
PMID:  12730426     Owner:  NLM     Status:  MEDLINE    
Previous recommendations for branched-chain amino acids (BCAA), based on nitrogen balance studies, were found to be low in a series of stable isotope-labeled amino acid studies. The BCAA requirement was increased in the new dietary reference intake (DRI) report on the basis of a series of stable isotope studies examining the requirement of leucine and valine individually, but not isoleucine. To reduce the possibility of interactions among these amino acids and imbalances in the mixture affecting the estimate of requirements, we decided to determine the requirement for the total BCAA of young healthy adult men, receiving a mixture of BCAA based on the proportion of these amino acids in egg protein, by use of indicator amino acid oxidation. Seven men were assigned to receive nine graded intakes of a BCAA mixture in random order: 34, 50, 66, 80, 100, 120, 140, 160 and 180 mg/(kg. d). The rate of release of (13)CO(2) from the oxidation of L-[1-(13)C]phenylalanine (F (13)CO(2)) was measured and a two-phase linear regression crossover model was applied to determine total BCAA requirement. The mean requirement and population-safe level (upper limit of 95% confidence interval) of the total BCAA were 144 and 210 mg/(kg. d), respectively. Based on the balance of BCAA in egg protein, our estimate for the mean leucine requirement is 55 mg/(kg. d), which is substantially higher than the 34 mg/(kg. d) recommended by the DRI.
Roya Riazi; Linda J Wykes; Ronald O Ball; Paul B Pencharz
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of nutrition     Volume:  133     ISSN:  0022-3166     ISO Abbreviation:  J. Nutr.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-05-05     Completed Date:  2003-06-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1383-9     Citation Subset:  IM    
Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3E2.
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MeSH Terms
Amino Acids, Branched-Chain / metabolism*
Body Composition
Carbon Isotopes
Energy Intake
Isoleucine / metabolism
Isotope Labeling / methods
Leucine / metabolism
Nitrogen / metabolism
Nutritional Requirements*
Phenylalanine / metabolism*
Tyrosine / metabolism
Valine / metabolism
Reg. No./Substance:
0/Amino Acids, Branched-Chain; 0/Carbon Isotopes; 55520-40-6/Tyrosine; 61-90-5/Leucine; 63-91-2/Phenylalanine; 7004-03-7/Valine; 73-32-5/Isoleucine; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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