Document Detail

Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement.
MedLine Citation:
PMID:  17093159     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The in vivo quality of milk protein fractions has seldom been studied in humans. OBJECTIVE: Our objective was to compare the postprandial utilization of dietary nitrogen from 3 [(15)N]-labeled milk products: micellar caseins (MC), milk soluble protein isolate (MSPI), and total milk protein (TMP). DESIGN: The macronutrient intakes of 23 healthy volunteers were standardized for 1 wk, after which time the subjects ingested a meal containing MC (n = 8), MSPI (n = 7), or TMP (n = 8). [(15)N] was measured for an 8-h period in plasma amino acids, proteins, and urea and in urinary urea. RESULTS: The transfer of dietary nitrogen to urea occurred earlier after MSPI ingestion than after MC and TMP ingestion, and concentrations remained high for 8 h, concomitantly with higher but transient hyperaminoacidemia and a higher incorporation of dietary nitrogen into plasma amino acids. In contrast, deamination, postprandial hyperaminoacidemia, and the incorporation of dietary nitrogen into plasma amino acids were lower in the MC and TMP groups. Finally, total postprandial deamination values were 18.5 +/- 2.9%, 21.1 +/- 2.8%, and 28.2 +/- 2.9% of ingested nitrogen in the TMP, MC, and MSPI groups, respectively. CONCLUSIONS: Our results confirm the major role of kinetics in dietary nitrogen postprandial utilization and highlight the paradox of MSPI, which, despite its high Protein Digestibility Corrected Amino Acid Score, ensures a rate of amino acid delivery that is too rapid to sustain the anabolic requirement during the postprandial period. Milk proteins had the best nutritional quality, which suggested a synergistic effect between soluble proteins and caseins.
Magali Lacroix; Cécile Bos; Joëlle Léonil; Gheorge Airinei; Catherine Luengo; Sophie Daré; Robert Benamouzig; Hélène Fouillet; Jacques Fauquant; Daniel Tomé; Claire Gaudichon
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of clinical nutrition     Volume:  84     ISSN:  0002-9165     ISO Abbreviation:  Am. J. Clin. Nutr.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-11-09     Completed Date:  2006-12-14     Revised Date:  2007-07-11    
Medline Journal Info:
Nlm Unique ID:  0376027     Medline TA:  Am J Clin Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1070-9     Citation Subset:  AIM; IM    
UMR INRA 914, Physiology of Nutrition and Feeding Control Unit, Institut National Agronomique Paris-Grignon, Paris, France.
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MeSH Terms
Amino Acids / blood,  metabolism*,  urine
Area Under Curve
Blood Urea Nitrogen
Breath Tests
Calorimetry, Indirect
Carbon Dioxide / analysis
Caseins / metabolism*,  pharmacokinetics
Milk / metabolism*
Milk Proteins / metabolism*,  pharmacokinetics
Nitrogen Isotopes
Nutritive Value
Postprandial Period
Urea / urine
Reg. No./Substance:
0/Amino Acids; 0/Caseins; 0/Milk Proteins; 0/Nitrogen Isotopes; 124-38-9/Carbon Dioxide; 57-13-6/Urea
Comment In:
Am J Clin Nutr. 2007 Jun;85(6):1664; author reply 1664-5   [PMID:  17556707 ]

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

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