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This Article Full Text Full Text (PDF) Supplemental data All Versions of this Article: 90/4/1011    most recent ajcn.2009.27548v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Deglaire, A. Articles by Bos, C. PubMed PubMed Citation Articles by Deglaire, A. Articles by Bos, C. Agricola Articles by Deglaire, A. Articles by Bos, C.

Hydrolyzed dietary casein as compared with the intact protein reduces postprandial peripheral, but not whole-body, uptake of nitrogen in humans^1,2,3,4

¹ From the INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France (AD, CF, HF, CG, C Boutry, RB, DT, and C Bos); AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France (AD, CF, HF, CG, C Boutry, RB, DT, and C Bos); Riddet Institute, Massey University, Palmerston North, New Zealand (AD and PJM); and the Department of Gastroenterology, Avicenne Hospital, CRNH-IdF, Bobigny, France (GA and RB).

² Presented in part in abstract form at Experimental Biology, San Diego, CA, 4–9 April 2008.

³ Supported by grants from the INRA (France) and the Riddet Institute (NZ).

⁴ Address correspondence to C Bos, UMR914 INRA-AgroParisTech Nutrition Physiology and Ingestive Behavior, AgroParisTech, 16 rue Claude Bernard, F-75005 Paris, France. E-mail address: cecile.bos{at}agroparistech.fr.

Background: Compared with slow proteins, fast proteins are more completely extracted in the splanchnic bed but contribute less to peripheral protein accretion; however, the independent influence of absorption kinetics and the amino acid (AA) pattern of dietary protein on AA anabolism in individual tissues remains unknown.

Objective: We aimed to compare the postprandial regional utilization of proteins with similar AA profiles but different absorption kinetics by coupling clinical experiments with compartmental modeling.

Design: Experimental data pertaining to the intestine, blood, and urine for dietary nitrogen kinetics after a ¹⁵N-labeled intact (IC) or hydrolyzed (HC) casein meal were obtained in parallel groups of healthy adults (n = 21) and were analyzed by using a 13-compartment model to predict the cascade of dietary nitrogen absorption and regional metabolism.

Results: IC and HC elicited a similar whole-body postprandial retention of dietary nitrogen, but HC was associated with a faster rate of absorption than was IC, resulting in earlier and stronger hyperaminoacidemia and hyperinsulinemia. An enhancement of both catabolic (26%) and anabolic (37%) utilization of dietary nitrogen occurred in the splanchnic bed at the expense of its further peripheral availability, which reached 18% and 11% of ingested nitrogen 8 h after the IC and HC meals, respectively.

Conclusions: The form of delivery of dietary AAs constituted an independent factor of modulation of their postprandial regional metabolism, with a fast supply favoring the splanchnic dietary nitrogen uptake over its peripheral anabolic use. These results question a possible effect of ingestion of protein hydrolysates on tissue nitrogen metabolism and accretion. This trial was registered at clinicaltrials.gov as NCTNCT00873951.