An isotopic study of the effect of dietary carbohydrate on the metabolic fate of dietary leucine and phenylalanine

Krempf, Michel; Hoerr, Robert; Pelletier, Véronique; Marks, Lisa; Gleason, Ray E.; Young, Vernon R.

doi:10.1093/ajcn/57.2.161

Cited by 33 publications

(16 citation statements)

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“…As far as whole splanchnic and peripheral anabolisms after a mixed soy protein meal are concerned, these results were found to be very consistent with those obtained using a previously developed model that had not been able to distinguish between the constitutive and exported parts of splanchnic proteins (27). In addition, and as shown in Table 5, model predictions for the regional metabolism of dietary N were validated in the light of findings available in the literature regarding the whole splanchnic (9,13,19,31,49,50) and peripheral (11,22,38,39,53,55) metabolism. In contrast, current knowledge concerning splanchnic interorgan metabolism and anabolism in the different splanchnic protein pools, which has mostly been obtained from experiments in animals (19,38,39,(48)(49)(50), remains unclear.…”

Section: Discussionsupporting

confidence: 83%

Contribution of plasma proteins to splanchnic and total anabolic utilization of dietary nitrogen in humans

Fouillet

Gaudichon

Bos

et al. 2003

American Journal of Physiology-Endocrinology and Metabolism

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Splanchnic tissues are largely involved in the postprandial utilization of dietary amino acids, but little is yet known, particularly in humans, about the relative contributions of different splanchnic protein pools to splanchnic and total postprandial anabolism. Our aim was to develop a compartmental model that could distinguish dietary nitrogen (N) incorporation among splanchnic constitutive, plasma (splanchnic exported), and peripheral proteins after a mixed-protein meal in humans. Eight healthy subjects were fed a single mixed meal containing 15N-labeled soy protein, and dietary N postprandial kinetics were measured in plasma free amino acids, proteins, and urea and urinary urea and ammonia. These experimental data and others previously obtained for dietary N kinetics in ileal effluents under similar experimental conditions were used to develop the compartmental model. Six hours after the mixed-meal ingestion, 31.5, 7.5, and 21% of ingested N were predicted to be incorporated into splanchnic constitutive, splanchnic exported, and peripheral proteins, respectively. The contribution of splanchnic exported proteins to total splanchnic anabolism from dietary N was predicted to be approximately 19% and to remain steady throughout the simulation period. Model behavior and its predictions were strongly in line with current knowledge of the system and the scarce, specific data available in the literature. This model provides the first data concerning the anabolism of splanchnic constitutive proteins in the nonsteady postprandial state in humans. By use of only slightly invasive techniques, this model could help to assess how the splanchnic anabolism is modulated under different nutritional or pathophysiological conditions in humans.

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Section: Discussionsupporting

confidence: 83%

Contribution of plasma proteins to splanchnic and total anabolic utilization of dietary nitrogen in humans

Fouillet

Gaudichon

Bos

et al. 2003

American Journal of Physiology-Endocrinology and Metabolism

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“…Other studies have provided indications of the important role of the splanchnic area in dietary nitrogen sparing by carbohydrates. Using an intraduodenal diet infusion, Krempf et al (14) reported that carbohydrates decreased the splanchnic uptake of dietary leucine and lowered whole-body leucine oxidation. This effect, which is not present for phenylalanine, may be dependent on the amino acid studied, particularly for amino acids that are taken up differently by the splanchnic area (34).…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, through their action on gastric emptying, carbohydrates in a meal modify the gastrointestinal kinetics, which are thought to play a key role in the subsequent metabolic utilization of dietary nitrogen (10)(11)(12)(13). In addition, the presence of carbohydrates in a meal is thought to modulate the splanchnic metabolism and may thus also differently modify dietary and endogenous nitrogen utilization by the gut and liver and subsequent nitrogen utilization by peripheral tissues (5,14). The present study aimed to investigate the effects of sucrose on postprandial deamination of dietary and endogenous amino acids in humans, with particular emphasis on bioavailability factors.…”

Section: Introductionmentioning

confidence: 99%

Postprandial modulation of dietary and whole-body nitrogen utilization by carbohydrates in humans

Mariotti

Mahé

Luengo

et al. 2000

The American Journal of Clinical Nutrition

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Background: Sucrose exerts a sparing effect on whole-body protein metabolism, mainly during the absorptive phase. Objective: We aimed to characterize the acute postprandial effect of addition of sucrose on deamination of dietary and endogenous nitrogen, with particular consideration being given to the effects of bioavailability. Design: Twenty-one subjects equipped with ileal tubes ingested 15 N-labeled soy protein combined with [13 C]glycine, with (n = 10) or without (n = 11) sucrose. Dietary and endogenous ileal flow of nitrogen were determined from the ileal effluents. The kinetics of dietary amino acid transfer to the blood were characterized by 13 CO 2 enrichment in breath and 15 N enrichment in plasma amino acids. Deamination of dietary and endogenous amino acid was determined from body urea, urinary nitrogen, and 15 N enrichment. Results:13 CO 2 recovery in breath and 15 N plasma amino acid enrichments were highly correlated (R 2 ≥ 0.95, P < 0.001, for both meals) and markedly delayed by sucrose (half-13 CO 2 recovery: 274 min compared with 167 min), whereas exogenous and endogenous ileal nitrogen kinetics and balances remained unchanged. Addition of sucrose halved the early (0-2 h) deamination peak of dietary nitrogen and reduced endogenous nitrogen oxidation over the first 4 h. Both were reduced by 18-24% over the 8-h period after the meal. Conclusions: Without changing the nitrogen absorptive balance, sucrose markedly affected the bioavailability profile, which is governed by gastric emptying. Endogenous and dietary nitrogen were not spared in the same way and over the same periods, showing that the metabolism of endogenous and dietary nitrogen may be affected differently by nutritional modulation, even if the effects are of a similar magnitude over the entire postprandial period.Am J Clin Nutr 2000;72:954-62.

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“…Tout d'abord, même à moyen terme, l'utilisation métabolique d'un ensemble d'acides aminés réagit de manière complexe à la composition en acides aminés et à la quantité d'acides aminés [43,44]. Ainsi il est vraisemblable qu'à court terme, l'orientation immédiate des acides aminés dans les voies métaboliques puisse être optimale pour un profil en acides aminés différent de celui qui assure la couverture des besoins à long terme et que ce profil puisse dépendre de nombreux facteurs comme l'apport énergétique associé [34,[45][46][47]. En particulier, l'homme possède d'assez fortes capacités d'accommodation à des variations qualitatives aiguës de l'apport protéique [26,48].…”

Section: Utilisation Métabolique Des Acides Aminés Alimentairesunclassified

Nutrition et santé : lipides et protéines d’origine végétale - De nouvelles données pour juger de la qualité des protéines végétales chez l’homme - Implications et perspectives

Mariotti

Tomé

2003

OCL

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Résumé : La qualité des protéines pour l'alimentation de l'homme est un sujet très ancien mais les différentes méthodes proposées jusqu'ici pour évaluer la qualité protéique ont été largement critiquées, pour des problèmes conceptuels et méthodologiques. Depuis quelques années des avancées ont pu être faites grâce à l'emploi d'isotopes stables dans la phase postprandiale chez l'homme. Ces techniques proposent des mesures fines et conceptuellement adaptées pour évaluer la qualité des protéines et explorer le concept de qualité protéique. Ces approches ont montré que les différences globales de qualités entre sources protéiques chez l'homme au bon statut nutritionnel sont bien plus faibles que cela n'était attendu. Parallèlement, la nature des protéines alimentaires pourrait avoir des effets métaboliques plus subtils, au niveau de certains tissus ou au niveau des voies métaboliques secondaires de certains acides aminés, dont il faudra mesurer l'étendue et évaluer les conséquences physiologiques et fonctionnelles. Summary :Protein quality for human nutrition is an old issue but the various methods aiming to assess protein quality have been criticized on theoretical and methodological ground. For the last years, stable isotope tracer-based methods in the postprandial state in humans have produced important progress. These refined techniques are strongly theoretically sounded for assessing protein quality and gaining further insight on the underlying concept. These methods have shown that protein sources exhibit global differences in protein quality in humans with adequate nutritional status that are far lower than expected based on usual methods. However, the nature of the dietary proteins could have some more subtle impact on tissues or secondary individual amino acid metabolic pathways, the final physiological and functional consequences of which will need to be evaluated.

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An isotopic study of the effect of dietary carbohydrate on the metabolic fate of dietary leucine and phenylalanine

Cited by 33 publications

References 0 publications

Contribution of plasma proteins to splanchnic and total anabolic utilization of dietary nitrogen in humans

Contribution of plasma proteins to splanchnic and total anabolic utilization of dietary nitrogen in humans

Postprandial modulation of dietary and whole-body nitrogen utilization by carbohydrates in humans

Nutrition et santé : lipides et protéines d’origine végétale - De nouvelles données pour juger de la qualité des protéines végétales chez l’homme - Implications et perspectives

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