Clinical–Alimentary Tract
Ileal losses of nitrogen and amino acids in humans and their importance to the assessment of amino acid requirements☆,☆☆,★
Section snippets
Experimental meals
We compared 2 different purified protein test meals, fed to the subjects on the morning of the experimental day: a milk protein meal (295 mmol N) and a soy protein meal (316 mmol N), providing 502 kJ. The meals consisted of 30 g of milk or soy protein isolate stirred into water to obtain a final volume of 500 mL. Dietary protein purification and 15N labeling of milk and soy were performed as described in our previous studies.16, 17, 22 Briefly, milk was obtained from a lactating cow given
Endogenous and dietary nitrogen in the ileal effluents
The flow rate of endogenous nitrogen and the cumulative appearance of dietary nitrogen in the ileal effluents are shown in Figure 1.
The endogenous flow rate was enhanced duringDiscussion
The present study allowed further characterization of nitrogen compounds in ileal intestinal effluents in humans. To the best of our knowledge, this study also provides the first data on individual amino acid losses of both endogenous and dietary origin in healthy human subjects. We demonstrated that an IAA amount corresponding to 40%–100% of current IAA requirements20 is recovered at the terminal ileum and thus should be considered when estimating IAA requirements.
Acknowledgements
The authors thank ARILAIT Recherches for their comments on the manuscript and the staff of the DIfE Protein Metabolism Unit for the excellent technical assistance with 15N gas chromatography-combustion-isotope ratio mass spectrometry measurements.
References (48)
Contribution of microbial amino acids to amino acid homeostasis of the host
J Nutr
(2000)- et al.
The 24-h pattern and rate of leucine oxidation, with particular reference to tracer estimates of leucine requirements in healthy adults
Am J Clin Nutr
(1994) - et al.
Recent advances in methods of assessing dietary amino acid requirements for adult humans
J Nutr
(1995) - et al.
Amino acid losses in ileostomy fluid on a protein-free diet
Am J Clin Nutr
(1994) - et al.
Gastroileal nitrogen and electrolyte movements after bovine milk ingestion in humans
Am J Clin Nutr
(1992) - et al.
The use of 15N-labeled dietary proteins for determining true ileal amino acid digestibilities is limited by their rapid recycling in the endogenous secretions of pigs
J Nutr
(1996) - et al.
Whole-body nitrogen and splanchnic amino acid metabolism is different in rats fed mixed diets containing casein or its corresponding amino acid mixture
J Nutr
(2001) - et al.
Digestion patterns of endogenous and different exogenous proteins affect the composition of intestinal effluents in humans
J Nutr
(1995) - et al.
Net postprandial utilization of [15N]-labeled milk protein nitrogen is influenced by diet composition in humans
J Nutr
(1999) - et al.
Nutritional value of [15N]-soy protein isolate assessed from ileal digestibility and postprandial protein utilization in humans
J Nutr
(1999)
The 15N amino acid dilution method allows the determination of the real digestibility and of the ileal endogenous losses of the respective amino acid in pigs
J Nutr
[15N]-labeled pea flour protein nitrogen exhibits good ileal digestibility and postprandial retention in humans
J Nutr
Nitrogen and amino acid requirements: the Massachusetts Institute of Technology amino acid requirement pattern
J Nutr
A high-protein meal exceeds anabolic and catabolic capacities in rats adapted to a normal protein diet
J Nutr
Gastrojejunal kinetics and the digestion of [15N]beta-lactoglobulin and casein in humans: the influence of the nature and quantity of the protein
Am J Clin Nutr
Feeding diets containing high levels of milk products or cellulose decrease urease activity and ammonia production in rat intestine
J Nutr
The current 15N-leucine infusion technique is not suitable for quantitative measurements of ileal endogenous amino acid flows in pigs
J Nutr
Incorporation of urea and ammonia nitrogen into ileal and fecal microbial proteins and plasma free amino acids in normal men and ileostomates
Am J Clin Nutr
Dietary amino acids are the preferential source of hepatic protein synthesis in piglets
J Nutr
Catabolism dominates the first-pass intestinal metabolism of dietary essential amino acids in milk protein-fed piglets
J Nutr
Infusion of soy and casein protein meals affects interorgan amino acid metabolism and urea kinetics differently in pigs
J Nutr
Human adult amino acid requirements: [1-13C]leucine balance evaluation of the efficiency of utilization and apparent requirements for wheat protein and lysine compared with those for milk protein in healthy adults
Am J Clin Nutr
Dispensable and indispensable amino acids for humans
J Nutr
A theoretical basis for increasing current estimates of the amino acid requirements in adult man, with experimental support
Am J Clin Nutr
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Address requests for reprints to: Claire Gaudichon, Ph.D., Institut National Agronomique Paris-Grignon (INA PG), Unité de Physiologie de la Nutrition et du Comportement Alimentaire, 16 Rue Claude Bernard, 75005 Paris, France. e-mail: [email protected] ; fax: (33) 1-44-08-18-25.
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Supported by grants from ARILAIT Recherches (Paris, France), PROCOPE grants from the Deutsche Akademische Austauschdienst (Bonn, Germany), and the French Ministry for Foreign Affairs (Paris, France).
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Dr. Metges is currently affiliated with the Research Institute for the Biology of Farm Animals, Dummerstorf, Germany.