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Dietary protein quality influences the pattern of natural isotopic composition of nitrogen in rats
Author(s) -
Poupin Nathalie,
Fouillet Hélène,
Mariotti François,
Tomé Daniel,
Huneau JeanFrançois,
Bos Cécile
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.740.6
Subject(s) - splanchnic , protein quality , composition (language) , dietary protein , biological value , metabolism , endocrinology , biology , medicine , protein metabolism , kidney , chemistry , biochemistry , blood flow , linguistics , philosophy
The natural 15 N enrichment (δ 15 N) in some specific tissues (blood, hair) has been shown to vary with diet quality. In this work, we investigated the influence of two dietary protein sources of different quality (milk and soy) on the δ 15 N values in various tissues. Male Wistar rats (n=18) were fed for 3 weeks experimental diets differing only in their protein source (soy or milk). δ 15 N values were determined in both protein and non‐protein fractions of blood and peripheral (muscle, kidney, skin) and splanchnic (liver, intestine) organs. Results were expressed as diet‐tissue discrimination (Δ 15 N = δ 15 N tissue − δ 15 N diet ). Regardless of the diet, the protein fraction of tissues was always enriched in 15 N relative to the non‐protein fraction and relative to the diets (Δ 15 N>0). Δ 15 N of protein fractions differed among tissues and were also influenced by the protein source. They were indeed higher in rats fed with soy (vs. milk) diet, in all tissues but the intestine (see Fig.). We conclude that Δ 15 N is lower when dietary protein quality is higher. Furthermore, the amplitude of Δ 15 N differences between diets varied among tissues (being for instance 3‐fold higher in skin than in liver), indicating that the nature of the dietary protein source differentially impacts the metabolism of splanchnic and peripheral tissues. We propose that Δ 15 N is a sensitive marker of protein biological value and regional protein metabolism.