Postprandial metabolic utilization of wheat protein in humans.
BACKGROUND
The quality of cereal protein has been little studied in humans despite its quantitative importance in the diet, particularly in developing countries.


OBJECTIVE
The objective of this study was to determine the nutritional value of wheat protein in humans as assessed by the measurement of their real ileal digestibility and postprandial retention.


METHODS
Healthy young adults (n = 14) were fitted with an intestinal tube to allow the collection of intestinal fluid in the duodenum or terminal ileum. Subjects received a mixed meal of 136 g wheat toast that contained 24.6 g uniformly and intrinsically [(15)N]-labeled wheat protein. Intestinal fluid, blood, and urine were collected for 8 h postprandially.


RESULTS
The real ileal digestibility of dietary wheat nitrogen amounted to 90.3 +/- 4.3%. The cumulative amount of dietary nitrogen transferred to the deamination pools reached a plateau at 8 h of 24.7 +/- 6.8% of the amount ingested. The urinary excretion of dietary nitrogen in ammonia was high (0.8 +/- 0.3% of ingested dose). The incorporation of dietary nitrogen into serum protein reached 7.0 +/- 1.9% of the meal. Postprandial wheat protein retention was 66.1 +/- 5.8%.


CONCLUSIONS
Our results show that wheat proteins had the same true ileal digestibility as did most of the plant proteins already studied in humans, but also that they had a lower postprandial nitrogen retention value. However, this low value was higher than that predicted from the calculation of indispensable amino acid scores, ie, 89% rather than 30-40% of the nutritional value of milk proteins.
Bos
Cécile
C
Department of Nutrition Physiology and Feeding Control, Institut National de la Recherche Agronomique-Institut National Agronomique, Paris-Grignon, and the Department of Gastroenterology, Avicenne Hospital, Bobigny, France. bos@inapg.inra.fr
Juillet
Barbara
B
Fouillet
Hélène
H
Turlan
Lucie
L
Daré
Sophie
S
Luengo
Catherine
C
N'tounda
Rufin
R
Benamouzig
Robert
R
Gausserès
Nicolas
N
Tomé
Daniel
D
Gaudichon
Claire
C
D000328:Adult; D001682:Biological Availability; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D002523:Edible Grain; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D019518:Postprandial Period; D014508:Urea / Q000378:metabolism*
D004044:Dietary Proteins; D014508:Urea; D009584:Nitrogen