Nutritional value of [15N]-soy protein isolate assessed from ileal digestibility and postprandial protein utilization in humans.
The purpose of this work was to assess the true oro-ileal digestibility, and to concurrently quantify the deamination of absorbed dietary nitrogen to examine the postprandial nutritional value of a soy protein isolate (SPI) in humans. To assess bioavailability and bioutilization of SPI, 10 healthy volunteers ingested 30 g of SPI, intrinsically and uniformly [15N]-labeled, added with 100 g of sucrose and water up to a final volume of 500 mL. True ileal digestibility was assessed by the [15N]-dilution method for 8 h by means of a naso-intestinal intubation technique. To describe and quantify exogenous nitrogen deamination for the same time period, urine and plasma samples were collected. True oro-ileal digestibility of SPI nitrogen was 91%. The amount of absorbed SPI amino acids used for nonoxidative disposal, i.e., postprandial biological value, was 86% 8 h after meal ingestion. Hence, net postprandial protein utilization of SPI was 78%. Compared to previous data that were assessed under the same condition in humans, the nutritional value of SPI is 92% of that in milk protein concentrate.
Mariotti
F
F
Institut National de la Recherche Agronomique, Unité de Nutrition Humaine et de Physiologie Intestinale, Institut National Agronomique Paris-Grignon, 75231 Paris Cédex 05, France.
Mahé
S
S
Benamouzig
R
R
Luengo
C
C
Daré
S
S
Gaudichon
C
C
Tomé
D
D
D000328:Adult; D001682:Biological Availability; D004044:Dietary Proteins / Q000378:metabolism*; D004435:Eating / Q000502:physiology; D005260:Female; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D009753:Nutritive Value; D019518:Postprandial Period; D030262:Soybean Proteins / Q000493:pharmacokinetics*
D004044:Dietary Proteins; D030262:Soybean Proteins; D009584:Nitrogen