The gastro-ileal digestion of 15N-labelled pea nitrogen in adult humans.

The aim of the present study was to determine the gastro-ileal behaviour of pea protein in humans. For this purpose, twelve healthy volunteers were intubated with an intestinal tube located either in the jejunum (n 5) or in the ileum (n 7). After fasting overnight, they ingested 195 mmol N of [15N]pea. Intestinal samples were collected for 6 h in the jejunum and for 8 h in the ileum. Before meal ingestion the basal liquid flow rate (ml/min) was 2.01 (SD 0.31) in the jejunum and 2.02 (SD 0.33) in the ileum. After meal ingestion the liquid phase of the meal peaked in the 40-60 min period in the jejunum and in the 150-180 min period in the ileum. The jejuno-ileal transit time of the liquid phase of the meal was 102 min. The basal flow rate of endogenous N (mmol N/min) was 0.22 (SD 0.15) in the jejunum and 0.16 (SD 0.10) in the ileum. The endogenous N flow rate peaked significantly (P < 0.05) in the jejunum in the 40-60 min period whereas no stimulation of endogenous N could be detected in the ileum after meal ingestion. A significantly increased (P < 0.05) concentration of exogenous N was detected in the jejunum during the 20-320 min period and during the 90-480 min period in the ileum. The overall true gastro-ileal absorption of pea N was 89.4 (SD 1.1)% with 69 (SD 14)% absorbed between the stomach and the proximal jejunum and 20.4% between the proximal jejunum and the terminal ileum. The percentage of ethanol-insoluble fraction (PN) in the exogenous N at the terminal ileum increased significantly (P < 0.05) to 75% after 360 min. These results suggest that heat-treated pea protein has a digestibility close to that of animal protein.