Exogenous and endogenous nitrogen flow rates and level of protein hydrolysis in the human jejunum after [15N]milk and [15N]yoghurt ingestion.
Milk and yoghurt proteins were 15N-labelled in order to measure the flow rate of exogenous N during digestion in the human intestine. After fasting overnight, sixteen healthy volunteers, each with a naso-jejunal tube, ingested either [15N]milk (n 7) or [15N]yoghurt (n 9). Jejunal samples were collected every 20 min for 4 h. A significant stimulation of endogenous N secretion was observed during the 20-60 min period after yoghurt ingestion and the 20-40 min period after milk ingestion. The endogenous N flows over a 4 h period did not differ between the groups (44.3(SEM 6.5) mmol for milk and 63.5(SEM 5.9) mmol for yoghurt). The flow rates of exogenous N indicated a delayed gastric emptying of the yoghurt N compared with N from milk. The jejunal non-protein N (NPN) flow rate increased significantly after milk and yoghurt ingestion due to an increase in the exogenous NPN flow rate. The NPN fraction of exogenous N ranged between 40 and 80%. The net gastro-jejunal absorption of exogenous N did not differ significantly between milk (56.7(SEM 8.5)%) and yoghurt (50.9(SEM 7)%). The high level of exogenous N hydrolysis is in accordance with the good digestibility of milk products. Fermentation modifies only the gastric emptying rate of N and does not affect the level of diet hydrolysis, the endogenous N stimulation or the digestibility rate.
Gaudichon
C
C
Unité INRA de Nutrition Humaine et de Physiologie Intestinale, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France.
Mahé
S
S
Roos
N
N
Benamouzig
R
R
Luengo
C
C
Huneau
J F
JF
Sick
H
H
Bouley
C
C
Rautureau
J
J
Tome
D
D
D000328:Adult; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion / Q000502:physiology*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007408:Intestinal Absorption / Q000502:physiology; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D008894:Milk Proteins / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism* / Q000493:pharmacokinetics; D015014:Yogurt
D004044:Dietary Proteins; D008894:Milk Proteins; D009584:Nitrogen