Gastro-jejunal digestion of soya-bean-milk protein in humans.
In order to determine how soya-bean proteins are digested and metabolized in the human intestine before colonic bacterial fermentation and to estimate their true digestibility, the gastro-jejunal behaviour of soya-bean proteins in water and in two other forms (a concentrated soya-bean-protein solution (isolate) and a drink composed of crude soya-bean proteins (soymilk)) was studied in humans. Experiments were carried out in eight healthy volunteers using a double-lumen steady-state intestinal perfusion method with polyethyleneglycol (PEG) as a non-absorbable volume marker. Gastric emptying and N and electrolyte contents of the jejunal digesta were analysed. Gastric half-emptying time (min) of the liquid phase after water ingestion (12.59 (SE 0.12)) was shorter (P < 0.05) than those for soymilk (37.74 (SE 11.57)) and isolate (36.52 (SE 11.23)). Electrolytic balances showed that for all meals, Na+, Cl- and K+ were secreted when Ca2+ was efficiently absorbed from the jejunal lumen. Gastro-jejunal N absorption for isolate and soymilk were 63 and 49% respectively, and were not significantly different from one another; after water ingestion, endogenous N was estimated to be 21 mmol. An estimate of the exogenous:endogenous values for the effluents was obtained from the amino acid compositions of soymilk and effluents after water or soymilk ingestion, indicating that 70% of the total N was exogenous and 30% endogenous. Under these conditions the endogenous fraction represented 31 mmol after soymilk ingestion and the gastro-jejunal N balance indicated that 54% of the soymilk was absorbed. This finding indicates that the true gastrojejunal digestibility of soya-bean proteins is similar to that of milk proteins.
Baglieri
A
A
Institut National de la Recherche Agronomique, Unité de Nutrition Humaine et de Physiologie Intestinale, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France.
Mahe
S
S
Zidi
S
S
Huneau
J F
JF
Thuillier
F
F
Marteau
P
P
Tome
D
D
D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion / Q000502:physiology*; D004386:Duodenum / Q000378:metabolism*; D005260:Female; D005746:Gastric Emptying; D005753:Gastric Mucosa / Q000378:metabolism*; D005772:Gastrointestinal Transit; D006801:Humans; D009584:Nitrogen / Q000378:metabolism; D010477:Perfusion; D014674:Plant Proteins, Dietary / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D030262:Soybean Proteins; D013025:Glycine max / Q000378:metabolism*
D000596:Amino Acids; D002712:Chlorides; D004044:Dietary Proteins; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins; D012964:Sodium; D009584:Nitrogen; D011188:Potassium; D002118:Calcium