15N-labeled immunoglobulins from bovine colostrum are partially resistant to digestion in human intestine.
To evaluate true ileal digestibility of bovine immunoglobulins, seven healthy human adults ingested a 15N-labeled preparation of an immunoglobulin concentrate. After fasting overnight, subjects drank 400 mL of immunoglobulin concentrate (77 mmol), and ileal effluents were collected for 8 h at 20-min intervals using a naso-intestinal intubation technique. In addition to osmolality and pH, the concentrations of exogenous and endogenous nitrogen and ions (Na+, K+, Cl-, Ca2+, Mg2+) in the effluents were measured. Bovine immunoglobulin concentrations (IgG, IgM, IgA) were estimated by a radial immunodiffusion technique. The mean flow rate of the liquid phase was 22.3 +/- 6.1 mL/20 min and did not vary significantly during the collection period. No change was observed for osmolality, pH or Na+, K+ and Cl- concentrations. Two hours after meal ingestion, Ca2+ and Mg2+ concentrations increased significantly (P < 0.05). The recoveries of nitrogen of ingested IgG and IgM still immunologically active were 19 +/- 3% and 19 +/- 4%, respectively. No IgA was detected in the ileum. Mean digestibility of the exogenous nitrogen fraction was 79 +/- 3%. In comparison to literature data, which show that other milk proteins have ileal digestibilities of > 90%, our results demonstrate a lower ileal digestibility of bovine immunoglobulins in humans.
Roos
N
N
Institut für Physiologie und Biochemie der Ernährung, Kiel, Germany.
Mahé
S
S
Benamouzig
R
R
Sick
H
H
Rautureau
J
J
Tomé
D
D
D000328:Adult; D000818:Animals; D002118:Calcium / Q000032:analysis; D002417:Cattle; D002712:Chlorides / Q000032:analysis; D002850:Chromatography, Gel; D003126:Colostrum / Q000276:immunology*; D004063:Digestion; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007082:Ileum / Q000378:metabolism*; D007070:Immunoglobulin A / Q000032:analysis / Q000378:metabolism; D007074:Immunoglobulin G / Q000032:analysis / Q000378:metabolism; D007075:Immunoglobulin M / Q000032:analysis / Q000378:metabolism; D007136:Immunoglobulins / Q000032:analysis* / Q000378:metabolism* / Q000494:pharmacology; D007441:Intubation, Gastrointestinal; D008274:Magnesium / Q000032:analysis; D008297:Male; D009587:Nitrogen Isotopes; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis
D002712:Chlorides; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins; D009587:Nitrogen Isotopes; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium