Dietary peptides increase endogenous amino acid losses from the gut in adults.
BACKGROUND
Accurate estimates of endogenous ileal total nitrogen and amino acid flows are necessary to ascertain true dietary amino acid digestibility coefficients and for the factorial estimation of dietary amino acid requirements.


OBJECTIVE
The objective was to ascertain endogenous amino acid losses from the small bowel in human subjects consuming a protein-free diet or a diet with enzyme-hydrolyzed casein (EHC; MW <5000) as the sole source of nitrogen.


METHODS
The subjects were 8 men and women with terminal ileum ileostomies after ulcerative colitis who consumed the protein-free and EHC-based diets in a crossover design. Each subject received each test diet in single meals followed by 2 consecutive 9-h total collections of digesta. Digesta samples for the EHC treatment were centrifuged and ultrafiltered (10 000 MW cutoff), with the precipitate-plus-retentate fraction (>10 000 MW) providing a measurement of endogenous ileal amino acids.


RESULTS
The mean endogenous flows for most of the amino acids and nitrogen were significantly (P < 0.05) higher when determined with the EHC-based diet than with the protein-free diet. Mean (n = 8) endogenous ileal nitrogen flows were 2061 and 4233 mug/g dry matter intake for the protein-free and EHC-based diets, respectively.


CONCLUSIONS
The traditional protein-free method underestimates endogenous ileal amino acid loss in adults.
Moughan
Paul J
PJ
Riddet Centre, Massey University, Palmerston North, New Zealand. p.j.moughan@massey.ac.nz
Butts
Christine A
CA
Rowan
Angela M
AM
Deglaire
Amélie
A
D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism*; D002364:Caseins / Q000008:administration & dosage / Q000378:metabolism*; D018592:Cross-Over Studies; D018753:Diet, Protein-Restricted; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D004063:Digestion; D005260:Female; D006801:Humans; D007081:Ileostomy; D007082:Ileum / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000008:administration & dosage / Q000378:metabolism; D009751:Nutritional Requirements
D000596:Amino Acids; D002364:Caseins; D004044:Dietary Proteins; C475729:casein hydrolysate; D009584:Nitrogen