Gut luminal endogenous protein: Implications for the determination of ileal amino acid digestibility in humans

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dc.citation.issueSupplement S2
dc.citation.volume108
dc.contributor.authorMoughan PJ
dc.contributor.authorRutherfurd S
dc.date.available2012
dc.date.issued2012
dc.description.abstractThe true ileal digestibility assay provides the most informative measure of digestibility to assess bioavailability of amino acids in foods for humans. To determine ‘true’ estimates of ileal amino acid digestibility, requires that endogenous amino acids present in digesta at the terminal ileum be quantified. The amounts of endogenous amino acids in ileal digesta can be determined after feeding an animal or human a protein-free diet (traditional approach) or by various methods after giving a protein-containing diet. When the protein-free method has been applied with adult human subjects an overall mean value (three separate studies) for endogenous ileal nitrogen flow of 800 mg N/d has been reported. This value is considerably lower than a comparable value obtained after feeding protein of 1852 mg N/d (mean of four separate studies), and thus endogenous ileal N and amino acids should be measured under conditions of protein alimentation. There is some confusion concerning the terminology used to define digestibility, with the term “true” digestibility having different adopted meanings. Here, true amino acid digestibility is defined as apparent amino acid digestibility corrected for the basal amino acid losses determined after giving either a protein-free or a protein-containing diet. Basal losses should be determined at a defined dry-matter and protein intake. The protein-free diet approach to determining endogenous amino acids is considered unphysiological and basal losses refer to ileal endogenous amino acid flows associated with digesta dry-matter flow, and not including “specific” effects of dietary factors such as non starch polysaccharides and anti nutritional factors. Arguments are advanced that the enzyme hydrolysed protein/ultra filtration method may be suitable for routine application with a cannulated pig model, to obtain physiologically-valid basal estimates of ileal endogenous amino acids to allow calculation of true ileal amino acid digestibility in the pig, and then prediction (via statistical relationships) of true coefficients of amino acid digestibility in humans.
dc.description.confidentialFALSE
dc.description.publication-statusPublished
dc.format.extentS258 - S263
dc.identifier.citationBritish Journal of Nutrition, 2012, 108 (Supplement S2), pp. S258 - S263
dc.identifier.doi10.1017/S0007114512002474
dc.identifier.eissn1475-2662
dc.identifier.elements-id190865
dc.identifier.harvestedMassey_Dark
dc.identifier.issn0007-1145
dc.identifier.urihttps://hdl.handle.net/10179/13264
dc.publisherCambridge University Press
dc.relation.isPartOfBritish Journal of Nutrition
dc.subjectIleal digestibility
dc.subjectHuman
dc.subjectProtein
dc.subjectAmino Acids
dc.subjectEndogenous protein
dc.subject.anzsrc0702 Animal Production
dc.subject.anzsrc0908 Food Sciences
dc.subject.anzsrc1111 Nutrition and Dietetics
dc.titleGut luminal endogenous protein: Implications for the determination of ileal amino acid digestibility in humans
dc.typeJournal article
pubs.notesNot known
pubs.organisational-group/Massey University
pubs.organisational-group/Massey University/College of Health
pubs.organisational-group/Massey University/Other
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