Endogenous proteins in the ileal digesta of adult humans given casein-, enzyme-hydrolyzed casein- or crystalline amino-acid-based diets in an acute feeding study

• Published in: European journal of clinical nutrition Vol. 68; no. 3; pp. 363 - 369
• Main Authors: Miner-Williams, W, Deglaire, A, Benamouzig, R, Fuller, M F, Tomé, D, Moughan, P J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.03.2014; Nature Publishing Group
• Subjects: 631/443; 692/698/2741; 692/700/2814; Adult; Amino acids; Amino Acids - administration & dosage; Amino Acids - pharmacokinetics; Biological and medical sciences; Casein; Caseins - administration & dosage; Caseins - chemistry; Caseins - pharmacokinetics; Clinical Nutrition; Crystal structure; Crystallinity; Diet; Dietary Proteins - administration & dosage; Dietary Proteins - pharmacokinetics; Digestion; Digestive tract; Enzymes; Epidemiology; Feeding. Feeding behavior; Female; Food and Nutrition; Food consumption; Fundamental and applied biological sciences. Psychology; Health aspects; Human health and pathology; Humans; Ileum; Ileum - drug effects; Ileum - metabolism; Internal Medicine; Intestine; Life Sciences; Male; Meals; Medical research; Medical sciences; Medicine; Medicine & Public Health; Medicine, Experimental; Membrane proteins; Metabolic Diseases; Microbiology and Parasitology; Mucin; Nitrogen; original-article; Peptides; Proteins; Public Health; Reabsorption; Small intestine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; France; naso-ileal tube; casein; endogenous protein; terminal ileum; enzyme-hydrolyzed casein; acute feeding; Human; Digestive system; Enzyme; Acute; Metabolic diseases; Small intestine; Ileum; Protein; Feeding; Endogenous; Casein; Diet; Aminoacid; Adult; digestion; peptide; caséine; intestin; hydrolyse; santé humaine
• ISSN: 0954-3007; 1476-5640
• DOI: 10.1038/ejcn.2013.270

Background/Objectives: To ascertain if the form of dietary nitrogen (free amino acids (AA), small peptides, or intact protein) affects the endogenous nitrogen containing substances lost from the upper digestive tract of humans. Subjects/Methods: Digesta were collected via a naso-ileal tube from the terminal ileum of 16 adult humans in a single parallel study following an acute feeding regimen. Subjects were given an iso-nitrogenous and isocaloric test meal containing 150 g of casein (CAS) ( n= 6), enzyme-hydrolyzed casein (HCAS) ( n= 5) or crystalline AA ( n= 5) dissolved in 550 ml of water, as the sole sources of nitrogen. Results: The mean concentrations and flows of total nitrogen, protein nitrogen, and soluble protein nitrogen passing the terminal ileum were significantly higher ( P <0.01) for the CAS and HCAS test-meal groups compared to the AA meal group. Dietary CAS and HCAS had a considerable influence on digesta mucin concentrations and flows compared to free AA (+41%). Only 3–4% of the total nitrogen remained unidentified. Conclusions: The form of dietary nitrogen (protein, small peptides or free AA) had an acute effect upon the secretion or reabsorption of endogenous proteins in the small intestine of healthy humans, as evident from significant differences in both the quantity and composition of the proteins found in digesta at the end of the ileum.