New stable isotope method to measure protein digestibility and response to pancreatic enzyme intake in cystic fibrosis

• Published in: Clinical nutrition (Edinburgh, Scotland) Vol. 33; no. 6; pp. 1024 - 1032
• Main Authors: Engelen, M.P.K.J., Com, G., Anderson, P.J., Deutz, N.E.P.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Adolescent; Adult; adults; Bacterial Proteins - administration & dosage; Bacterial Proteins - pharmacokinetics; Biological and medical sciences; blood sampling; Body Composition; Case-Control Studies; Child; children; citrulline; Citrulline - blood; Cystic fibrosis; Cystic Fibrosis - physiopathology; Dietary Proteins - administration & dosage; Dietary Proteins - pharmacokinetics; Dietary Supplements; digestibility; digestible protein; digestion; Dose-Response Relationship, Drug; enzymes; Errors of metabolism; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Gastroenterology and Hepatology; Gastrointestinal Tract - drug effects; Gastrointestinal Tract - metabolism; Healthy Volunteers; Humans; Isotope Labeling - methods; Male; Medical sciences; Metabolic diseases; Miscellaneous hereditary metabolic disorders; muscles; Muscular Atrophy - prevention & control; nitrogen; Novel stable isotope method; Pancreas - drug effects; Pancreas - enzymology; Pancreatic enzymes; patients; phenylalanine; Protein digestibility; protein intake; Radioisotopes - analysis; Spirulina; stable isotopes; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Whole-body citrulline production; Young Adult; Cystic fibrosis; Protein digestibility; Novel stable isotope method; Whole-body citrulline production; Pancreatic enzymes; Consumption; Respiratory disease; Enzyme; Digestive diseases; Metabolic diseases; Pancreas; Isotopes; Protein; Genetic disease; Pancreatic disease
• ISSN: 0261-5614; 1532-1983; 1532-1983
• DOI: 10.1016/j.clnu.2013.11.004

Adequate protein intake and digestion are necessary to prevent muscle wasting in cystic fibrosis (CF). Accurate and easy-to-use methodology to quantify protein maldigestion is lacking in CF. To measure protein digestibility and the response to pancreatic enzyme intake in CF by using a new stable isotope methodology. In 19 CF and 8 healthy subjects, protein digestibility was quantified during continuous (sip) feeding for 6 h by adding 15N-labeled spirulina protein and L-[ring-2H5]phenylalanine (PHE) to the nutrition and measuring plasma ratio [15N]PHE to [2H5]PHE. Pancreatic enzymes were ingested after 2 h in CF and the response in protein digestibility was assessed. To exclude difference in mucosal function, postabsorptive whole-body citrulline (CIT) production rate was measured by L-[5-13C-5,5-2H2]-CIT pulse and blood samples were taken to analyze tracer-tracee ratios. Protein digestibility was severely reduced in the CF group (47% of healthy subjects; P < 0.001). Intake of pancreatic enzymes induced a slow increase in protein digestibility in CF until 90% of values obtained by healthy subjects. Maximal digestibility was reached at 100 min and maintained for 80 min. Stratification into CF children (n = 10) and adults showed comparable values for protein digestibility and similar kinetic responses to pancreatic enzyme intake. Whole-body citrulline production was elevated in CF indicating preserved mucosal function. Protein digestibility is severely compromised in patients with CF as measured by this novel and easy-to-use stable isotope approach. Pancreatic enzymes are able to normalize protein digestibility in CF, albeit with a severe delay. Registration ClinicalTrials.gov = NCT01494909.