title: Compared with Raw Bovine Meat, Boiling but Not Grilling, Barbecuing, or Roasting Decreases Protein Digestibility without Any Major Consequences for Intestinal Mucosa in Rats, although the Daily Ingestion of Bovine Meat Induces Histologic Modifications in the Colon.
abstract: Cooking may impair meat protein digestibility. When undigested proteins are fermented by the colon microbiota, they can generate compounds that potentially are harmful to the mucosa.
  
  
  
  This study addressed the effects of typical cooking processes and the amount of bovine meat intake on the quantity of undigested proteins entering the colon, as well as their effects on the intestinal mucosa.
  
  
  
  Male Wistar rats (n = 88) aged 8 wk were fed 11 different diets containing protein as 20% of energy. In 10 diets, bovine meat proteins represented 5% [low-meat diet (LMD)] or 15% [high-meat diet (HMD)] of energy, with the rest as total milk proteins. Meat was raw or cooked according to 4 processes (boiled, barbecued, grilled, or roasted). A meat-free diet contained only milk proteins. After 3 wk, rats ingested a (15)N-labeled meat meal and were killed 6 h later after receiving a (13)C-valine injection. Meat protein digestibility was determined from (15)N enrichments in intestinal contents. Cecal short- and branched-chain fatty acids and hydrogen sulfide were measured. Intestinal tissues were used for the assessment of protein synthesis rates, inflammation, and histopathology.
  
  
  
  Meat protein digestibility was lower in rats fed boiled meat (94.5% ± 0.281%) than in the other 4 groups (97.5% ± 0.0581%, P < 0.001). Cecal and colonic bacterial metabolites, inflammation indicators, and protein synthesis rates were not affected by cooking processes. The meat protein amount had a significant effect on cecal protein synthesis rates (LMD > HMD) and on myeloperoxidase activity in the proximal colon (HMD > LMD), but not on other outcomes. The ingestion of bovine meat, whatever the cooking process and the intake amount, resulted in discrete histologic modifications of the colon (epithelium abrasion, excessive mucus secretion, and inflammation).
  
  
  
  Boiling bovine meat at a high temperature (100°C) for a long time (3 h) moderately lowered protein digestibility compared with raw meat and other cooking processes, but did not affect cecal bacterial metabolites related to protein fermentation. The daily ingestion of raw or cooked bovine meat had no marked effect on intestinal tissues, despite some slight histologic modifications on distal colon.
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Marion
authors.initials: M
authors.lastname: Oberli
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Annaïg
authors.initials: A
authors.lastname: Lan
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Nadezda
authors.initials: N
authors.lastname: Khodorova
authors.affiliation: INRA, UR370 Qualité des Produits Animaux, Saint Genès Champanelle, France; and.
authors.forename: Véronique
authors.initials: V
authors.lastname: Santé-Lhoutellier
authors.affiliation: Service d'Anatomie et Cytologie Pathologique, Hôpital Xavier Bichat, Paris, France.
authors.forename: Francine
authors.initials: F
authors.lastname: Walker
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Julien
authors.initials: J
authors.lastname: Piedcoq
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Davila
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: François
authors.initials: F
authors.lastname: Blachier
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Daniel
authors.initials: D
authors.lastname: Tomé
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France;
authors.forename: Gilles
authors.initials: G
authors.lastname: Fromentin
authors.affiliation: UMR Physiologie de la Nutrition et du Comportement Alimentaire, AgroParisTech, INRA, Université Paris Saclay, Paris, France; claire.gaudichon@agroparistech.fr.
authors.forename: Claire
authors.initials: C
authors.lastname: Gaudichon
mesh_terms: D000818:Animals; D002417:Cattle; D002432:Cecum / Q000378:metabolism / Q000382:microbiology; D003106:Colon / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D003296:Cooking / Q000379:methods*; D004032:Diet; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005247:Feeding Behavior; D005285:Fermentation; D007249:Inflammation / Q000209:etiology / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D008297:Male; D009195:Peroxidase / Q000378:metabolism; D014176:Protein Biosynthesis; D017208:Rats, Wistar; D000069466:Red Meat
chemical_list: D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D009195:Peroxidase
keywords: colon fermentation; colon mucosa; cooked meat; protein digestion; stable isotopes