title: Minced beef is more rapidly digested and absorbed than beef steak, resulting in greater postprandial protein retention in older men.
abstract: BACKGROUND
  Older individuals generally experience a reduced food-chewing efficiency. As a consequence, food texture may represent an important factor that modulates dietary protein digestion and absorption kinetics and the subsequent postprandial protein balance.
  
  
  OBJECTIVE
  We assessed the effect of meat texture on the dietary protein digestion rate, amino acid availability, and subsequent postprandial protein balance in vivo in older men.
  
  
  METHODS
  Ten older men (mean ± SEM age: 74 ± 2 y) were randomly assigned to a crossover experiment that involved 2 treatments in which they consumed 135 g of specifically produced intrinsically L-[1-(13)C]phenylalanine-labeled beef, which was provided as beef steak or minced beef. Meat consumption was combined with continuous intravenous L-[ring-(2)H5]phenylalanine and L-[ring-(2)H2]tyrosine infusion to assess beef protein digestion and absorption kinetics as well as whole-body protein balance and skeletal muscle protein synthesis rates.
  
  
  RESULTS
  Meat protein-derived phenylalanine appeared more rapidly in the circulation after minced beef than after beef steak consumption (P < 0.05). Also, its availability in the circulation during the 6-h postprandial period was greater after minced beef than after beef steak consumption (61 ± 3% compared with 49 ± 3%, respectively; P < 0.01). The whole-body protein balance was more positive after minced beef than after beef steak consumption (29 ± 2 compared with 19 ± 3 μmol phenylalanine/kg, respectively; P < 0.01). Skeletal muscle protein synthesis rates did not differ between treatments when assessed over a 6-h postprandial period.
  
  
  CONCLUSIONS
  Minced beef is more rapidly digested and absorbed than beef steak, which results in increased amino acid availability and greater postprandial protein retention. However, this does not result in greater postprandial muscle protein synthesis rates. This trial was registered at clinicaltrials.gov as NCT01145131.
authors: Top Institute Food & Nutrition, Wageningen, The Netherlands.
authors: Bart
authors: B
authors: Pennings
authors: Bart B L
authors: BB
authors: Groen
authors: Jan-Willem
authors: JW
authors: van Dijk
authors: Anneke
authors: A
authors: de Lange
authors: Alexandra
authors: A
authors: Kiskini
authors: Marjan
authors: M
authors: Kuklinski
authors: Joan M G
authors: JM
authors: Senden
authors: Luc J C
authors: LJ
authors: van Loon
mesh_terms: D000368:Aged; D000818:Animals; D001682:Biological Availability; D001786:Blood Glucose / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis; D002417:Cattle; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004063:Digestion / Q000502:physiology*; D006801:Humans; D008297:Male; D008460:Meat; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010649:Phenylalanine / Q000493:pharmacokinetics; D019518:Postprandial Period; D011795:Surveys and Questionnaires; D014443:Tyrosine / Q000008:administration & dosage
chemical_list: D001786:Blood Glucose; D002247:Carbon Isotopes; D004044:Dietary Proteins; D009124:Muscle Proteins; D014443:Tyrosine; D010649:Phenylalanine