Leucine co-ingestion improves post-prandial muscle protein accretion in elderly men

Benjamin T. Wall, Henrike M. Hamer, A. de Lange, A. Kiskini, Bart B.L. Groen, Joan M.G. Senden, Annemie P. Gijsen, Lex B. Verdijk, Luc J.C. van Loon

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Abstract

Background & aims: It has been speculated that the amount of leucine in a meal largely determines the post-prandial muscle protein synthetic response to food intake. The present study investigates the impact of leucine co-ingestion on subsequent post-prandial muscle protein accretion following the ingestion of a single bolus of dietary protein in elderly males.

Methods: Twenty-four elderly men (74.3 +/- 1.0 y) were randomly assigned to ingest 20 g intrinsically L-[1-C-13]phenylalanine-labeled casein protein with (PRO + LEU) or without (PRO) 2.5 g crystalline leucine. Ingestion of specifically produced intrinsically labeled protein allowed us to create a plasma phenylalanine enrichment pattern similar to the absorption pattern of phenylalanine from the ingested protein and assess the subsequent post-prandial incorporation of L-[1-C-13] phenylalanine into muscle protein.

Results: Plasma amino acid concentrations increased rapidly following protein ingestion in both groups, with higher leucine concentrations observed in the PRO + LEU compared with the PRO group (P <0.01). Plasma L-[1-C-13]phenylalanine enrichments increased rapidly and to a similar extent in both groups following protein ingestion. Muscle protein-bound L-[1-C-13]phenylalanine enrichments were significantly greater after PRO + LEU when compared with PRO at 2 h (72%; 0.0078 +/- 0.0010 vs. 0.0046 +/- 0.00100 MPE, respectively; P <0.05) and 6 h (25%; 0.0232 +/- 0.0015 vs. 0.0185 +/- 0.0010 MPE, respectively; P <0.05) following protein ingestion. The latter translated into a greater muscle protein synthetic rate following PRO + LEU compared with PRO over the entire 6 h post-prandial period (22%; 0.049 +/- 0.003 vs. 0.040 +/- 0.003% h(-1), respectively; P <0.05).

Conclusion: Leucine co-ingestion with a bolus of pure dietary protein further stimulates post-prandial muscle protein synthesis rates in elderly men. 

Original languageEnglish
Pages (from-to)412-419
Number of pages8
JournalClinical Nutrition
Volume32
Issue number3
DOIs
Publication statusPublished - Jun 2013

Keywords

  • Skeletal muscle
  • Aging
  • Sarcopenia
  • Amino acids
  • Anabolic resistance
  • INTRINSICALLY LABELED MILK
  • HUMAN-NUTRITION RESEARCH
  • AMINO-ACID-METABOLISM
  • HUMAN SKELETAL-MUSCLE
  • TYPE-2 DIABETIC MEN
  • BETA-CELL FUNCTION
  • BED-REST
  • INSULIN
  • BODY
  • SUPPLEMENTATION

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