PMID- 16960178
OWN - NLM
STAT- MEDLINE
DCOM- 20061010
LR  - 20230318
IS  - 0002-9165 (Print)
IS  - 0002-9165 (Linking)
VI  - 84
IP  - 3
DP  - 2006 Sep
TI  - Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to 
      the same extent in young and elderly lean men.
PG  - 623-32
AB  - BACKGROUND: The progressive loss of skeletal muscle mass with aging is attributed 
      to a disruption in the regulation of skeletal muscle protein turnover. OBJECTIVE: 
      We investigated the effects on whole-body protein balance and mixed-muscle 
      protein synthesis rates of the ingestion of carbohydrate with or without protein 
      and free leucine after simulated activities of daily living. DESIGN: Eight 
      elderly (75 +/- 1 y) and 8 young (20 +/- 1 y) lean men were randomly assigned to 
      2 crossover experiments in which they consumed either carbohydrate (CHO) or 
      carbohydrate plus protein and free leucine (CHO+Pro+Leu) after performing 30 min 
      of standardized activities of daily living. Primed, continuous infusions with 
      L-[ring-13C6]phenylalanine and L-[ring-2H2]tyrosine were applied, and blood and 
      muscle samples were collected to assess whole-body protein turnover and the 
      protein fractional synthetic rate in the vastus lateralis muscle over a 6-h 
      period. RESULTS: Whole-body phenylalanine and tyrosine flux were significantly 
      higher in the young than in the elderly men (P < 0.01). Protein balance was 
      negative in the CHO experiment but positive in the CHO+Pro+Leu experiment in both 
      groups. Mixed-muscle protein synthesis rates were significantly greater in the 
      CHO+Pro+Leu than in the CHO experiment in both the young (0.082 +/- 0.005%/h and 
      0.060 +/- 0.005%/h, respectively; P < 0.01) and the elderly (0.072 +/- 0.006%/h 
      and 0.043 +/- 0.003%/h, respectively; P < 0.01) subjects, with no significant 
      differences between groups. CONCLUSIONS: Co-ingestion of protein and leucine with 
      carbohydrate after activities of daily living improves whole-body protein 
      balance, and the increase in muscle protein synthesis rates is not significantly 
      different between lean young and elderly men.
FAU - Koopman, Rene
AU  - Koopman R
AD  - Department of Human Biology, Maastricht University, Maastricht, Netherlands. 
      r.koopman@hb.unimaas.nl
FAU - Verdijk, Lex
AU  - Verdijk L
FAU - Manders, Ralph J F
AU  - Manders RJ
FAU - Gijsen, Annemie P
AU  - Gijsen AP
FAU - Gorselink, Marchel
AU  - Gorselink M
FAU - Pijpers, Evelien
AU  - Pijpers E
FAU - Wagenmakers, Anton J M
AU  - Wagenmakers AJ
FAU - van Loon, Luc J C
AU  - van Loon LJ
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Am J Clin Nutr
JT  - The American journal of clinical nutrition
JID - 0376027
RN  - 0 (Carbon Isotopes)
RN  - 0 (Dietary Carbohydrates)
RN  - 0 (Dietary Proteins)
RN  - 0 (Muscle Proteins)
RN  - 42HK56048U (Tyrosine)
RN  - 47E5O17Y3R (Phenylalanine)
RN  - GMW67QNF9C (Leucine)
SB  - IM
MH  - Activities of Daily Living
MH  - Adult
MH  - Aged
MH  - *Aging/metabolism/physiology
MH  - Carbon Isotopes
MH  - Cross-Over Studies
MH  - Dietary Carbohydrates/administration & dosage/metabolism
MH  - Dietary Proteins/*administration & dosage/metabolism
MH  - Double-Blind Method
MH  - Humans
MH  - Leucine/*administration & dosage/metabolism
MH  - Male
MH  - Muscle Proteins/*biosynthesis/metabolism
MH  - Muscle, Skeletal/metabolism
MH  - Phenylalanine/blood
MH  - Tyrosine/blood
EDAT- 2006/09/09 09:00
MHDA- 2006/10/13 09:00
CRDT- 2006/09/09 09:00
PHST- 2006/09/09 09:00 [pubmed]
PHST- 2006/10/13 09:00 [medline]
PHST- 2006/09/09 09:00 [entrez]
AID - S0002-9165(23)29064-4 [pii]
AID - 10.1093/ajcn/84.3.623 [doi]
PST - ppublish
SO  - Am J Clin Nutr. 2006 Sep;84(3):623-32. doi: 10.1093/ajcn/84.3.623.