Exp Gerontol. 2006 Feb;41(2):215-9. Epub 2005 Nov 23.
Differential stimulation of muscle protein synthesis in elderly humans following isocaloric ingestion of amino acids or whey protein.
* Paddon-Jones D,
* Sheffield-Moore M,
* Katsanos CS,
* Zhang XJ,
* Wolfe RR.
Department of Surgery, The University of Texas Medical Branch, and Shriners Hospitals for Children, Galveston, Texas 77550, USA. djpaddon@utmb.edu
To counteract the debilitating progression of sarcopenia, a protein supplement should provide an energetically efficient anabolic stimulus. We quantified net muscle protein synthesis in healthy elderly individuals (65-79 yrs) following ingestion of an isocaloric intact whey protein supplement (WY; n=8) or an essential amino acid supplement (EAA; n=7). Femoral arterio-venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed, constant infusion of L-[ring-2H5]phenylalanine. Net phenylalanine uptake and mixed muscle fractional synthetic rate (FSR) were calculated during the post-absorptive period and for 3.5 h following ingestion of 15 g EAA or 15 g whey. After accounting for the residual increase in the intracellular phenylalanine pool, net post-prandial phenylalanine uptake was 53.4+/-9.7 mg phe leg-1 (EAA) and 21.7+/-4.6 mg phe leg-1 (WY), (P<0.05). Postabsorptive FSR values were 0.056+/-0.004% h-1 (EAA) and 0.049+/-0.006% h-1 (WY), (P>0.05). Both supplements stimulated FSR (P<0.05), but the increase was greatest in the EAA group with values of 0.088+/-0.011% h-1 (EAA) and 0.066+/-0.004% h-1 (WY), (P<0.05). While both EAA and WY supplements stimulated muscle protein synthesis, EAAs may provide a more energetically efficient nutritional supplement for elderly individuals.
PMID: 16310330 [PubMed - indexed for MEDLINE]
For composition of EAA and whey protein see table 2 in paper. Unfortunately there appears to be no mention of the brand(s) used in this study
