Consumption of Milk Protein or Whey Protein Results in a Similar Increase in Muscle Protein Synthesis in Middle Aged Men.
The differential ability of various milk protein fractions to stimulate muscle protein synthesis (MPS) has been previously described, with whey protein generally considered to be superior to other fractions. However, the relative ability of a whole milk protein to stimulate MPS has not been compared to whey. Sixteen healthy middle-aged males ingested either 20 g of milk protein (n = 8) or whey protein (n = 8) while undergoing a primed constant infusion of ring (13)C₆ phenylalanine. Muscle biopsies were obtained 120 min prior to consumption of the protein and 90 and 210 min afterwards. Resting myofibrillar fractional synthetic rates (FSR) were 0.019% ± 0.009% and 0.021% ± 0.018% h(-1) in the milk and whey groups respectively. For the first 90 min after protein ingestion the FSR increased (p < 0.001) to 0.057% ± 0.018% and 0.052% ± 0.024% h(-1) in the milk and whey groups respectively with no difference between groups (p = 0.810). FSR returned to baseline in both groups between 90 and 210 min after protein ingestion. Despite evidence of increased rate of digestion and leucine availability following the ingestion of whey protein, there was similar activation of MPS in middle-aged men with either 20 g of milk protein or whey protein.
Liggins Institute, University of Auckland, Auckland 1142, New Zealand. cameron.mitchell@auckland.ac.nz.
Cameron J
CJ
Mitchell
School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand. robinmcgregor@gmail.com.|Cardiovascular and Metabolic Disease Center, College of Medicine, Inje University, Busan 614-735, Korea. robinmcgregor@gmail.com.
Robin A
RA
McGregor
Liggins Institute, University of Auckland, Auckland 1142, New Zealand. r.dsouza@auckland.ac.nz.
Randall F
RF
D'Souza
Liggins Institute, University of Auckland, Auckland 1142, New Zealand. e.thorstensen@auckland.ac.nz.
Eric B
EB
Thorstensen
Liggins Institute, University of Auckland, Auckland 1142, New Zealand. j.markworth@auckland.ac.nz.
James F
JF
Markworth
Fonterra Research and Development Centre, Palmerston North 4442, New Zealand. Aaron.Fanning@fonterra.com.
Aaron C
AC
Fanning
School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand. s.poppitt@auckland.ac.nz.
Sally D
SD
Poppitt
Liggins Institute, University of Auckland, Auckland 1142, New Zealand. d.cameron-smith@auckland.ac.nz.
David
D
Cameron-Smith
D006801:Humans; D008297:Male; D008875:Middle Aged; D008894:Milk Proteins / Q000494:pharmacology*; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D000067816:Whey Proteins / Q000494:pharmacology
D008894:Milk Proteins; D009124:Muscle Proteins; D000067816:Whey Proteins
amino acids; fractional synthetic rate; milk protein; muscle; stable isotopes; whey protein