Fifteen elderly people took part in the trial, which found improvements in the levels of phenylalanine – a measure of muscle protein accumulation, according to findings published in the journal Nutrition Research.
“This finding may have practical implications for the formulation of nutritional supplements to enhance muscle anabolism in older individuals,” wrote lead author Christos Katsanos from Arizona State University.
The participants (average age 65.7) received a bolus containing whey protein (WY, 15 grams), the constituent essential amino acids (EAA, 6.72 grams), or the non-essential amino acids (NEAA, 7.57 grams). During the 3.5 hours that followed ingestion of the bolus, the researchers measured the phenylalanine balance in the subjects.
Katsanos and his co-workers report that only subjects in the whey group experienced improvements in the phenylalanine balance, from -216 to -105 nanomoles per minute per kilograms of lean leg mass. In the essential and non-essential amino acid groups, phenylalanine balance changed from −203 to −172, and from −203 to −204 nanomoles per minute per kilograms of lean leg mass, respectively.
“The most important finding of this study is that WY, at least in the amount ingested in this study, results in greater anabolic effect in elderly persons than its EAA,” wrote the researchers.
“Therefore, this suggests that WY ingestion improves muscle protein accretion in elderly persons through mechanisms that are beyond those associated with its EAA content.”
Source: Nutrition ResearchOctober 2008, Volume 28, Issue 10, Pages 651-658“Whey protein ingestion in elderly persons results in greater muscle protein accrual than ingestion of its constituent essential amino acid content”
Authors: C.S. Katsanos, D.L. Chinkes, D. Paddon-Jones, X.-j. Zhang, A. Aarsland, R.R. Wolfe