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Anabolic response with higher protein intake is largely achieved through suppression of protein breakdown in older adults
Author(s) -
Kim IlYoung,
Shin YunA,
Schutzler Scott,
Azhar Gohar,
Ferrando Arny A,
Wolfe Robert R
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1036.2
Subject(s) - anabolism , ingestion , medicine , endocrinology , basal (medicine) , meal , crossover study , stimulation , protein catabolism , muscle protein , chemistry , zoology , biology , skeletal muscle , biochemistry , amino acid , insulin , alternative medicine , pathology , placebo
Our recent metabolic study demonstrated in young healthy adults that whole body net protein accretion was greater with ingestion of a mixed meal containing ~70g vs. ~40g protein, the latter of which has previously been shown to stimulate a near maximal synthetic response in muscle. To test this relationship in aging adults, we determined whole body protein kinetics in eight older adults (69±5y, 83±14kg, 27±10kg/m 2 ) with a crossover design in the fasted state and following ingestion of 35g (moderate protein, or MP) or 70g (higher protein, HP) protein in mixed meals. Whole body protein kinetics [i.e., protein synthesis (PS), breakdown (PB), and net balance (NB)] (mg/kg LBM/min)] were expressed as changes from fasted to fed states. Feeding resulted in positive NB at both levels of protein intake (for all; p<0.0001) but to a greater extent with HP (p<0.0001). NB was increased primarily through a greater reduction in PB (p<0.0001) and to a lesser extent the stimulation of PS (p<0.01). The increase in NB in the MP group was entirely due to a suppression of breakdown, as synthesis was not stimulated above the basal state (p>0.10). Importantly, linear relationship was observed between NB and the amount of protein intake (g/kg LBM) per meal (r = 0.997, p<0.0001). In conclusion, as in the healthy young adults, we found in older adults that the whole body anabolic response increases linearly with increasing amount of dietary protein without showing a sign of plateau, largely through a greater suppression of protein breakdown. Support or Funding Information The project was financially supported by Award Number UL1‐TR‐000039 and KL2‐TR‐000063 from the National Center for Advancing Translational Science (NCATS).