Effects of high versus standard essential amino acid intakes on whole-body protein turnover and mixed muscle protein synthesis during energy deficit: A randomized, crossover study

Abstract

Background & aims: Consuming 0.10-0.14 g essential amino acids (EAA)/kg/dose (0.25-0.30 g protein/kg/dose) maximally stimulates muscle protein synthesis (MPS) during energy balance. Whether consuming EAA beyond that amount enhances MPS and whole-body anabolism following energy deficit is unknown. The aims of this study were to determine the effects of standard and high EAA ingestion on mixed MPS and whole-body protein turnover following energy deficit.

Design: Nineteen males (mean ± SD; 23 ± 5 y; 25.4 ± 2.7 kg/m2) completed a randomized, double-blind crossover study consisting of two, 5-d energy deficits (-30 ± 4% of total energy requirements), separated by 14-d. Following each energy deficit, mixed MPS and whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and post-resistance exercise (RE) using primed, constant L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Beverages providing standard (0.1 g/kg, 7.87 ± 0.87 g) or high (0.3 g/kg, 23.5 ± 2.54 g) EAA were consumed post-RE. Circulating EAA were measured.

Results: Postabsorptive mixed MPS (%/h) at rest was not different (P = 0.67) between treatments. Independent of EAA, postprandial mixed MPS at rest (standard EAA, 0.055 ± 0.01; high EAA, 0.061 ± 0.02) and post-RE (standard EAA, 0.055 ± 0.01; high EAA, 0.065 ± 0.02) were greater than postabsorptive mixed MPS at rest (P = 0.02 and P = 0.01, respectively). Change in (Δ postabsorptive) whole-body (g/180 min) PS and PB was greater for high than standard EAA [mean treatment difference (95% CI), 3.4 (2.3, 4.4); P = 0.001 and -15.6 (-17.8, -13.5); P = 0.001, respectively]. NET was more positive for high than standard EAA [19.0 (17.3, 20.7); P = 0.001]. EAA concentrations were greater in high than standard EAA (P = 0.001).

Conclusions: These data demonstrate that high compared to standard EAA ingestion enhances whole-body protein status during underfeeding. However, the effects of consuming high and standard EAA on mixed MPS are the same during energy deficit.

Clinical trial registry: NCT03372928, https://clinicaltrials.gov.

Keywords: Energy deficit; Essential amino acids; Muscle protein synthesis; Protein; Whole-body protein turnover.

Conflict of interest statement

Conflicts of interest JAG, DDC, AHM, EEH, CTC, NEM, MAW, LMM, JWC, and SMP have no conflicts of interest associated with this research. The EAA formula used in this research is UAMS patent entitled “Essential Amino Acid Supplementation for Recovery of Muscle Strength and Function during Rehabilitation.” US Patent (9,364,463 B2; UAMS). Inventors are AAF and RRW. Neither AAF nor RRW were involved in data collection or analyses and were blinded to all data until final consolidation by JAG and SMP.

Published by Elsevier Ltd.