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Open AccessArticle

Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men

Graduate School of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
Graduate School of Human Development and Environment, Kobe University, Kobe, Hyogo 657-8501, Japan
Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya 466-8555, Japan
School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK
Author to whom correspondence should be addressed.
Nutrients 2018, 10(10), 1543;
Received: 27 August 2018 / Revised: 19 September 2018 / Accepted: 12 October 2018 / Published: 18 October 2018
Dietary protein intake is critical for the maintenance of skeletal muscle mass. Plasma amino acid concentrations increase with protein intake and increases in muscle protein synthesis are dependent on leucine concentrations. We aimed to investigate the effect of a mixed meal and free amino acids intake on plasma leucine concentrations. In this randomized crossover study, 10 healthy young men (age 25 ± 1 years, height 1.73 ± 0.02 m, weight 65.8 ± 1.5 kg) underwent tests under different conditions—intake of 2 g of leucine (LEU), intake of a mixed meal (protein 27.5 g, including 2.15 g of leucine, protein: fat: carbohydrate ratio—22:25:53) only (MEAL), intake of 2 g of leucine immediately after a mixed meal (MEAL-LEU) and intake of 2 g of leucine 180 min after a mixed meal (MEAL-LEU180). Blood samples were collected within 420 min (240 min for LEU only) after intake and changes in amino acid concentrations were evaluated. Although the maximum plasma leucine concentration increased to 442 ± 24 µM for LEU, it was lower at 347 ± 16 µM (p < 0.05 vs. LEU) for MEAL-LEU, 205 ± 8 µM (p < 0.05 vs. LEU) for MEAL. The maximum plasma leucine concentration for MEAL-LEU180 increased to 481 ± 27 µM and compared to LEU there was no significant difference (p > 0.1). The observation that rapid elevations in plasma leucine concentrations are suppressed when leucine is ingested at the same time as a meal suggests that the timing of its intake must be considered to maximize the anabolic response. View Full-Text
Keywords: leucine concentration; protein intake; mixed meal intake leucine concentration; protein intake; mixed meal intake
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MDPI and ACS Style

Yoshii, N.; Sato, K.; Ogasawara, R.; Nishimura, Y.; Shinohara, Y.; Fujita, S. Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men. Nutrients 2018, 10, 1543.

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