madman
Super Moderator
Whey Protein Hydrolysate Increases Amino Acid Uptake, mTORC1 Signaling, and Protein Synthesis in Skeletal Muscle of Healthy Young Men in a Randomized Crossover Trial
ABSTRACT
Background: Muscle protein synthesis (MPS) can be stimulated by ingestion of protein sources, such as whey, casein, or soy. Protein supplementation can enhance muscle protein synthesis after exercise and may preserve skeletal muscle mass and function in aging adults. Therefore, identifying protein sources with higher anabolic potency is of high significance.
Objective: The aim of this study was to determine the anabolic potency and efficacy of a novel whey protein hydrolysate mixture (WPH) on mechanistic target of rapamycin complex 1 (mTORC1) signaling and skeletal MPS in healthy young subjects.
Methods: Ten young men (aged 28.7 ± 3.6 y, 25.2 ± 2.9 kg/m2 body mass index [BMI]) were recruited into a double blind two-way crossover trial. Subjects were randomized to receive either 0.08 g/kg of body weight (BW) of WPH or an intact whey protein (WHEY) mixture during stable isotope infusion experiments. Fractional synthetic rate, leucine and phenylalanine kinetics, and markers of amino acid sensing were assessed as primary outcomes before and 1–3 h after protein ingestion using a repeated measures mixed model.
Results: Blood leucine concentration, delivery of leucine to muscle, transport of leucine from blood into muscle and intracellular muscle leucine concentration significantly increased to a similar extent 1 h after ingestion of both mixtures (P < 0.05). Phosphorylation of S6K1 (i.e. a marker of mTORC1 activation) increased equally by ∼20% 1-h post ingestion (P < 0.05). Ingestion of WPH and WHEY increased mixed MPS similarly in both groups by ∼43% (P < 0.05); however, phenylalanine utilization for synthesis increased in both treatments 1-h post ingestion but remained elevated 3-h post ingestion only in the WPH group (P < 0.05).
Conclusions: We conclude that a small dose of WPH effectively increases leucine transport into muscle, activating mTORC1 and stimulating MPS in young men. WPH anabolic potency and efficacy for promoting overall muscle protein anabolism is similar to WHEY, an intact protein source. This trial was registered at clinicaltrials.gov as NCT03313830. J Nutr 2019;00:1–10
In summary, we found that WPH ingestion leads to amino acid transport into muscle, activation of mTORC1 signaling, and an increase in the rate of MPS. This stimulation of muscle protein anabolism was similar to that observed following ingestion of intact WHEY protein. Of interest is that this response occurred at relatively small dosages in comparison to currently used doses of protein or EAA supplements. Although the overall muscle protein anabolic response was similar between WPH and WHEY, the utilization of the 3-pool model allowed us to discover some important differences between the 2 beverages. For example, WPH induced a greater transport and accumulation of leucine into muscle which increased amino acid utilization for protein synthesis compared with WHEY. We conclude that the bioactive peptides contained in the hydrolyzed form of whey can be easily digested and absorbed compared with a whole protein source, and may be an alternative nutritional strategy to improve protein synthesis in clinical conditions associated with muscle wasting.
ABSTRACT
Background: Muscle protein synthesis (MPS) can be stimulated by ingestion of protein sources, such as whey, casein, or soy. Protein supplementation can enhance muscle protein synthesis after exercise and may preserve skeletal muscle mass and function in aging adults. Therefore, identifying protein sources with higher anabolic potency is of high significance.
Objective: The aim of this study was to determine the anabolic potency and efficacy of a novel whey protein hydrolysate mixture (WPH) on mechanistic target of rapamycin complex 1 (mTORC1) signaling and skeletal MPS in healthy young subjects.
Methods: Ten young men (aged 28.7 ± 3.6 y, 25.2 ± 2.9 kg/m2 body mass index [BMI]) were recruited into a double blind two-way crossover trial. Subjects were randomized to receive either 0.08 g/kg of body weight (BW) of WPH or an intact whey protein (WHEY) mixture during stable isotope infusion experiments. Fractional synthetic rate, leucine and phenylalanine kinetics, and markers of amino acid sensing were assessed as primary outcomes before and 1–3 h after protein ingestion using a repeated measures mixed model.
Results: Blood leucine concentration, delivery of leucine to muscle, transport of leucine from blood into muscle and intracellular muscle leucine concentration significantly increased to a similar extent 1 h after ingestion of both mixtures (P < 0.05). Phosphorylation of S6K1 (i.e. a marker of mTORC1 activation) increased equally by ∼20% 1-h post ingestion (P < 0.05). Ingestion of WPH and WHEY increased mixed MPS similarly in both groups by ∼43% (P < 0.05); however, phenylalanine utilization for synthesis increased in both treatments 1-h post ingestion but remained elevated 3-h post ingestion only in the WPH group (P < 0.05).
Conclusions: We conclude that a small dose of WPH effectively increases leucine transport into muscle, activating mTORC1 and stimulating MPS in young men. WPH anabolic potency and efficacy for promoting overall muscle protein anabolism is similar to WHEY, an intact protein source. This trial was registered at clinicaltrials.gov as NCT03313830. J Nutr 2019;00:1–10
In summary, we found that WPH ingestion leads to amino acid transport into muscle, activation of mTORC1 signaling, and an increase in the rate of MPS. This stimulation of muscle protein anabolism was similar to that observed following ingestion of intact WHEY protein. Of interest is that this response occurred at relatively small dosages in comparison to currently used doses of protein or EAA supplements. Although the overall muscle protein anabolic response was similar between WPH and WHEY, the utilization of the 3-pool model allowed us to discover some important differences between the 2 beverages. For example, WPH induced a greater transport and accumulation of leucine into muscle which increased amino acid utilization for protein synthesis compared with WHEY. We conclude that the bioactive peptides contained in the hydrolyzed form of whey can be easily digested and absorbed compared with a whole protein source, and may be an alternative nutritional strategy to improve protein synthesis in clinical conditions associated with muscle wasting.
