A Moderate Serving of a Lower-Quality, Incomplete Protein Does Not Stimulate Skeletal Muscle Protein Synthesis

Abstract

\n \n \n Dietary proteins can be broadly characterized by their origin (animal-or plant-based) and amino acid composition (complete vs. incomplete).\xa0Meals containing\xa0>\xa020\xa0g\xa0of high-quality, complete protein have repeatedly been shown to robustly stimulate skeletal muscle protein synthesis. However, breakfast in many Western countries is dominated by\xa0wheat-based products. Wheat and bread are considered a “lower-quality” incomplete source of protein, containing relatively low amounts of lysine and threonine. We hypothesized that a meal containing\xa0>\xa020\xa0g\xa0of wheat-based protein would offer no anabolic advantage over a control meal containing only 5\xa0g of plant-based protein.\n \n \n \n In a subset of healthy, middle-aged women from our recently completed trial (n\xa0=\xa06/17, 53\xa0± 7 y, 27\xa0± 2\xa0kg/m2), we measured post-prandial skeletal muscle protein synthesis, \xa0blood glucose, insulin and appetite for 3 h\xa0following the ingestion of: i) a wheat-based protein meal (INCOMPLETE: 717\xa0kcal, \xa023\xa0g protein, 120\xa0g carbohydrate, 16\xa0g fat) or ii) a low protein, plant-based, control meal (CONTROL: 542\xa0kcal, \xa05\xa0g protein, 86\xa0g carbohydrate and 23\xa0g fat). Venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed (2.0\xa0mmol/kg) constant infusion (0.08\xa0mmol/(kg/min)) of L-[ring-13C6]phenylalanine. All analyses were performed using established, standard techniques.\n \n \n \n Preliminary results indicate post-prandial skeletal muscle protein synthesis was similar in both cohorts (INCOMPLETE: 0.050\xa0± 0.012%/h vs. CONTROL: 0.054\xa0± 0.025%/h; p\xa0=\xa00.83) and consistent with fasting values historically measured by our lab.\xa0Blood glucose area under the curve (AUC; p\xa0=\xa00.82), insulin AUC (p\xa0=\xa00.85) and hunger AUC were similar in both cohorts.\n \n \n \n A moderate serving of incomplete protein failed to robustly stimulate skeletal muscle protein synthesis. Consumption of a higher-quality, \xa0completeprotein\xa0meal is likely required to acutely increase muscle protein anabolism.\n \n \n \n National Cattlemen s Beef Association\n