Postprandial Muscle Protein Synthesis Following Wheat Protein Ingestion in Vivo in Humans

Rationale: The progressive loss of skeletal muscle mass with aging, or sarcopenia, has a major impact on our health care system due to increased morbidity and greater need for hospitalization and/or institutionalization. One way to prevent skeletal muscle loss is to improve dietary intake of the elderly. Both whey and casein seem to offer an anabolic advantage over soy protein for promoting muscle hypertrophy. As a consequence it is assumed that (all) plant based proteins have less potent anabolic properties when compared with animal based proteins. However, there is little theoretical background for such assumptions. Objective: To provide evidence for the efficacy of wheat protein and wheat protein hydrolysate when compared with milk proteins (i.e. whey and casein) as a dietary protein to stimulate postprandial muscle protein synthesis in vivo in healthy older humans. Study design: double-blind, placebo-controlled intervention study Study population: 60 healthy non-obese (BMI 18.5-30 kg/m2) older males (age: 65-80 y) Intervention: A protein beverage (350 mL) containing 30 g of whey, casein, wheat protein, or wheat protein hydrolysate or 60 g of wheat protein hydrolysate will be consumed (n=12 per group). Main study parameters/endpoints: Primary study parameters include muscle protein synthesis rates. Secondary study parameters include whole-body protein synthesis, breakdown, oxidation, and net balance. Hypotheses: We hypothesize that ingestion of wheat protein hydrolysate results in a greater muscle protein synthetic response when compared with the intact wheat protein due to its faster digestion and absorption. Furthermore, ingestion of wheat protein hydrolysate results in a higher muscle protein synthetic response when compared with casein, but lower when compared with whey protein. Ingestion of 60 g of wheat protein hydrolysate (amount of leucine equal to 30 g of whey protein) will result in a similar muscle protein synthetic response compared to ingestion of 30 g of whey protein.