Postprandial Muscle Protein Synthesis Following Wheat Protein Ingestion in Vivo in Humans
Condition: Sarcopenia
MeSH terms: Sarcopenia
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      Aging is accompanied by a progressive decline in skeletal muscle mass. This age-related loss
      of muscle mass, or sarcopenia, is attributed to an imbalance between muscle protein synthesis
      and breakdown. As basal muscle protein synthesis rates do not seem to differ between young
      and elderly, most research has focused on potential impairments in the muscle protein
      synthetic response to the main anabolic stimuli, i.e. food intake and exercise. Skeletal
      muscle protein synthesis is highly responsive to food intake in healthy young adults. Recent
      data indicate that the muscle protein synthetic response to food intake may be blunted in the
      elderly. This proposed anabolic resistance is now being regarded as a key factor in the
      etiology of sarcopenia. Effective strategies to prevent and/or counteract the age-related
      loss of muscle mass include protein supplementation, preferably in combination with
      resistance exercise. Recent studies show the efficacy of dietary protein supplementation to
      improve muscle strength and function in frail elderly and to further augment the gains in
      muscle mass and function when combined with resistance exercise. As a consequence, nutrition
      research is now looking for the optimal amount, type, and timing of protein consumption to
      maximize postprandial muscle protein synthesis rates.

      Improvements in protein balance and/or higher muscle protein synthesis rates have been
      reported following the ingestion of various types of dietary protein: whey, casein, soy,
      casein hydrolysate, egg protein, and whole-milk and/or fat-free milk. It seems obvious to
      question which source of dietary protein is most effective in promoting muscle protein
      synthesis. There is only limited research comparing the efficacy of the ingestion of
      different proteins sources on the protein synthetic response. As such, it is difficult to
      identify a specific protein source that is most potentiating. This is further complicated by
      the fact that numerous parameters modulate the muscle protein synthetic response to protein
      ingestion. The amount and timing of protein administration, the amino acid composition of the
      protein, and the digestion and absorption kinetics of the protein source (or mixed meal), may
      all modulate the muscle protein synthetic response.

      Milk proteins, i.e. whey and casein, are the most widely studied dietary proteins. Casein and
      whey seem to have distinct anabolic properties, which are attributed to differences in
      digestion and absorption kinetics. Whey protein is a soluble protein that leads to fast
      intestinal absorption, whereas intact casein clots in the stomach delaying its digestion and
      absorption and the subsequent release of amino acids in the circulation. The faster, but more
      transient rise in plasma amino acid concentration after whey protein ingestion can lead to
      higher protein synthesis rates. In addition to intrinsic differences in digestion and
      absorption rate, it has been suggested that whey protein can more effectively stimulate
      protein synthesis due to its greater leucine content when compared to casein. 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. In this study we will assess the capacity of wheat protein
      ingestion as a means to increase postprandial muscle protein synthesis in vivo in humans. By
      directly comparing the anabolic properties of wheat protein or wheat protein hydrolysate with
      both casein and whey, we will determine the anabolic properties of wheat protein
      (hydrolysate) in vivo in older humans.
    

Intervention name(s): protein type and amount
Intervention type(s): Dietary Supplement
Intervention description(s): Subjects will stay in a supine position and consume a test beverage containing different amounts ans types of protein
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention