The Impact of a Whole-food Animal-based Versus Plant-based Protein Rich Meal on Muscle Protein Synthesis
Condition: Muscle Protein Synthesis; Sarcopenia
MeSH terms: Sarcopenia
Study type: Interventional

Summary: 
      Rationale: Food intake stimulates muscle protein synthesis rates. The magnitude of the
      anabolic response to feeding forms a key factor in regulating muscle mass maintenance.
      Ingestion of animal-derived proteins generally leads to a greater stimulation of muscle
      protein synthesis when compared to the ingestion of plant-derived proteins. What is often
      neglected is that the anabolic properties of protein isolates do not necessarily reflect the
      anabolic response to the ingestion of the whole-foods from which those are derived. This
      discrepancy is due to the presence or absence of other components normally found within
      whole-food matrices, which influence protein digestion and amino acid absorption from animal
      based and plant based protein sources. A rapid and robust post-prandial release of
      food-derived amino acids is of particular relevance for older individuals, who typically show
      a blunted muscle protein synthetic response to feeding

      Objective: To compare the post-prandial muscle protein synthetic response following ingestion
      of a whole-food meal (560 kilo calorie (kCal); ~36 g protein total, ~0.45 g/kg body weight)
      containing ~100 g lean ground beef (~30 g protein) versus the ingestion of an isonitrogenous,
      isocaloric whole-food meal containing only plant-based protein sources (561 kCal; ~36 g
      protein total) in vivo in healthy, older men and women.

      Study design: randomized, counter-balanced, cross-over design, researchers and participants
      are not blinded, analysts are blinded.

      Study population: 16 healthy older (65-85 y) men and women (1:1 ratio of men:women)

      Intervention: Participants will undergo 2 test days. On one test day participants will
      consume a whole-food meal containing meat as the primary source of protein (~36 g, ~0.45 g/kg
      body weight). On the other day, participants will consume a whole-food meal containing only
      plant-based foods as the source of protein (~36 g or ~0.45 g/kg body weight). In addition, a
      continuous intravenous tracer infusion will be applied, and blood an muscle samples will be
      collected in order to assess the muscle protein synthetic response.

      Main study parameters/endpoints: The primary endpoint will be mixed muscle protein synthesis
      rates over the full 6h post-prandial period following meal ingestion.
    

Detailed description: 
      Food intake stimulates muscle protein synthesis rates. The anabolic response to feeding forms
      a key factor in regulating muscle mass maintenance. Impairments in the sensitivity of
      skeletal muscle tissue to respond to the anabolic properties of protein feeding have been
      reported in numerous settings where muscle mass is being lost, such as aging, disuse, chronic
      metabolic disease, and various clinical conditions where muscle wasting is apparent.

      The capacity of a dietary protein to stimulate post-prandial muscle protein accretion depends
      on the digestion and absorption kinetics of that protein as well as its amino acid
      composition. A more rapid rise in circulating essential amino acids (EAAs), with leucine in
      particular, drives the post-prandial rise in muscle protein synthesis rates. It has been
      suggested that plant and animal based protein sources do not have the same anabolic
      properties due to differences digestibility and essential amino acid composition. However, so
      far, nearly all studies evaluating the muscle protein synthetic response to food ingestion
      have applied a reductionist approach and have determined the muscle protein synthetic
      response to the ingestion of isolated protein sources (e.g., whey, casein, soy) with or
      without other isolated meal components (e.g., carbohydrates, fats). This work suggests that
      the ingestion of isolated animal-based proteins stimulates a superior muscle protein
      synthetic response when compared to the ingestion of isolated plant-based proteins. However,
      protein isolates never constitute the main protein portion of a meal. Perhaps more
      importantly, it is often neglected that the anabolic properties of protein isolates do not
      necessarily reflect the anabolic response to the ingestion of the whole-foods from which
      those are derived. This discrepancy is due to the presence or absence of other nutritional
      components within whole-food matrices. In particular, plant-derived protein sources contain
      anti-nutritional factors that impair protein digestion and amino acid absorption and, as
      such, compromise the post-prandial rise in muscle protein synthesis rates.

      Therefore, this project will compare the impact of the ingestion of a whole-food meal with
      beef as the primary source of protein, with the ingestion of a whole food meal ingestion with
      only plant derived protein sources, on the muscle protein synthetic response in healthy older
      men and women.
    

Intervention name(s): Muscle protein synthesis
Intervention type(s): Other
Intervention description(s): The meals contain a total of 0.45 g protein/kg body mass (36 g protein for an 80 kg person). To account for differences in body mass, the investigators will scale the meal content to ensure 0.45 g/kg body mass for different body mass ranges (i.e., 65-75 kg, 75-85 kg, etc.). As such, carbohydrate, fat, and total energy content of the meals will also be scaled to body mass. The test meals are composed out of regular whole food items which will be purchased from local shops. The muscle protein synthetic response following meal ingestion will be assessed by the use of stable isotope tracer methodology
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: The present study utilizes a randomized, counter-balanced, cross-over design in healthy older male and female participants. In total, 16 healthy older men and women (1:1 ratio of men:women) will participate in the study (20 including potential drop-out). Participants will be randomly assigned to either receive the meal including meat or exclusively plant based foods during the Test Day 1. During Test Day 2, participants will receive the other meal.
Masking: None (Open Label)
Primary purpose: Prevention