Bioavailability of Protein and Amino Acids of Pea Protein Isolate in Healthy Volunteers
Condition: Proteins
Study type: Interventional

Summary: 
      The study aims to determine in healthy subjects the bioavailability of protein and amino
      acids of pea protein isolate and casein isolate. For this purpose, the investigators will
      compare two methods:

        1. the standard method consisting in measuring the ileal digestibility using ileal tubes,

        2. an alternative method that has been proposed by an Food and Agriculture Organization
           (FAO) expert group: the dual isotope method.
    

Detailed description: 
      2 groups of healthy volunteers are recruited (males and females from 18 to 65 y old), BMI
      from 18 to 30.

      Each group tests a protein source (30g) incorporated in a mashed potatoes that is divided in
      small portions to perform a repeated meal protocol. Protein sources (pea or casein) are
      intrinsically labeled with 15N and deuterium (2H).

      The day before the meal test, the volunteers are equipped with an intestinal tube that
      migrates until the ileum. On the day of the experiment, the position of the intestinal tube
      is checked by radiography in order to verify its location at the terminal ileum. A catheter
      is inserted in the forearm vein for blood sampling. A saline solution containing polyethylene
      glycol 4000 (PEG-4000, 20 g/L), used as a non-absorbable marker of the intestinal flow, is
      infused into the ileum in order to calculate the flow rate of the intestinal effluents. After
      a basal blood and urine sampling, as well as a basal collection of ileal effluents performed
      for 30 min, subject ingests at t=0 the first biscuit dose. The small meal portions are
      ingested every 30 min for 4h, to achieve an isotopic plateau. Tracer doses of carbon 13 (13C)
      amino acids are ingested concomitantly with the meal doses. Non-absorbable marker (inulin) is
      added to the test meal to correct for incomplete recovery at the ileal level.

      The postprandial sampling period lasts for 8 h after the meal ingestion. The intestinal
      content is continuously collected over ice and pooled every 30 min. Blood is sampled every 30
      min for 4 h, and hourly thereafter.Total urine is collected every 2 h.

      Measurements:

      In the effluents, the investigators measure PEG 4000, nitrogen (N) and 15N, carbon and 13C,
      amino acids (AA), 15N and 13C in amino acids and the non-absorbable markers of the meal. The
      investigators calculate the ileal flow rate, the overall real ileal protein digestibility and
      the real ileal digestibility of individual amino acids.

      In the plasma, the investigators measure uremia and 15N in urea, AA and protein to measure
      the transfer of dietary N in plasma protein pools; 15N, 2H and 13C in individual amino acids
      too measure the relative bioavailability of 15N/2H amino acids compared to free 13C amino
      acids.

      In the urine, the investigators measure urea and 15N in the urea ammonia to calculate the
      postprandial deamination losses.

      These measurements will allow to determine the protein and amino acid bioavailability from
      pea protein and compare it with casein, using the classical method implying ileal sampling
      and intrinsic tracer of dietary protein (15N). Additionally, it will allow to test a less
      invasive procedure using multiple tracers to assess the amino acid bioavailability.
    

Intervention name(s): Pea; Casein
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Proteins are intrinsically enriched with 15N and 2H. There are incorporated into mashed potatoes and the test meal is formulated to supply 30 g of pea protein per volunteer.; Proteins are intrinsically enriched with 15N and 2H. There are incorporated into mashed potatoes and the test meal is formulated to supply 30 g of pea protein per volunteer.
Intervention MeSH terms: Caseins
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Pea protein; Casein; Amino acid bioavailability; Protein digestibility; Isotopic tracers