Protein, Calcium and Gut Hormone Secretion
Condition: Metabolic Disease
MeSH terms: Metabolic Diseases
Study type: Interventional

Summary: 
      Hormones that are produced by our stomach and intestines play a role in regulating our
      appetite and health, and are therefore of high interest for managing conditions such as
      obesity and Type 2 Diabetes (T2D). Two important hormones, called GLP-1 and PYY, are released
      from the same intestinal cell. The food we eat influences the release of these hormone and
      evidence suggests that protein and calcium are key nutrients that stimulate the secretion of
      GLP-1, while the influence of this combination on PYY release is less clear. Furthermore,
      gastric emptying affects the rate of absorption of nutrients and by manipulating the
      structural form of protein, in the absence or presence of calcium, we may be able to learn
      more about the processes mediating the gut hormone response. We hypothesise that gut hormone
      secretion will be enhanced following the ingestion of a partially digested protein in the
      presence of calcium versus a control protein without calcium. Additionally, the ingestion of
      the partially digested protein will result in faster gastric emptying compared to the control
      protein.
    

Detailed description: 
      Recent work at the University of Bath has shown that when ingested with 50 g whey protein
      hydrolysate, Capolac® (milk minerals high in calcium) potently stimulates availability of the
      important hormone glucagon-like peptide-1 (GLP-1). However, it is currently unclear how the
      form of protein ingested with the presence or absence of calcium may affect gut hormone
      secretion and gastric emptying. Therefore we aim to perform a study on the effect of
      co-ingesting two different forms of protein in the presence or absence of calcium on gut
      hormone availability and gastric emptying. This project will help provide key evidence to aid
      future work and recommendations for nutrition-based interventions for the prevention and
      management of obesity and T2D.

      Fifteen metabolically healthy men and women, age 18-65 years, BMI between 18.5 and 25 kg/m2
      will be recruited to participate in a randomised crossover study. Each participant will
      undergo 4 trials. Each trial will last ~3 hours and will be separated by a minimum of 48h:

      CONTROL (CON) - 30 g Control protein only CONTROL + CALCIUM (CON-C) - 30 g Control protein +
      9547 mg Capolac® (2500 mg of calcium ingested) PROTEIN (PRO) - 30 g Aggregate protein only
      PROTEIN + CALCIUM (PRO-C) - 30 g Aggregate protein + 9547 mg Capolac® (2500 mg of calcium
      ingested)

      Each of these drinks will also contain 500 mL of water, low calorie sweetener (80 mg
      sucralose) and will be labelled with 150 mg 13C1 sodium acetate, and 100 mg 13C1 sodium
      octanoate for the measurement of gastric emptying.

      Participants will be asked to arrive to the laboratory between 09:00 and 10:00 am after not
      eating for between 10-14 hours i.e. in a fasted state (water intake is permitted and
      encouraged). Upon arrival at the laboratory a trained phlebotomist staff member will insert a
      cannula (a small plastic tube) into a pre-heated dorsal hand vein on the back of the hand, or
      if unsuccessful, the antecubital vein. Participants will then be given one of the four test
      drinks, which once ingested will initiate the trial. Just after the ingestion of the test
      drink we will ask participants to fill out a palatability scale.

      Blood samples will be taken at baseline, and at 15, 30, 45, 60, 90, and 120 minutes after
      ingestion of the test drink. Breath samples will be collected in exetainers at baseline, and
      every 5 minutes until the 120-minute time point to determine gastric emptying. An appetite
      questionnaire will also be completed at baseline and every 60 minutes after ingestion of the
      test drink to assess appetite sensations. After the 120-minute time point participants will
      be asked to consume a lunch meal until they are comfortably full. Once satisfied with the
      lunch meal they will fill out the final appetite questionnaire. The trial day will then be
      complete. Following study completion participants will be asked to complete a restrained
      eating questionnaire.

      A subset of 5 participants will be fitted with a nasogastric tube by a qualified BAPEN nurse.
      5ml aspirate from the stomach will be samples at baseline, 30, 60, and 120 minutes which will
      be distributed equally for analyte profiling and in vitro culture work. 3 ml gastric aspirate
      will be used to stimulate a GLUTag cell line. Experiments will be performed by incubating
      cells with the neutralised gastric aspirate in 250 µl Krebs Ringer Buffer (KRB) for 2 h at
      37˚C, 5 % CO2. A second culture, identical to that previously described will be conducted,
      only with the addition of specific cell receptor antagonists.
    

Intervention name(s): Protein form
Intervention type(s): Dietary Supplement
Intervention description(s): Protein form and absence or presence of calcium manipulated
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: There are 4 conditions where participants will ingest different forms of protein in the presence or absence of calcium.
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science