The Postprandial Effects of Chick-Pea Consumption on Glucose, Insulin, and Gut Hormone Responses (PEA-POD).
Condition: Postprandial Period
Study type: Interventional

Summary: 
      Pulses have a high fibre content, contribute to lowering fasting blood cholesterol levels and
      improving glycaemic control, and have shown also considerable promise in supporting the
      dietary management of cardiovascular disease (CVD), type-2 diabetes mellitus (T2DM) and
      obesity. It is now established that cellular integrity (maintenance of cell wall structure)
      is a key factor responsible for the low glycaemic index (GI) of pulses. The maintenance of
      the cell wall structure restricts starch digestion and therefore glucose production in the
      gut. Thus, cell damage results in a loss of such properties and also the potential health
      benefits to consumers.

      This knowledge has presented an opportunity to exploit alternative processing techniques for
      the manufacture of pulse-based ingredients. We have successfully created a dry powder
      consisting predominantly of intact cells which still retains low digestibility (>60%
      resistant starch). This chickpea powder (CPP) was found to be stable under long-term storage,
      has a neutral taste and aroma, and showed promise as a low GI 'flour-substitute'.

      This study will investigate blood sugar, insulin and gut hormone levels (post-prandial
      glycaemic, insulinaemic and hormone responses) following the consumption of CPP consumed at
      breakfast, as a drink and incorporated into a food matrix (bread).
    

Detailed description: 
      The nutritional and potential long-term health benefits of consuming pulses have been well
      documented. Pulses have a high fibre content, contribute to lowering fasting blood
      cholesterol levels and improving glycaemic control, and have shown also considerable promise
      in supporting the dietary management of cardiovascular disease (CVD), type-2 diabetes
      mellitus (T2DM) and obesity. They are gluten-free and are also an affordable and accessible
      source of starch, protein, and dietary fibre. It is now established that cellular integrity
      (maintenance of cell wall structure) is a key factor responsible for the low glycaemic index
      (GI) of pulses. The maintenance of the cell wall structure restricts starch digestion and
      therefore glucose production in the gut. Thus, cell damage (i.e. as occurs extensively during
      milling of pulses into flour) results in a loss of such properties and also the potential
      health benefits to consumers.

      This knowledge has presented an opportunity to exploit alternative processing techniques for
      the manufacture of pulse-based ingredients that preserve the desirable low GI of whole
      pulses. Incorporation of such ingredients has the potential to lower the glycaemic and
      insulinaemic responses to staple food products and/or may promote satiety, thereby
      ameliorating the dietary management of T2D and obesity and reducing the risk factors
      associated with these diseases. Building on new understanding of the conditions required to
      preserve cellular integrity, we have successfully created a dry powder consisting
      predominantly of intact cells which still retains low digestibility (>60% resistant starch).
      This chickpea powder (CPP) was found to be stable under long-term storage, has a neutral
      taste and aroma, and showed promise as a low GI 'flour-substitute'.

      This study will investigate blood sugar, insulin and gut hormone levels (post-prandial
      glycaemic, insulinaemic and hormone responses) following the consumption of CPP consumed as a
      drink and incorporated into a food matrix (bread). It is hypothesised that the structure of
      the CCP will result in a reduced post-prandial glycaemic response, while maintaining (or
      improving) the insulinaemic and gut hormone responses. This regulation of blood sugar levels
      following a meal would be beneficial for people with impaired glucose metabolism, such as
      T2DM. This study will consist of two phases, both utilising a three-arm, random crossover
      design.

      Phase 1 aims to test the glucose response to unmodified CPP (i.e. has not been cooked). This
      will involve the consumption of the following test drinks containing 50g of available
      carbohydrate (i.e. starch and/or sugars): (1) Glucose (an oral glucose tolerance test, OGTT);
      (2) Control chickpea product (no cellular integrity); and (3) the CPP. These test drinks will
      be consumed in random order on three separate visits. In order to ensure the test
      carbohydrates remains in solution, all test drinks will be made up in an equivalent volume of
      330 ml (bottled water) containing chocolate flavouring. Participants will be required to fast
      overnight, a capillary blood glucose measurement will be taken at t=0, followed by
      consumption of the test drink within 5 min. Further capillary blood glucose measurements will
      be taken at t=10, 20, 30, 45, 60, 90, and 120 min. Additionally, participants will be
      provided with a Constant Glucose Monitor (CGM) that will be applied to the upper arm 24hrs
      prior to the first study day. All three study visits will be completed in 12 days (The length
      of CGM activity). It is hypothesised that the cell wall integrity in the CPP drink will
      result in a reduced post-prandial glycaemic response compared to the control chickpea product
      and the OGTT standard.

      Outcome measures: The primary outcome of Phase 1 will be the glycaemic response to the
      consumption of CPP drink compared to both the OGTT and control chickpea product. In vitro
      studies suggest that maintenance of cellular integrity will reduce the early phase of
      post-prandial glycaemia, as assessed by the incremental area under the curve (iAUC)
      iAUC0-60min and maximum blood glucose concentration (Cmax). Secondary measures such as the
      time to reach maximum blood glucose concentration (Tmax), iAUC0-120min and iAUC60-120min will
      also be assessed.

      Phase 2 aims to test the glucose, insulin and gut hormone response to CPP incorporated into a
      staple food. This will involve the consumption of wheat-based breads containing 50g of
      available carbohydrate and either; (1) wheat bread (control) (2) wheat bread with 30% CPP
      substitution of wheat flour, and (3) wheat bread with 60% CPP substitution of wheat flour.
      These breads will be consumed as part of a breakfast following an overnight fast on three
      separate study visits. Post-prandial concentrations of plasma glucose, insulin,
      glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide 1 (GLP-1), peptide YY
      (PYY) and C-peptide will be measured; at commencement of meal, t=0, and following consumption
      at, t=15, 30, 45, 60, 90, 120, 180, and 240 min. Additionally, participants will be provided
      with a Constant Glucose Monitor (CGM) that will be applied to the upper arm 24hrs prior to
      each study day.

      Outcome measures: The primary outcome of Phase 2 will be iAUC0-60min for plasma glucose
      concentrations and corresponding plasma insulin/C-peptide responses, demonstrating the
      ability of cell wall integrity to limit starch digestion, and therefore, the rate of glucose
      appearance in the blood in the early phase of post-prandial glycaemia. Secondary outcome
      variables include iAUC0-120min, iAUC0-240min, 30-90 and 90-240, Cmax, Tmax changes from
      baseline up to 240 min for plasma glucose, insulin, and C-peptide concentrations. For the gut
      hormones plasma GIP, PYY and GLP-1 concentrations will be assessed using the same outcome
      variables. Subjective measures of study meals and ad libitum meal palatability will be
      collected at t=10 min and post lunch, respectively. Subjective measures of mood, satiety and
      digestive comfort will be collected t=0, 10, 30, 60, 120, 180, 210, 240 min and post lunch.
      The energy intake from the ad libitum lunch provided following the experimental period will
      also be compared. Subjective measures will be summarised using descriptive statistics.
    

Intervention name(s): Chickpea powder
Intervention type(s): Dietary Supplement
Intervention description(s): Chickpea powder is produce using novel production techniques to maintain chickpea cell structure. It will be incorporated into a drink (Dextrose control), or baked into bread rolls at 30% or 60% substitution of wheat flour(100% Wheat flour control).
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Cross-over design: Each participant will receive a control plus 2 treatments
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: Chickpea; Cell Wall; Dietary Fibre; Postprandial; Metabolism; Enteroendocrine