Effects of Intact and Hydrolyzed Pea Protein on Food Intake, Glycemic Response and Subjective Appetite
Condition: Diabetes Prevention; Obesity Prevention
Study type: Interventional
Phase: Phase 1

Summary: 
      The purpose of this protocol is to study the effects of intact and hydrolyzed yellow pea
      protein, compared to intact and hydrolyzed whey protein, on satiety, food intake, and glucose
      metabolism in healthy young men. The specific objective is to investigate the effects of 20 g
      available protein for 4 different protein types (intact and hydrolyzed pea and whey proteins)
      and water (control) on satiety, food intake and blood glucose before and after a meal. The
      specified amount of protein was chosen based on our previous studies on intact pea protein
      suggesting that 20 g may reduce food intake and pre-meal blood glucose 30 minutes before a
      test meal. Whey protein has been chosen as a reference protein because it has been
      extensively studied and its effects on blood glucose and food intake are being elucidated
      within our laboratory.
    

Detailed description: 
      According to the 2004 Canadian Community Health Survey, nearly two-thirds of Canadians are
      overweight or obese. Obesity is a major risk factor for the metabolic syndrome, which is
      linked to conditions such as type II diabetes. Dietary interventions that increase satiety
      (to promote weight loss) and maintain normal blood glucose levels are noninvasive and
      inexpensive compared to pharmacological strategies. Thus, it is important to identify
      types/sources of macronutrients that contribute to healthy body weight by increasing satiety
      and thereby reducing food intake. For instance, diets including pulses (legumes) have been
      linked with a lower risk of obesity/overweight.

      Pulses are the edible seeds of legumes or pod-bearing plants including dry beans, yellow
      peas, lentils and chickpeas. They are inexpensive healthy foods high in protein and complex
      carbohydrates. Recently within our laboratory, we found that including 5 cups of pulses into
      the diet for 8 weeks was associated with decreased body weight, waist circumference and
      improved glycemic control. However, the mechanisms driving weight loss and improved glycemic
      control need further investigation. For instance, pulses may affect satiety, energy intake
      and blood glucose because of their high amounts of protein. Protein is known to be more
      satiating than carbohydrate and fat leading to a positive impact on long-term body weight
      maintenance. Protein from various animal and plant sources has also been shown to stimulate
      the release of satiety-related hormones like insulin, glucagon, glucagon-like peptide-1
      (GLP-1), cholecystokinin (CCK), peptide tyrosine tyrosine (PYY) and ghrelin.

      The investigators recently investigated the independent dosage effects of pea protein (10 and
      20 g) and pea fibre (10 and 20 g) on ad libitum food intake at 30 minutes and pre- (0-30
      minutes) and post-meal (50-170 minutes) blood glucose response and subjective appetite in
      young men. Preliminary results indicate that increasing protein amounts (10 g versus 20 g)
      lead to decreased pre-meal blood glucose response and reduced food intake.

      Food-grade proteins are also available intact and/or hydrolyzed (partially digested through a
      controlled enzymatic process). Hydrolyzed proteins are more easily digested and absorbed,
      eliciting a faster rise in plasma amino acids compared to intact proteins and different
      hormonal and metabolic responses between the two forms. As for pea protein, no data are
      available differentiating the effects of intact and hydrolyzed forms on these blood
      parameters and appetite in humans. Moreover, the presence of bioactive polypeptides may be
      affected by protein formulation (i.e. the polypeptides may be cleaved/inactivated in
      hydrolyzed pea protein).

      Research is needed to determine whether the effect of pea protein differs on glycemic
      response and appetite both pre- and post-meal based on its form (intact versus hydrolyzed)
      and how it compares to other well-investigated proteins. This research is preliminary and may
      lead to future research in other population groups, including young women and overweight
      individuals. These results will encourage increased consumption of pulse fractions by
      providing a basis for the potential use of pea protein in the development of new functional
      foods aimed at preventing and managing obesity along with controlling blood glucose for
      diabetes management. Furthermore, results will show if pea protein is a comparable
      alternative to whey, which would be favorable for consumers shifting away from animal-derived
      proteins for health and/or environmental reasons.
    

Intervention name(s): Dietary intervention
Intervention type(s): Other
Intervention description(s): Dietary treatments with beverages
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: Food intake; Blood glucose; Pulses; Protein