Postprandial Effect of Breakfast Glycemic Index on Vascular Function, Insulinemia and Cognitive Performance (BGI Study)
Condition: Healthy
Study type: Interventional

Summary: 
      This is a crossover clinical trial aimed at adults (aged 20-40 years, with no cardiovascular
      disease), selected by consecutive sampling at urban primary care health clinics in Salamanca
      (Spain). Each subject will complete three interventions, with a washout period of one week:
      control breakfast (water), low glycemic index breakfast (apple, yogurt, walnuts and black
      chocolate) and high glycemic index breakfast (grape juice, bread and strawberry jam). The
      postprandial effect will be assessed at 60 and 120 minutes from each breakfast, measuring
      blood glucose and insulin and cognitive performance. Measurements will be performed of
      central blood pressure, augmentation index, pulse wave velocity, cardiac output and total
      peripheral vascular resistance at minutes (-10, 0, +15, +30, +45, +60, +75, +90, +105 and
      +120).
    

Detailed description: 
      Objectives:

      The primary objective of this study is to evaluate the postprandial effect of low and high
      glycemic index breakfasts on vascular function, measured by central blood pressure,
      augmentation index and pulse wave velocity, in a sample of healthy young adults. The second
      objective is to assess the postprandial effect of low and high glycemic index breakfasts on
      blood glucose and insulin values in a sample of healthy young adults. The third and last
      objective is to assess the postprandial effect of low and high glycemic index breakfasts on
      cognitive performance in a sample of healthy young adults.

      Design and setting:

      A controlled crossover clinical trial, where each subject will complete three interventions
      (control breakfast, high glycemic index breakfast and low glycemic index breakfast), with a
      washout period of one week between each, and whose order will be determined by a
      randomization sequence generated using the Randomization.com software
      (http://www.randomization.com).

      Study setting:

      The study will be conducted in the primary care health area of Salamanca in the Research Unit
      of La Alamedilla, belonging to the Spanish Network for Preventive Activities and Health
      Promotion (redIAPP) and Salamanca Institute for Biomedical Research (IBSAL).

      Study population:

      The subjects of the study population will be selected by consecutive sampling in the primary
      care clinics of urban health centers in Salamanca (Spain) between 2015 and 2016. As this
      crossover clinical trial, a consecutive sampling will ensure comparability of the groups.

      Intervention:

      Each of the three scheduled visits will last approximately 2 and a half hours, and will be
      structured as follows:

      Min -10: Measurement of clinical blood pressure, central blood pressure, and central
      hemodynamic parameters; evaluation of cognitive performance; laboratory test sampling to
      determine glucose and insulin blood levels.

      Min 0: Measurement of central blood pressure and central hemodynamic parameters; intake of
      assigned breakfast (10 minutes).

      Min +15, +30, +45: Measurement of central blood pressure and central hemodynamic parameters.

      Min +60: Measurement of central blood pressure and central hemodynamic parameters; evaluation
      of cognitive performance; laboratory test sampling to determine glucose and insulin blood
      levels.

      Min +75, +90, +105: Measurement of central blood pressure and central hemodynamic parameters.

      Min +120: Measurement of central blood pressure and central hemodynamic parameters;
      evaluation of cognitive performance; laboratory test sampling to determine glucose and
      insulin blood levels.
    

Intervention name(s): Control breakfast; High glycemic index breakfast; Low glycemic index breakfast
Intervention type(s): Other; Other; Other
Intervention description(s): It consists of 350 ml of water at room temperature.; It consists of 350 ml of water at room temperature, 200 ml of grape juice (with 136.28 kcal), 40 g of white bread (2 slices of 52.2 kcal each) and 29 g of strawberry jam (with 127.52 kcal); providing a total of 368.2 kcal.; It consists of 350 ml of water at room temperature, a 150 g apple (with 81.12 kcal), a 125 g low-fat natural yogurt (with 56.10 kcal), 3 shelled walnuts (with 38.94 kcal per unit) and 17.5 g of 72% black chocolate (with 102 kcal); supplying a total of 356.04 kcal.
Other intervention name(s): BF-1; BF-2; BF-3
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Other
Keywords: Glycemic Index; Postprandial Period; Vascular Stiffness; Blood glucose; Cognition