Postprandial Effect of Breakfast Glycemic Index on Vascular Function, Insulinemia and Cognitive Performance (BGI Study)

Study Overview
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Brief Summary
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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
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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.

Official Title
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Postprandial Effect of Breakfast Glycemic Index on Vascular Function, Insulinemia and Cognitive Performance, a Crossover Clinical Trial (BGI Study)

Conditions
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Healthy

Intervention / Treatment
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* Other: Control breakfast
* Other: High glycemic index breakfast
* Other: Low glycemic index breakfast


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Young adults. Aged between 20 and 40 years. Both sexes. Those agree to sign the informed consent. Exclusion Criteria: History of cardiovascular events (acute myocardial infarction, stroke, etc.). History of hypertension, diabetes mellitus or dyslipidemia. Pharmacological treatment for any of the above conditions. Diagnosis of clinically demonstrable neurological and/or neuropsychological disease. Excessive consumption of toxic substances. Celiac patients and/or those intolerant to lactose. Subjects on a low-calorie and/or low-sodium diet. Pregnant women. Those with any other circumstance that the investigators consider could interfere with the study procedures.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Control<br>Control breakfast | Other: Control breakfast<br>* It consists of 350 ml of water at room temperature.<br>* Other names: BF-1;Other: High glycemic index breakfast<br>* 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.<br>* Other names: BF-2;Other: Low glycemic index breakfast<br>* 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.<br>* Other names: BF-3;|
| Experimental: Intervention 1<br>High glycemic index breakfast | Other: Control breakfast<br>* It consists of 350 ml of water at room temperature.<br>* Other names: BF-1;Other: High glycemic index breakfast<br>* 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.<br>* Other names: BF-2;Other: Low glycemic index breakfast<br>* 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.<br>* Other names: BF-3;|
| Experimental: Intervention 2<br>Low glycemic index breakfast | Other: Control breakfast<br>* It consists of 350 ml of water at room temperature.<br>* Other names: BF-1;Other: High glycemic index breakfast<br>* 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.<br>* Other names: BF-2;Other: Low glycemic index breakfast<br>* 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.<br>* Other names: BF-3;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Augmentation index | Measurement by Mobil-O-Graph® device | Changes in augmentation index at 1 week, according to glycemic index of the breakfast | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Central blood pressure | Measurement by Mobil-O-Graph® device | Changes in central blood pressure at 1 week, according to glycemic index of the breakfast | 
| Pulse wave velocity | Measurement by Mobil-O-Graph® device | Changes in pulse wave velocity at 1 week, according to glycemic index of the breakfast | 
| Blood glucose | Measurement by laboratory test sampling | Changes in blood glucose at 1 week, according to glycemic index of the breakfast | 
| Insulin values | Measurement by laboratory test sampling | Changes in insulin values at 1 week, according to glycemic index of the breakfast | 
| Immediate verbal memory | Assessment by immediate recall of a list of 15 words, in three attempts | Changes in immediate verbal memory at 1 week, according to glycemic index of the breakfast | 
| Delayed verbal memory | Assessment by free recall of the words learnt in the first part of the study after a period of approximately 10 minutes | Changes in delayed verbal memory at 1 week, according to glycemic index of the breakfast | 
| Phonological fluency | Assessment by enumerating for one minute as many words as possible starting with different letters | Changes in phonological fluency at 1 week, according to glycemic index of the breakfast | 
| Attention | Assessment by Trail Making Test A | Changes in attention at 1 week, according to glycemic index of the breakfast | 
| Processing speed | Assessment by Trail Making Test B | Changes in processing speed at 1 week, according to glycemic index of the breakfast | 
| Executive functions | Assessment by Trail Making Test B | Changes in executive functions at 1 week, according to glycemic index of the breakfast | 
| Working memory | Assessment by WAIS Digit Span Backward test | Changes in working memory at 1 week, according to glycemic index of the breakfast | 
| Sustained attention | Assessment by Stroop test | Changes in sustained attention at 1 week, according to glycemic index of the breakfast | 
| Selective attention | Assessment by Stroop test | Changes in selective attention at 1 week, according to glycemic index of the breakfast | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Glycemic Index, Postprandial Period, Vascular Stiffness, Blood glucose, Cognition