Plain English Summary
Background and study aims
Hypertension (high blood pressure) is one of the main causes of cardiovascular disease, hospitalization and also a cause of death in developed countries. It has been extensively recognised that lifestyle change is the first step in the prevention (especially in those individuals with normal blood pressure) but also in the control of hypertension. Several changes in lifestyle such as quitting smoking, weight loss in overweight individuals, moderate alcohol consumption and following a healthy diet rich in vegetables and fruits, low in meat and processed food and moderate in low fat dairy products, and reducing salt intake are considered important to control hypertension. Gamma aminobutyric acid (GABA), a bioactive component is known for its role in regulation of blood pressure, neurotransmission (transmission of signals in brain cells), calming and diuretic (substance that promotes the production of urine which may decrease blood pressure) properties. Because of these and other beneficial properties, different food products enriched with GABA have been proposed as potential functional foods. Recently, our group has produced bread with lower glycemic index (low blood sugar levels) than traditional bread, fermented with bacteria that produce GABA and partially substituting sodium chloride (common salt) by potassium salts. This bread could have beneficial effects on blood pressure, insulin resistance and endothelial (thin layer of cells that line the interior surface of blood vessels which reduces friction of the flow of blood allowing the fluid to be pumped further) function. Therefore, the main aim of the present study is to assess the effect of bread reduced in sodium chloride and enriched with potassium salts and rich in GABA on blood pressure, insulin resistance, inflammation and endothelial function on subjects with prehypertension, or light or moderate hypertension.
Who can participate?
The study will include 30 men and women with pre-hypertension but who are not taking antihypertensive medication aged between 18 and 65 years.
What does the study involve?
All the participants will be randomly assigned to three interventions, each of four weeks duration:
1. Dietary recommendations + traditional bread
2. Dietary recommendations + bread reduced in sodium chloride and enriched with potassium salts
3. Dietary recommendations + bread reduced in sodium chloride and enriched with potassium salts and containing 20 mg/100g of GABA.
What are the possible benefits and risks of participating?
The benefits for the participants are mainly that they will receive dietary counselling to follow a healthy diet by trained dietitians and also this study will help them to control the blood pressure. However, we cannot confirm that all participants will receive a direct benefit from the present study. But the study will provide further knowledge in relation to the consumption of different types of bread in the control of blood pressure, glucose and insulin metabolism and endothelial function. The main risk for the participant is that they could experience slight burning sensation during the blood test and also a hematoma (bruising) can appear. Rarely, they could suffer from sickness. However, the amount of blood sample taken is relatively small (65 ml).
Where is the study run from?
This study is conducted in the Hospital Sant Joan de Reus (Reus, Spain). The study is led by the Nutrition Unit, Faculty of Medicine and Health Science, IISPV, University Rovira i Virgili (Spain), and CIBERobn (P.I. Jordi Salas-Salvadó) with the collaboration of Vascular Medicine and Metabolism Unit, Lipids and Atherosclerosis Research Unit, Sant Joan University Hospital, IISPV, Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Barcelona, Spain.
When is the study starting and how long is it expected to run for?
The study started in March 2013 and it is expected to finish in March 2014. The study will be recruiting participants from March 2013 until October 2013.
Who is funding the study?
The study is financed by Europastry, S.A.
Who is the main contact?
Prof. Jordi Salas-Salvadó
Effect of functional bread reduced in salt and fermented with dough containing lactobacillus brevis forming gamma-aminobutyric acid, on blood pressure, glucose metabolism and endothelial function
Regular consumption of bread enriched with gamma-aminobutyric acid (GABA) and reduced in sodium chloride will have a short and medium term hypotensive effect compared to the consumption of traditional bread or bread reduced in sodium chloride.
Sant Joan Hospital Ethical Committee, 31/01/2013, ref: 13-01-31/1proj3
Randomised crossover double-blind clinical trial
Primary study design
Secondary study design
Randomised cross over trial
Patient information sheet
Not available in web format, please contact firstname.lastname@example.org to request a patient information sheet
1. Healthy dietary recommendations + traditional bread
2. Healthy dietary recommendations + bread reduced in sodium chloride
3. Healthy dietary recommendations + bread reduced in sodium chloride fermented with Lactobacillus Brevis
120 g/day of bread in each intervention period.
Duration of intervention: 4 weeks for each of the three interventions.
Primary outcome measure
Daily mean blood pressure measured by a 24 hour continuous register at baseline and at the end of each intervention period (after one month).
Secondary outcome measures
1. Blood pressure during activity and sleeping period
2. Blood pressure during the three hours after consuming the bread at morning.
3. Fasting glycemia, insulinemia and Homeostatic Measurement Assessment-Insulin Resistance (HOMA-IR)
4. Endothelial function and peripheral inflammation measured by biochemical markers.
5. Endothelial function measured by the Endo-PAT method
6. Adherence to the intervention
7. Tolerance and safety
Measured at baseline and at the end of each intervention period (after one month)
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Patients (male and female) aged between 18 and 65 years with pre-hypertension but without antihypertensive medication
Target number of participants
30; male and female
Participant exclusion criteria
1. Severe hypertension (systolic blood pressure ≥ 160 mmHg, diastolic blood pressure ≥ 100 mmHg)
2. Type 2 diabetes
3. Body mass index (BMI) >35 kg/m^2
4. Target organ injuries attributed to hypertension
5. Inflammatory or infectious disease
6. Anti-inflammatory or antibiotic drugs
7. Alcoholism or drug abuse
8. Recent hypocaloric diet
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Universitat Rovira i Virgili
Pza Xavier Cugat
2 Ed. C
Planta 4 Parc Sant Cugat Nord
Sant Cugat del Vallès
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
2015 results in: http://www.ncbi.nlm.nih.gov/pubmed/26579797