Plain English Summary
Background and study aims
Several studies have reported the health benefits of grape pomace (GP) supplementation since it is a dietary source of polyphenols and fiber. GP is a good candidate for a clinical trial of the management of both blood pressure and glucose levels. Moreover, grape pomace has promising sensory potential as a condiment in food but this property is still not scientifically proven. This trial is included in a R+D+i Project (INGRAPE) funded by the Spanish Ministry of Science and Innovation, the aim of which is to assess the use of GP seasoning as a salt replacer in foods to reduce markers of high blood pressure and high blood sugar in people at risk.
Who can participate?
Participants with at least two of the following risk factors: high blood pressure (systolic ≥130 mmHg or diastolic >85 mmHg), high blood cholesterol (HDL cholesterol <40 mg/dl in men and <50 mg/dl in women), high blood fats (triglycerides >150 mg/dl), increased fasting blood sugar (>100 mg/dl), increased waist size (> 94 cm in men and > 80 cm in women)
What does the study involve?
Participants will undergo 6 weeks of reducing salt in their food (control group) or supplementation with 2 g/day of grape pomace seasoning as a salt replacer (treatment group). Participants provide samples of faeces, saliva and blood for analysis at the start and the end of the study.
What are the possible benefits and risks of participating?
The researchers expect the GP seasoning to reduce blood pressure and blood sugar levels and cause changes in gut bacteria. Therefore, the participants in the intervention group will benefit from these potential health effects. In a general way, all participants will get satisfaction from contributing to a study that could lead to an interesting strategy to manage high blood pressure and blood sugar. As far as the researchers are aware, participating does not lead to additional risks.
Where is the study run from?
CIAL-Institute of Food Science Research, Spanish National Council (CSIC) (Spain)
When is the study starting and how long is it expected to run for?
December 2016 to November 2019
Who is funding the study?
Spanish Ministry of Science and Innovation (Spain)
Who is the main contact?
1. Diego Taladrid
2. Begoña Bartolomé
3. Dr M. Victoria Moreno Arribas
Nutritional intervention with a new seasoning from grape pomace in people at risk of metabolic syndrome to manage blood pressure and glycaemia
Grape pomace has demonstrated before its functional properties in the management of risk factors of metabolic syndrome. Moreover, grape pomace has an underestimated culinary potential.
Approved 16/05/2017, The Spanish National Research Council Ethics Committee (117 Serrano Street, Madrid, 28006, Spain; +34 (0)915681494; firstname.lastname@example.org), ref: RTC-2016-4556-1
Interventional controlled randomized controlled trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not avaliable in web format, please use contact details to request a participant information sheet
Management of metabolic risk factors of metabolic syndrome
First, volunteers will receive information about the study, a survey of dietary habits and several recipes low in sodium salt. In addition, they will have to sign a printed consent to participate in the study, donate their biological samples and to ensure confidentially of the data.
Then, participants will be allocated randomly to the control and treatment groups. All of them will go through a washout period in which they will have to reduce their intake of polyphenol-rich foods for 2 weeks. After that, both sets of volunteers will have to reduce the consumption of sodium salt during the 6 weeks of the clinical trial. Furthermore, the treatment group will have to consume 2 g/day of grape pomace as sodium salt replacer in their foods.
The first day after the washout period and the last day of the intervention period, all of the participants will go to the collection place between 8:00-10:00 after at least 10 hours of fasting. Then, they will deliver a sample of faeces taken as recent to this moment as possible (in a stool collection tube introduced in an anaerobic plastic zip bag). Then they will have to spit into a 15 ml Falcon tube to obtain at least 3 ml of saliva.
After the delivery of the samples, anthropometric data of height, weight and waist circumference will be taken. In addition, blood pressure will be measured during relaxation in triplicate using a digital oscillometric device (Omron model M6 Comfort, Omron Corporation, Tokyo, Japan) and employing at least two readings.
By last, participants will be allocated one by one to a contiguous room where a sample of blood will be taken by a specialist belonging to an independent laboratory, who is also responsible for the blood analysis.
Primary outcome measure
1. Full serum count, erythrocyte sedimentation rate, c-reactive protein, sodium, potassium, chloride, bicarbonate, urea, creatinine, bilirubin, gamma-glutamyl transferase, total protein, albumin, calcium, phosphate, uric acid, random blood glucose, cholesterol, high-density lipoprotein, low-density lipoprotein and triglycerides; measured using a blood test at baseline and at the end of the control/intervention period
2. Blood pressure (mmHg), height (cm), weight (kg), waist diameter (cm) and hip circumference (cm) measured at baseline and at the end of the control/intervention period
Secondary outcome measures
1. Short-chain fatty acids (SCFA) and phenolic metabolites analysed in faecal samples by gas chromatography–mass spectrometry (GC-MS) and ultra-high performance liquid chromatography mass spectrometry (UHPLC–MS), respectively, according to previous laboratory procedures at baseline and at the end of the control/intervention period
2. Microbiota sequencing analysis of faecal samples following a bacteria metagenomic approach (Illumina technology) at baseline and at the end of the control/intervention period
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Participants have to present at least two of the following risk factors of metabolic syndrome:
1. Hypertension (systolic BP ≥130 mmHg or diastolic BP >85 mmHg)
2. Hypercholesterolemia (HDL colesterol <40 mg/dl in men and <50 mg/dl in women)
3. Hypertriglyceridemia (triglycerides >150 mg/dl)
4. Increased fasting plasma glucose (>100 mg/dl)
5. Increased waist circumference (>94 cm in men and >80 cm in women)
Target number of participants
Total final enrolment
Participant exclusion criteria
1. Serious cardiovascular disease
2. Antibiotic intake up to 3 months before the study
3. Endocrine and gastrointestinal disorders
4. Addiction to drugs or alcohol
5. Restrictive diets (vegetarians, vegans)
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Instituto de Investigación en Ciencias de la Alimentación
Nicolás Cabrera street, 9
Ministerio de Asuntos Económicos y Transformación Digital
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
1. Planned publication in a high-impact journal
2. Participants desiring to know the outcomes of the study will be informed individually by email
3. The protocol and the statistical analysis will be available when the results are published in a scientific journal
IPD sharing statement
The datasets generated during and/or analysed during the current study (serum blood analytics, anthropometrical data, blood pressure, faecal metabolites and sequencing data) are/will be available upon request from Diego Taladrid (email@example.com), Begoña Bartolomé (firstname.lastname@example.org), and M.Victoria Moreno-Arribas (email@example.com). Data were anonymized but participants desiring to know the outcomes of the study were informed individually of their corresponding data by email.
Intention to publish date
Participant level data
Available on request
Basic results (scientific)