Cardiovascular DiseaseNCT06740448
Investigating the Effects of Green Tea on Blood Viscosity
A study testing Green Tea in people with Cardiovascular Disease, run by University of Reading at 1 site in United Kingdom.
Trial summary
A diet high in flavonoids is becoming more established as beneficial to human health. Recent data suggest that the regular consumption of flavanols can reduce the numbers of deaths by cardiovascular disease at a population level. Read more about this study
- Who is it for?
- Ages 65 years and olderHealthy volunteers can take part
- Conditions the study is for
- Cardiovascular Disease
- What is being tested?
- Green Tea
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 35 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- Jan 2025to May 2025
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 65 years and older
- All sexes
- Healthy volunteers accepted
- Older adult
Who may be able to join
- Participants ages 65 years and older
- Non-smoker Participants with at least 2 'good' veins for giving blood
Who cannot join
- Participants under (BMI <18.5 kg/m2) or extremely over-nourished (BMI >30 kg/m2)
- Participants on prescription medication for CVD or regularly taking blood thinning drugs such as aspirin.
- Participants with a history of CVD or CVD in immediate family/ high resting blood pressure
- Participants with any food allergies/intolerances
- Participants with a history of metabolic diseases/ high resting blood glucose
- Participants with high resting levels of inflammatory markers (CRP)
- Participants on hormone replacement therapy
- Participants with abnormal red blood cell count or low haemoglobin stores
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Emily Waterfield, MSci contact
United Kingdom1 site
Hugh Sinclaire Unit of Human Nutrition, Departmeant of Food and Nutrition, University of Reading
Reading
Jeremy P E Spencer, PhD, +44 1183788724, j.p.e.spencer@reading.ac.uk
Jeremy P E Spencer, PhD
About this study
Official title: Investigating the Effects of Green Tea on Whole Blood Viscosity
A diet high in flavonoids is becoming more established as beneficial to human health. Recent data suggest that the regular consumption of flavanols can reduce the numbers of deaths by cardiovascular disease at a population level. The mechanisms for these reductions in deaths by cardiovascular disease are still debated and little is known about their impacts on factors affecting blood viscosity. The metabolism of flavanols is complex, with different metabolites being predominant in the blood at different time points. Therefore, in this study, we will investigate the effects of green tea, a well-known source of flavanols, on blood viscosity at different time points. This will be assessed in healthy individuals with no history of cardiovascular disease aged 65+ years old. Blood viscosity will be measured before, and 2hours and 8hours after the consumption of green tea.
Read the detailed description
Participants will first be screened via a questionnaire on RedCap. This will include a list of exclusion and inclusion criteria. Examples of what will be included are: must be a non-smoker, no history of CVD or CVD in immediate family, no history of metabolic diseases, no food allergies, or intolerances and not be on any medication for cardiovascular purposes (e.g. aspirin or blood pressure medication).
Before confirmation, a screening visit will be undertaken where checks for regular haematocrit, blood pressure, plasma triglycerides, blood glucose and inflammatory markers and BMI will be taken. This will involve a 4.5 ml blood sample. Additionally, the research nurse will assess the potential participant's veins, and participants who do not have 2 'good' veins for giving blood will be excluded from the trial.
Following recruitment, participants will be asked to follow a set of criteria for the 24 hours prior to participating in the study. This will include, following a low polyphenol diet and not consuming any over the counter medication, caffeine or alcohol for 24 hours prior to participating. Participants will also be asked to attend fasted for 12 hours. Participants will also be asked to not take part in any vigorous/aerobic exercise in the 24 hours leading up to the study.
Following recruitment, and on arrival, participants will be asked to confirm they have followed the requirements for the previous 24 hours and full informed consent will be obtained from the participant. Participants will complete a spot urine test to measure osmolality as a measure of hydration. Participants will be asked to sit in a rested position for 15 min prior to each blood sample. Blood pressure will then be measured followed by a blood sample (17.5ml). The blood sample will be passed through the viscometer to assess whole blood and plasma viscosity and part of the blood sample will be used to measure haematocrit, inflammatory markers and blood lipids. The participant will then be given 200 mL green tea. They will be asked to consume this within 15 minutes. The intervention will be provided in an opaque cup with a lid on and the participant will be asked not to remove the lid so that the contents is not revealed to them. This will be followed by a low flavonoid breakfast. The same blood sample and urine test will then be taken at 2 hours and 8 hours after the start of consuming the drink, and these will be processed in the same way. A low flavonoid meal will also be provided between the 2- and 8-hour blood sample. A second visit will involve the exact same protocol; however, the participants will be given hot water as a control condition.
On the first of two visits, the participant will be asked to fill out a food frequency questionnaire. The order of green tea/control visits will be randomised and counterbalanced. In the 12-hours leading up to the visit, participants will be asked to consume 500 mL of water (a bottle will be provided). Throughout the visit, participants will be provided with unlimited water to drink and the total volume that has been consumed between each blood sample throughout the study will be recorded. On the second visit, the participant will be asked to replicate this amount.
- Conditions
- Cardiovascular Disease
- Being tested
- Green Tea, Control (Hot Water)
- Keywords
- Flavanol, Green Tea, Blood Viscosity, Older Adults
- Medical subject headings
- Cardiovascular Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Green TeaDietary supplement
200 mL Green Tea
Control (Hot Water)Dietary supplement
200 mL hot water
| Study group | Role | What they receive |
|---|---|---|
| Green Tea | Experimental | 200 mL green tea on first visit Receives: Dietary Supplement: Green Tea; Dietary Supplement: Control (Hot Water) |
| Hot Water | Placebo comparator | 200 mL hot water on first visit Receives: Dietary Supplement: Green Tea; Dietary Supplement: Control (Hot Water) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Whole Blood Viscosity
Measured: Baseline to 2 hours and 8 hours
Secondary outcomes (3)
Plasma Viscosity
Measured: Baseline to 2 hours and 8 hours
Blood Triglycerides
Measured: Baseline to 2 hours and 8 hours
C-reactive protein
Measured: Baseline to 2 hours and 8 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Dec 2024
- Study startJan 2025 (estimated)
- Primary completionMay 2025 (estimated)
- Study completionMay 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cardiovascular DiseaseStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- A randomised, single blind, crossover design with a 3 week washout period between conditions investigating the acute effects (over 2 and 8 hours) of green tea on blood viscosity
- Masking
- Double blind
- Who is masked
- Investigator, Outcomes assessor
- Enrolment
- 35 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Reading
- Sponsor type
- University, hospital or other
- Collaborators
- Biotechnology and Biological Sciences Research Council, Royal Berkshire NHS Foundation Trust
- Responsible party
- Principal investigator, Jeremy Paul Edward Spencer, University of Reading
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06740448
- Sponsor's protocol ID
- UREC 24/22
- Status last verified
- Dec 2024
- First submitted
- 13 Dec 2024
- Last updated
- 27 Dec 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 27 Dec 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Effects of Green Tea on Whole Blood Viscosity
- ClinicalTrials.gov ID
- NCT06740448
- Acronym / sponsor ID
- UREC 24/22
- Conditions
- Cardiovascular Disease
- Keywords
- Flavanol, Green Tea, Blood Viscosity, Older Adults
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 35 participants (estimated)
- Lead sponsor
- University of ReadingUniversity, hospital or other
- Collaborators
- Biotechnology and Biological Sciences Research Council, Royal Berkshire NHS Foundation Trust
- Study start
- Jan 2025 (estimated)
- Primary completion
- May 2025 (estimated)
- Study completion
- May 2025 (estimated)
- First posted
- 18 Dec 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A diet high in flavonoids is becoming more established as beneficial to human health. Recent data suggest that the regular consumption of flavanols can reduce the numbers of deaths by cardiovascular disease at a population level. The mechanisms for these reductions in deaths by cardiovascular disease are still debated and little is known about their impacts on factors affecting blood viscosity. The metabolism of flavanols is complex, with different metabolites being predominant in the blood at different time points. Therefore, in this study, we will investigate the effects of green tea, a well-known source of flavanols, on blood viscosity at different time points. This will be assessed in healthy individuals with no history of cardiovascular disease aged 65+ years old. Blood viscosity will be measured before, and 2hours and 8hours after the consumption of green tea.
Detailed description
Participants will first be screened via a questionnaire on RedCap. This will include a list of exclusion and inclusion criteria. Examples of what will be included are: must be a non-smoker, no history of CVD or CVD in immediate family, no history of metabolic diseases, no food allergies, or intolerances and not be on any medication for cardiovascular purposes (e.g. aspirin or blood pressure medication).
Before confirmation, a screening visit will be undertaken where checks for regular haematocrit, blood pressure, plasma triglycerides, blood glucose and inflammatory markers and BMI will be taken. This will involve a 4.5 ml blood sample. Additionally, the research nurse will assess the potential participant's veins, and participants who do not have 2 'good' veins for giving blood will be excluded from the trial.
Following recruitment, participants will be asked to follow a set of criteria for the 24 hours prior to participating in the study. This will include, following a low polyphenol diet and not consuming any over the counter medication, caffeine or alcohol for 24 hours prior to participating. Participants will also be asked to attend fasted for 12 hours. Participants will also be asked to not take part in any vigorous/aerobic exercise in the 24 hours leading up to the study.
Following recruitment, and on arrival, participants will be asked to confirm they have followed the requirements for the previous 24 hours and full informed consent will be obtained from the participant. Participants will complete a spot urine test to measure osmolality as a measure of hydration. Participants will be asked to sit in a rested position for 15 min prior to each blood sample. Blood pressure will then be measured followed by a blood sample (17.5ml). The blood sample will be passed through the viscometer to assess whole blood and plasma viscosity and part of the blood sample will be used to measure haematocrit, inflammatory markers and blood lipids. The participant will then be given 200 mL green tea. They will be asked to consume this within 15 minutes. The intervention will be provided in an opaque cup with a lid on and the participant will be asked not to remove the lid so that the contents is not revealed to them. This will be followed by a low flavonoid breakfast. The same blood sample and urine test will then be taken at 2 hours and 8 hours after the start of consuming the drink, and these will be processed in the same way. A low flavonoid meal will also be provided between the 2- and 8-hour blood sample. A second visit will involve the exact same protocol; however, the participants will be given hot water as a control condition.
On the first of two visits, the participant will be asked to fill out a food frequency questionnaire. The order of green tea/control visits will be randomised and counterbalanced. In the 12-hours leading up to the visit, participants will be asked to consume 500 mL of water (a bottle will be provided). Throughout the visit, participants will be provided with unlimited water to drink and the total volume that has been consumed between each blood sample throughout the study will be recorded. On the second visit, the participant will be asked to replicate this amount.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- A randomised, single blind, crossover design with a 3 week washout period between conditions investigating the acute effects (over 2 and 8 hours) of green tea on blood viscosity
| Arm | Type | Receives |
|---|---|---|
| Green Tea | Experimental | Dietary Supplement: Green Tea, Dietary Supplement: Control (Hot Water)200 mL green tea on first visit |
| Hot Water | Placebo comparator | Dietary Supplement: Green Tea, Dietary Supplement: Control (Hot Water)200 mL hot water on first visit |
Who may qualify
- Ages
- 65 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Older adult
Key inclusion criteria (2 listed)
- Participants ages 65 years and older
- Non-smoker Participants with at least 2 'good' veins for giving blood
Key exclusion criteria (8 listed)
- Participants under (BMI <18.5 kg/m2) or extremely over-nourished (BMI >30 kg/m2)
- Participants on prescription medication for CVD or regularly taking blood thinning drugs such as aspirin.
- Participants with a history of CVD or CVD in immediate family/ high resting blood pressure
- Participants with any food allergies/intolerances
- Participants with a history of metabolic diseases/ high resting blood glucose
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Green Tea200 mL Green Tea | Dietary supplement | Green Tea, Hot Water |
| Control (Hot Water)200 mL hot water | Dietary supplement | Green Tea, Hot Water |
Primary outcome
Whole Blood Viscosity
Time frame: Baseline to 2 hours and 8 hours
3 secondary outcomes
Plasma Viscosity
Time frame: Baseline to 2 hours and 8 hours
Blood Triglycerides
Time frame: Baseline to 2 hours and 8 hours
C-reactive protein
Time frame: Baseline to 2 hours and 8 hours
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 Dec 2024.
- Individual participant dataSharing planned: Yes
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Emily Waterfield, MSci contact
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Green Tea in people with Cardiovascular Disease, run by University of Reading at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 27 Dec 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Jeremy P E Spencer, PhD (+44 (0) 118 378 8724, j.p.e.spencer@reading.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Whole Blood Viscosity (time frame: Baseline to 2 hours and 8 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 Dec 2024.