Acute effects of hibiscus sabdariffa on cardiometabolic markers and cognitive function
| ISRCTN | ISRCTN14881129 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN14881129 |
- Submission date
- 07/06/2024
- Registration date
- 20/06/2024
- Last edited
- 03/03/2025
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Circulatory System
Plain English summary of protocol
Background and study aims
Hibiscus is a plant from the Malvaceae family which contains polyphenols, predominantly anthocyanins. Evidence suggests that the consumption of hibiscus has a beneficial effect on reducing blood pressure and in modulating lipids. However, despite evidence that other anthocyanin-containing plants can have a favourable impact on cognitive function, there is no evidence thus far which outlines any potential benefit of hibiscus consumption on cognitive function in human clinical trials. The pilot study aims to examine the effect of anthocyanin-rich hibiscus sabdariffa tea on blood pressure, glucose and cognitive function in metabolically challenged individuals.
Who can participate?
Adult participants (age 18-55 years old) who have at least one risk factor for cardiovascular disease such as, but not limited to, high blood pressure/mild hypertension (SBP between 130-159 and DBP >80-99 mmHg), overweight (>27 kg/m2 ) but not morbidly obese (BMI >35 kg/m2 ). Participants will not be taking any medication.
What does the study involve?
Participants will be randomly allocated to consume either a hibiscus concentrate or a placebo (alongside a small breakfast consisting of two slices of toast and butter) on two separate occasions using counterbalancing with at least a 5-day washout between study visits. During each visit, participants will complete a baseline set of measurements, including blood pressure, wearing a continuous glucose monitor (CGM) and cognitive function. Participants will then consume the test beverage. Blood pressure will be measured every 10 minutes. The CGM measures interstitial glucose every 15 minutes and the same monitor will be worn across both study visits. Cognitive function is assessed again at 90 minutes post-consumption of the test drink and meal.
What are the risks and benefits of taking part?
There are no direct benefits for participants taking part, however, participants are compensated for their time attending the study. There are small risks associated with wearing the CGM such as minor bruising.
Where will the study run from?
The Human Appetite Research Unit, University of Leeds
When is the study starting and how long will it run for?
November 2023 to March 2024
Who is funding the study?
Lucy Ellis is supported by the Emma and Leslie Reid Scholarship Fund from the University of Leeds. The Hibiscus concentrate was kindly donated by Ibis Organics.
Who is the main contact?
Prof Louise Dye, l.dye@leeds.ac.uk
Contact information
Scientific, Principal Investigator
School of Food Science and Nutrition and School of Psychology
University of Leeds
Leeds
LS29JT
United Kingdom
 ORCID ID |
0000-0002-2331-4227 |
|---|---|
| Phone | +44 (0)113 343 7000 |
| l.dye@leeds.ac.uk |
Public
School of Psychology
University of Leeds
Leeds
LS29JT
United Kingdom
| ORCID ID |
0000-0002-0750-7248 |
|---|---|
| Phone | +44 (0)113 343 7000 |
| fs15lre@leeds.ac.uk |
Scientific
School of Food Science and Nutrition
University of Leeds
Leeds
LS29JT
United Kingdom
| ORCID ID |
0000-0001-6705-5709 |
|---|---|
| Phone | +44 (0)113 343 7000 |
| c.bosch@leeds.ac.uk |
Study information
| Study design | Single-centre randomized single-blind placebo-controlled crossover study |
|---|---|
| Primary study design | Interventional |
| Secondary study design | Randomised cross over trial |
| Study setting(s) | University/medical school/dental school |
| Study type | Efficacy |
| Participant information sheet | 45588_PIS.pdf |
| Scientific title | A randomized, single-blind, placebo-controlled study assessing the acute effects of hibiscus sabdariffa on cardiometabolic markers and cognitive function in metabolically challenged individuals |
| Study objectives | Hibiscus sabdariffa (hibiscus) is an anthocyanin-containing plant and currently, there are no human studies which assess cognitive effects after ingesting hibiscus. However, there are multiple RCTs which assess the cognitive-enhancing effects of anthocyanins. The main hypothesis is that consumption of hibiscus will significantly lower blood pressure (both systolic and diastolic) in a population of participants with high blood pressure. Additionally, the second hypothesis of this study is that hibiscus consumption will improve at least one outcome from the cognitive test battery chosen compared to a placebo drink. |
| Ethics approval(s) |
Approved 02/01/2024, The School of Psychology Research Ethics Committee (University of Leeds, Leeds, LS29JT, United Kingdom; +44 (0)113 2431751; psyc-ethicssubmissions@leeds.ac.uk), ref: PSCETHS-808 |
| Health condition(s) or problem(s) studied | Reduction of blood pressure |
| Intervention | The study is conducted using a counterbalanced crossover trial method, with each participant acting as their own control. Participants will be randomised to intervention order in a counterbalanced method using "visual basic for applications" coding in Excel. The same coding applies to counterbalancing each form of the cognitive tests between participants, sessions and visits as a method to minimise practice effects. Participants will attend two separate study visits with at least a 5-day washout between each visit. After completing baseline measurements, participants will consume either a hibiscus concentrate containing 260 mg anthocyanins or a placebo drink containing 0 mg anthocyanins, alongside a high carbohydrate breakfast on each study visit. Blood pressure, blood glucose and cognitive function are measured across a 2.5-hour postprandial period. |
| Intervention type | Other |
| Primary outcome measure | Blood pressure measured using an automatic blood pressure cuff (Omron) at baseline, and every 20 minutes after consumption of the drink and test meal for a 2 ½ hour postprandial period |
| Secondary outcome measures | 1. Interstitial glucose measured using a Continuous Glucose Monitor (Freestyle Libre, Abbott) every 15 minutes. 2. Cognitive function (verbal memory, executive function, pattern separation) measured using a Visual Verbal learning test, Tower of Hanoi and Pattern separation at baseline and then 90 minutes after the consumption of the drink |
| Overall study start date | 01/11/2023 |
| Completion date | 30/03/2024 |
Eligibility
| Participant type(s) | Patient |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Upper age limit | 56 Years |
| Sex | Both |
| Target number of participants | 20 |
| Total final enrolment | 20 |
| Key inclusion criteria | 1. Age 18-56 2. BMI more than 27kg/m2 but less than35kg/m2 3. Male and female, local to the Leeds area 4. Presence of high blood pressure 5. Sufficient knowledge and understanding of the English language (preferably first language) |
| Key exclusion criteria | 1. For women – pregnancy, lactation, perimenopause/menopause 2. Food allergy or intolerance to any of the study foods 3. Medical conditions – clinical depression, thyroid diseases, hypertension, type 1 or type 2 diabetes, or blood diseases 4. Using any medication for hypertension or cholesterol-lowering sterols 5. Recent blood donation (<3 months) 6. Participation in simultaneous studies |
| Date of first enrolment | 05/01/2024 |
| Date of final enrolment | 15/03/2024 |
Locations
Countries of recruitment
- England
- United Kingdom
Study participating centre
Leeds
LS29JT
United Kingdom
Sponsor information
University/education
Woodhouse Lane
Leeds
LS29JT
England
United Kingdom
| Phone | +44 (0)113 3435753 |
|---|---|
| psyc-enquiries@leeds.ac.uk | |
| Website | https://leeds.ac.uk |
"ROR" |
https://ror.org/024mrxd33 |
Funders
Funder type
University/education
Private sector organisation / Universities (academic only)
- Location
- United Kingdom
Results and Publications
| Intention to publish date | 30/06/2024 |
|---|---|
| Individual participant data (IPD) Intention to share | No |
| IPD sharing plan summary | Data sharing statement to be made available at a later date |
| Publication and dissemination plan | Planned publication in a peer-reviewed journal |
| IPD sharing plan | The data-sharing plans for the current study are unknown and will be made available at a later date |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Participant information sheet | 17/06/2024 | No | Yes | ||
| Statistical Analysis Plan | 17/06/2024 | No | No | ||
| Results article | 26/02/2025 | 03/03/2025 | Yes | No |
Additional files
Editorial Notes
03/03/2025: Publication reference added.
10/06/2024: Study's existence confirmed by The School of Psychology Research Ethics Committee, University of Leeds.
