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CompletedNCT05412654Updated Apr 4, 2024

Potassium Supplementation to Reduce Blood Pressure

An interventional study of High potassium water and Control low potassium water in Prehypertension, sponsored by Oxford Brookes University. Completed at 1 site in United Kingdom. Open to participants aged 20 Years to 64 Years. Per ClinicalTrials.gov, last updated 2024-04-04.

Sponsored by Oxford Brookes University · Not applicable, Interventional, and Treatment

Phase
Not applicable
Study type
Interventional
Enrollment
40
Allocation
Randomized
Ages
20 Years to 64 Years
Sex
All
01

Study summary

The aim of this study is to conduct a definitive trial to assess the efficacy of consuming 1L/day of water rich in potassium to reduce blood pressure in mild to moderately hypertensive adults. The objective is to assess the potential effect of the intervention on reducing systolic blood pressure. This study will comprise of a 4 week, double-blind, parallel randomised controlled trial. Participants will be adults with systolic blood pressure measurements of 130mmHg or greater. The intervention comprises advice to consume bottled water rich in potassium. The comparator will be regular bottled mineral water.This study will recruit 40 people with elevated systolic blood pressure (≥130mmHg) who are not regularly taking antihypertensive medication.

02

Conditions studied

  • Prehypertension

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Keywords

  • Potassium
  • Blood pressure
  • Systolic
  • Randomised
03

In context

Prehypertension

158 studies on the registry are indexed under Prehypertension; 21 are open to participants now.

This study's enrollment of 40 is below the median of 66 across 138 interventional studies indexed under Prehypertension.

Browse Prehypertension studies →

Lead sponsor

Oxford Brookes University is the lead sponsor of 35 studies on the registry; 6 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
20 Years to 64 Years
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Willing and able to provide
  • Between 20 to 64 years old
  • English speaking
  • Adults who are not receiving antihypertensive pharmacological treatment
  • Recent (within 6 months) and latest systolic blood pressure measurement ≥130mmHg and/or diastolic ≥85 mmHg
  • Have access to internet and equipment for video calling
  • Able to post samples and equipment to OxBCNH
  • Physically able to take own body measurements and blood pressure

Exclusion criteria

Exclusion Criteria:

  • Participation in another research study
  • Unable to read and understand the instructions provided in English
  • Unable to comply with experimental procedures or not follow testing safety guidelines
  • People with cardiovascular conditions: heart attack or stroke within the last 3 months, heart failure of grade II and more severe, or prolonged syndrome, angina, arrhythmia or atrial fibrillation.
  • Uncontrolled type 2 diabetes (> 9%)
  • Type 2 diabetes controlled using exogenous insulin
  • Previous or current diagnosis of diabetes complications such as nephropathy, retinopathy and neuropathy.
  • People with type 1 diabetes
  • Currently on any medication that may lead to hyperkalemia or fluid retention
  • Currently being assessed for diagnosis of hypertension (not receiving treatment for high blood pressure)
  • Already on clinician/HCP supervised diet or restricted diet
  • They are planning on going away from home (holiday or other) during the 4 week intervention period and will not be able to take water during this time.
  • Currently prescribed antihypertensive medications, or have been in the last 6 weeks
  • Chronic kidney disease stage 1 (G1A2 or G1A3), 2 (G2A2 or G2A3), 3a, 3b, 4 or 5 based on UKKA (we will ask whether participants have been diagnosed with kidney disease by a clinician based on this criteria)
  • They are planning to go on a diet or begin taking supplements containing potassium during the intervention
  • Pregnant women (including women suspected of being pregnant) and breast-feeding woman.
Terms in these criteria, in plain language(4)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

NYHA class (heart failure)

The New York Heart Association’s four classes of how much heart failure limits physical activity.

I
No limits: ordinary activity causes no undue tiredness or breathlessness.
II
Slight limits: comfortable at rest, ordinary activity causes symptoms.
III
Marked limits: comfortable at rest, less than ordinary activity causes symptoms.
IV
Symptoms even at rest; any activity makes them worse.

Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.

QT and QTc

On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.

The study may name a correction formula and a limit in milliseconds, often around 450–480.

HbA1c

A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.

05

Study design

Phase
Not applicable
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Participant, Outcomes assessor)
Enrollment
40 participants (actual)

Study arms

  • Experimental
    High potassium water

    All participants will be provided with bottled water for the duration of the 4 week intervention to consume 1L/day. The intervention group will receive high potassium water. Participants will be instructed to consume 1 bottle (500 mL) within 2 hours after waking up and 1 bottle (500 mL) within 2 hours before going to bed (total 1L/day). Participants will continue with the same diet and exercise patterns in their daily life similar to before participating in the study, for the whole length of the intervention.

    Dietary Supplement: High potassium water

  • Placebo comparator
    Low potassium control water

    All participants will be provided with bottled water for the duration of the 4 week intervention to consume 1L/day. The control group will receive regular bottled mineral water. Participants will be instructed to consume 1 bottle (500 mL) within 2 hours after waking up and 1 bottle (500 mL) within 2 hours before going to bed (total 1L/day). Participants will continue with the same diet and exercise patterns in their daily life similar to before participating in the study, for the whole length of the intervention.

    Dietary Supplement: Control low potassium water

Interventions

  • Dietary supplementHigh potassium water

    High potassium water Potassium 6.2 mg/100ml

  • Dietary supplementControl low potassium water

    Control water Potassium 0.2 mg/100ml

06

What researchers measure

Primary outcomes

  1. Seated home measured systolic blood pressure mm/Hg

    Blood pressure will me monitored by the participant at home, after detailed instruction are provided by trained researchers over Zoom. Measurements will be taken in duplicate, in the morning and again in the evening (4 times a day total) and the average values will be taken.

    Time frame: Blood pressure will be taken at three time points through out the 4 weeks.

Secondary outcomes

  1. Seated home measured diastolic blood pressure

    Blood pressure will me monitored by the participant at home, after detailed instruction are provided by trained researchers over Zoom. Measurements will be taken in duplicate, in the morning and again in the evening (4 times a day total) and the average values will be taken.

    Time frame: Blood pressure will be taken at three time points through out the 4 weeks

  2. Qualitative semi-structured, part open ended survey of acceptability of trial and reported barriers

    This survey will be designed by the researchers understand the participant experience of the intervention, in order to optimise any future study expansion. This will include things that worked well and those that did not work as well, during the trial (consumption of the water, convenience, appropriateness of outcome measures, burden on daily activities and lifestyle, etc.)

    Time frame: This survey will be administered on the final visit at week 4 of the trial.

07

Study locations

1 site
  • Oxford Brookes University
    Oxford, Oxfordshire ox30bp, United Kingdom
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Apr 4, 2024, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05412654
Lead sponsor
Oxford Brookes University
Collaborators
Suntory Beverage & Food Limited
Responsible party
Shelly Coe (Senior Lecturer in Nutrition, Oxford Brookes University) — Principal investigator
First posted
Jun 9, 2022
Start date
Jul 30, 2022
Primary completion
Dec 1, 2023
Completion
Dec 1, 2023
Last update
Apr 4, 2024

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Apr 2024. You cannot join it, but the record below documents what was studied.

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