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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
The role of gut pH in blood pressure regulation
Scientific title
The role of gut pH in blood pressure regulation of untreated hypertensives and healthy controls
Secondary ID [1] 300628 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 316398 0
Condition category
Condition code
Cardiovascular 314665 314665 0 0

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
The overall aim of the study is to determine the contribution of gut pH to blood pressure regulation via changes in inflammation. We will be doing this by comparing the gut pH of healthy controls to hypertensive patients, through the use of Smart Pill and Atmo Gas Capsules. These two pills measure gut pH and gases in real time as they travel through the length of the gastrointestinal tract.

Participants will also provide faecal samples to determine the associated gut microbiome and production of gut metabolites, as well as blood samples to determine associated immune cells associated with hypertension.

Participants will come to the study site (The Alfred Centre) for 2 visits. The first visit is for approximately 1 hour, where they will swallow both the Smart Pill/Gas capsule and given education on how to use/troubleshoot the device while it is in their system. They will be provided with a food diary and explained by a dietitian (study coordinator) on how to complete this food diary appropriately for the study. They will also be provided with patient diaries for the pills, to monitor bowel actions and symptoms for the duration that the pills are in their gastrointestinal tract. The food diary and patient diaries will be completed at home. Participants will be provided with a faecal sample kit and given explanation as to how to appropriately collect and store a faecal sample. A blood sample of ~20ml will be taken from participants on this visit. Participants will be given a 24hr blood pressure monitor to wear which takes blood pressure readings every 15-30 mins for the 24hr period.

On the second visit, participants will return the receivers that are supplied with the pills, as well as completed patient diaries and faecal sample. This visit will go for approximately 20-30mins.
Intervention code [1] 316954 0
Not applicable
Comparator / control treatment
Healthy controls will be used to compare all of the above methods of testing. Smart Pills, Atmo Gas Capsules, 24hr blood pressure monitor, faecal and blood sample data will be obtained from healthy controls.
Control group

Primary outcome [1] 322990 0
Gut pH as assessed by a Smart Pill
Timepoint [1] 322990 0
1-5 days post ingestion of pills.
Primary outcome [2] 323061 0
Blood pressure as assessed by a 24hr ambulatory blood pressure monitor
Timepoint [2] 323061 0
24 hours after assessment
Primary outcome [3] 323062 0
Arterial stiffness as measured by sphygmomanometer
Timepoint [3] 323062 0
At time of assessment
Secondary outcome [1] 380439 0
Plasma short chain fatty acids measured using gas chromatography
Timepoint [1] 380439 0
At the baseline visit/within 24-48 hours of the baseline visit.
Secondary outcome [2] 380632 0
Faecal short chain fatty acids measured using gas chromatography
Timepoint [2] 380632 0
At the baseline visit/within 24-48 hours of baseline visit

Key inclusion criteria
• 18-70 years of age
• BMI 18.5-30
• Either sex
• For hypertensive patients: Hypertension will be defined according to the Australian Heart Foundation guidelines using automated office blood pressure where BP is greater than or equal to 140/90 mmHg and 24h ambulatory blood pressure monitoring (AMBP) is greater than or equal to 130/80. Masked hypertensive patients will be included in the hypertensive group (office BP less than or equal to 140/90 mmHg but AMBP is greater than or equal to 130/80) and white coat hypertensives will be included as controls (office BP is greater than or equal to 140/90 mmHg but AMBP is less than or equal to 130/80).
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
• Use of anti-hypertensive medication
• Recent use of antibiotics (<3 months)
• Presence of type 1 or type 2 diabetes
• Pregnant women
• Presence gastrointestinal diseases (including inflammatory bowel disease, celiac disease, chronic pancreatitis or other malabsorption disorder).

Study design
Natural history
Convenience sample
Statistical methods / analysis
We will use step-wise multiple linear or logistic regression models adjusted for clinical variables as independent parameters in SPSS.

Primary endpoints: higher pH level being associated with higher blood pressure and pulse wave velocity (analysed as categorical and continuous variable).
Secondary endpoints: levels of gut pH associated with levels of SCFAs, gut microbiome and inflammatory markers.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 29438 0
3004 - Melbourne

Funding & Sponsors
Funding source category [1] 305051 0
Name [1] 305051 0
The Heart Foundation
Address [1] 305051 0
2/850 Collins St, Melbourne VIC 3008
Country [1] 305051 0
Primary sponsor type
Francine Marques
25 Rainforest Walk, Clayton VIC 3800, Monash University
Country: Australia
Secondary sponsor category [1] 305416 0
Name [1] 305416 0
Monash University
Address [1] 305416 0
Monash University
Victoria 3800
Country [1] 305416 0

Ethics approval
Ethics application status
Ethics committee name [1] 305439 0
Monash University Human Research Ethics Committee
Ethics committee address [1] 305439 0
Monash University Human Research Ethics Committee (MUHREC)
Room 111, Chancellery Building D,
26 Sports Walk, Clayton Campus
Research Office
Monash University VIC 3800
Ethics committee country [1] 305439 0
Date submitted for ethics approval [1] 305439 0
Approval date [1] 305439 0
Ethics approval number [1] 305439 0

Brief summary
High blood pressure is highly prevalent in Australia and is known as a 'silent disease' as it usually has no symptoms until it might be too late. In recent years, there has been increasing evidence that the gut microbiome plays a role in hypertension. The gut microbiome comprises the millions of tiny microorganisms that live in our gut, and can be manipulated through the diet.

We have exciting research in our lab that suggests this relationship between gut pH and blood pressure is regulated via changes in inflammation. pH is a measure of acidity from 1-14. The lower the pH, the more acidic that substance is. The higher the pH, the more alkaline and, therefore, less acidic that substance is. We believe that a lower pH in the gut, produced from the substances our gut microbes release, is associated with better control of blood pressure, and that hypertensive patients may have a higher pH than those subjects without high blood pressure. There is no research in humans that have looked at the pH of hypertensive patients specifically. The SmartPill Motility capsule is a device that measures in pH in real time, as the pill travels through the gastrointestinal tract. The Atmo Gas capsule is a device that measures gases, as well as acidic substances as they are absorbed along the gastrointestinal tract. Both of these pills will be utilised in this study.
The purpose of this research is to determine the gut pH of hypertensive patients.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 100390 0
Dr Francine Marques
Address 100390 0
25 Rainforest Walk, Clayton VIC 3800, Monash University
Country: Australia
Country 100390 0
Phone 100390 0
+61 0399056958
Fax 100390 0
Email 100390 0
Contact person for public queries
Name 100391 0
Dr Francine Marques
Address 100391 0
25 Rainforest Walk, Clayton VIC 3800, Monash University
Country: Australia
Country 100391 0
Phone 100391 0
+61 0399056958
Fax 100391 0
Email 100391 0
Contact person for scientific queries
Name 100392 0
Dr Francine Marques
Address 100392 0
25 Rainforest Walk, Clayton VIC 3800, Monash University
Country: Australia
Country 100392 0
Phone 100392 0
+61 0399056958
Fax 100392 0
Email 100392 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
What supporting documents are/will be available?
Study protocol
Informed consent form
Ethical approval
How or where can supporting documents be obtained?
Type [1] 7048 0
Study protocol
Citation [1] 7048 0
Link [1] 7048 0
Email [1] 7048 0
Other [1] 7048 0
Type [2] 7049 0
Ethical approval
Citation [2] 7049 0
Link [2] 7049 0
Email [2] 7049 0
Other [2] 7049 0
This has not been approved yet, however will provide once it has been approved.
Attachment [2] 7049 0
Type [3] 7050 0
Informed consent form
Citation [3] 7050 0
Link [3] 7050 0
Email [3] 7050 0
Other [3] 7050 0
Summary results
No Results