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Trial registered on ANZCTR


Registration number
ACTRN12609000292279
Ethics application status
Approved
Date submitted
11/05/2009
Date registered
18/05/2009
Date last updated
18/05/2009
Type of registration
Retrospectively registered

Titles & IDs
Public title
The impact of dietary salt intake on arterial wall function and blood pressure in healthy subjects.
Scientific title
The impact of dietary sodium chloride intake on arterial wall function in normotensive subjects: a randomised controlled cross-over intervention study.
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 4537 0
Condition category
Condition code
Cardiovascular 4825 4825 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Following a 2 week run-in phase on a low sodium (60mmol/day) diet participants will be randomised to receive in a sequential fashion 3 interventions A: 500mls tomato juice with no added salt/day, B: 500mls tomato juice with 90mmol sodium per day or C: 500mls tomato juice plus 140 mmol sodium per day, each for 4 weeks followed by a 2 week wash out period on the low sodium diet alone between each intervention.
Individuals will remain on their low sodium diet for the duration of the study.
Intervention code [1] 4296 0
Lifestyle
Comparator / control treatment
Low dietary sodium (60mmol/day) intake plus 500 mls tomato juice with no added salt orally per day for 4 weeks.
Control group
Active

Outcomes
Primary outcome [1] 5687 0
Arterial wall function measured by pulse wave velocity
Timepoint [1] 5687 0
Baseline, week 1, week 2 and week 4
Secondary outcome [1] 241587 0
Blood pressure measured by sphygmomanometer
Timepoint [1] 241587 0
Baseline, week 1, week 2, week4.
Secondary outcome [2] 241588 0
Markers of plasma oxidative stress (highly sensitive-C reactive protein (hs-CRP), nitrate and nitrite concentrations, lipid peroxides, lipofuscin-like flurophores) using standard laboratory measurements.
Timepoint [2] 241588 0
Baseline, week 1, week 2, week 4
Secondary outcome [3] 241589 0
Plasma concentrations of Vasoactive hormones (renin, aldosterone, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), N terminal C-natriuretic peptide (CNP), insulin, endothelin 1) using standard laboratory measurements
Timepoint [3] 241589 0
baseline, week 1 week 2, week 4

Eligibility
Key inclusion criteria
Normotensive, blood pressure < 130/85
Minimum age
20 Years
Maximum age
65 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
smoking, body mass index > 30, history of cardiovascular disease, renal disease (estimated glomerular filtration rate (eGFR) <85 -[age-30]ml/min) diabetes

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The holder of the allocation schedule is 'off-site' and sends notification to pharmacy (sealed opaque envelopes). for the order of salt addition to tomato juice
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
computerised sequence generation by www.randomisation.com
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Three way cross-over design with each subject acting as their own control. 2 week run in phase on low dietary sodium (60mmol/day), then random allocation to differing sequence of intervention A (tomato juice no added salt) intervention B (tomato juice plus 90mmol sodium) intervention C (tomato juice plus 140mmol sodium) There was a 4 week wash out period (no tomato juice low sodium diet 60mmol/day) between each intervention.
Phase
Type of endpoint(s)
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment outside Australia
Country [1] 1704 0
New Zealand
State/province [1] 1704 0

Funding & Sponsors
Funding source category [1] 4940 0
Charities/Societies/Foundations
Name [1] 4940 0
National Heart Foundation of New Zealand
Address [1] 4940 0
National Heart Foundation of NZ
PO Box17-160 Greenlane
Auckland 1546
Country [1] 4940 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
Great King Street
PO Box 913
Dunedin 9015
Country
New Zealand
Secondary sponsor category [1] 4461 0
Hospital
Name [1] 4461 0
Dunedin Hospital
Address [1] 4461 0
Great King Street
Private Bag 1970
Dunedin 9015
Country [1] 4461 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 7040 0
Lower South Region Ethics Committee
Ethics committee address [1] 7040 0
229 Moray Place
PO Box 5849
Dunedin 9015
Ethics committee country [1] 7040 0
New Zealand
Date submitted for ethics approval [1] 7040 0
Approval date [1] 7040 0
06/06/2006
Ethics approval number [1] 7040 0
LRS/06/06/026

Summary
Brief summary
Epidemiological studies have demonstrated the association between dietary NaCl (sodium chloiride or salt) intake and hypertension and the risk of cardiovascular disease. Reduction in dietary NaCl intake lowers blood pressure significantly, with a subsequent reduction in cardiovascular events. Reducing dietary NaCl increases arterial compliance and reduces arterial stiffness in older people with systolic hypertension. Experimentally, NaCl affects arterial stiffness by altering vascular structure along with smooth muscle cell and endothelial cell function through a variety of mechanisms. There are only a limited number of studies which have examined the effects of dietary NaCl on arterial wall function in vivo in humans. These studies have focused predominantly on large artery compliance. This study proposes to examine the impact of low, normal and high dietary NaCl on arterial function in normal healthy volunteers. Arterial function can be measured non-invasively by pulse wave analysis, pulse wave velocity and markers of endothelial function. Using these different techniques collectively, we will be able to document the impact of dietary NaCl on arterial compliance in normotensive individuals. This will then allow for subsequent studies investigating the impact of dietary NaCl in at risk populations of hypertensive individuals and those with chronic kidney disease.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 29445 0
Address 29445 0
Country 29445 0
Phone 29445 0
Fax 29445 0
Email 29445 0
Contact person for public queries
Name 12692 0
Prof Rob Walker
Address 12692 0
Department of Medical & Surgical Sciences
Dunedin SChool of Medicine
PO Box 913 Dunedin 9015
Country 12692 0
New Zealand
Phone 12692 0
64 3 474 0999
Fax 12692 0
64 3 474 7641
Email 12692 0
rob.walker@otago.ac.nz
Contact person for scientific queries
Name 3620 0
Prof Rob Walker
Address 3620 0
Department of Medical & Surgical Sciences
Dunedin SChool of Medicine
PO Box 913 Dunedin 9015
Country 3620 0
New Zealand
Phone 3620 0
64 3 4740999
Fax 3620 0
64 3 4747641
Email 3620 0
rob.walker@otago.ac.nz

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary