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Trial registered on ANZCTR


Registration number
ACTRN12609000321246
Ethics application status
Approved
Date submitted
17/04/2009
Date registered
21/05/2009
Date last updated
5/07/2012
Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of reducing dietary salt intake on the way blood vessels work
Scientific title
Effects of modification of dietary salt intake on endothelial function in human subjects with and without the metabolic syndrome
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Metabolic syndrome 4747 0
Endothelial function 4748 0
Condition category
Condition code
Cardiovascular 4917 4917 0 0
Diseases of the vasculature and circulation including the lymphatic system
Metabolic and Endocrine 237083 237083 0 0
Metabolic disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
In a randomised cross-over fashion, participants will follow a reduced salt diet (6g salt/day, 100mmol Na/day) for 6 weeks and a usual salt diet (10g salt/day, 166 Na/day) for 6 weeks. The higher salt diet will be achieved by the addition of 6 tablets a day containing a small amount (10mmol sodium each) to the reduced salt diet. There will be no wash-out period between interventions. Participants will attend 2 half hour education sessions with the dietitian at Visit 1 & Visit 2 during the first week of the study and will attend another 2 half hour education sessions at Visit 3 & Visit 4 at week 6. Dietitian instruction will cover how to follow a reduced salt diet and participants will receive extensive education about the salt content of foods, label reading and example meal recipes to aid compliance with the diet. Compliance with diets will be measured by 24hour urinary sodium excretion at baseline, day 2, week 6, 2 days after week six and week 12. Trial managers will also collect tablets at the end of the normal salt diet periods as another measure of compliance.
Intervention code [1] 4378 0
Lifestyle
Comparator / control treatment
This is a cross over study so each participant acts as their own control
Control group
Active

Outcomes
Primary outcome [1] 5762 0
Change in endothelial function as measured by flow-mediated dilatation (FMD)
Timepoint [1] 5762 0
FMD is measured at each of the following time points: Baseline (start of the intervention), 2 days after baseline, week6, 2 days after week 6 and at week 12
Secondary outcome [1] 241715 0
Vascular compliance measured by pulse wave velocity (PWV) and augmentation index (AI)
Timepoint [1] 241715 0
PWV & AI is measured at each of the following time points: Baseline (start of the intervention), 2 days after baseline, week6, 2 days after week 6 and at week 12
Secondary outcome [2] 241716 0
Fasting venous blood samples will be used to measure plasma nitrate/nitrites which will be analysed using a colorimetric assay and plasma asymmetric dimethylarginine (ADMA) will be measured using high performance liquid chromatography (HPLC)
Timepoint [2] 241716 0
Nitric oxide bioavilabitly will be measured at Baseline (start of the intervention), 2 days after baseline, week6, 2 days after week 6 and at week 12
Secondary outcome [3] 241717 0
Vasoactive hormones including renin and aldosterone will be measured from blood samples
Timepoint [3] 241717 0
Vasoactive hormones will be measured at Baseline (start of the intervention), 2 days after baseline, week6, 2 days after week 6 and at week 12
Secondary outcome [4] 241718 0
Blood samples will be taken to measure the concentrations of (i) soluble adhesion molecules which are primarily derived from the endothelium, Inter-Cellular Adhesion Molecule 1 (ICAM-1), Vascular cell adhesion molecule 1 (VCAM-1), E & P-selectin and endothelin-1 (ET-1), (ii) inflammatory markers, (iii) molecules involved in the fibrinolytic pathway; tissue plasminogen activator (tPA) & Plasminogen activator inhibitor-1 (PAI-1) released from the endothelium
Timepoint [4] 241718 0
Blood markers of endothelial function will be measured at each of the following time points: Baseline (start of the intervention), 2 days after baseline, week6, 2 days after week 6 and at week 12

Eligibility
Key inclusion criteria
Weight stable individuals with systolic blood pressure between 120-139mmHg and diastolic blood pressure between 80-89mmHg. Those with and without the metabolic syndrome (defined as waist circumference >94cm for men and >80cm for women plus two of the following: fasting triglycerides (TG) = to or > 1.7mmol/L, high density lipoprotein (HDL) cholesterol<1.03 (men) or 1.29 (women), fasting glucose 5.6-6.9mmol/L) will be eligible to participate in the study.
Minimum age
40 Years
Maximum age
70 Years
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Previous cardiovascular disease, treated hypertension, significant weight loss (>5% body weight) in the previous 6months, use of non-steroidal anti-inflammatory drugs, known metabolic disease such as liver or kidney disease

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation of treatment order will be done by a third person independant to the study. Subjects will be provided with salth tablets for the normal salt diet period. There is no placebo, therefore participants will not be blinded to the salt intervention.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation sequence will be generated using Clinstat software
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
The participants will not be blinded to diet intervention as they are to be educated about how to follow a reduced salt diet. Participants will be given salt tablets for the normal salt intervention so therefore will not be blinded to the intervention. Persons performing outcome measures will be blinded to treatment allocation
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
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 in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 4802 0
Government body
Name [1] 4802 0
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Address [1] 4802 0
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition PO Box 10041 Adelaide BC SA 5000
Country [1] 4802 0
Australia
Primary sponsor type
Government body
Name
CSIRO Human Nutrition
Address
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition PO Box 10041 Adelaide BC SA 5000
Country
Australia
Secondary sponsor category [1] 4332 0
None
Name [1] 4332 0
Address [1] 4332 0
Country [1] 4332 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 6846 0
CSIRO Human Research Ethics Committee
Ethics committee address [1] 6846 0
CSIRO Human Nutrition
Gate 13 Kintore Avenue
Adelaide SA 5000
Ethics committee country [1] 6846 0
Australia
Date submitted for ethics approval [1] 6846 0
Approval date [1] 6846 0
23/03/2009
Ethics approval number [1] 6846 0
09/09

Summary
Brief summary
Cardiovascular disease is a major disease burden, accounting for over 45% of all deaths. Obesity, and its consequences, the metabolic syndrome and type 2 diabetes increase the risk of heart disease potentially leading to early death or disability. Reducing dietary salt is a neglected, valuable intervention with the potential to reduce cardiovascular events. The primary aim of the study is to determine, in a 12 week study the effect of a reduced salt diet (6g salt/day, 100mmol Na/day) compared to a usual salt diet (10g salt/day, 166mmolNa/day) on blood vessel function, as assessed by the ultrasound measurement of blood flow in overweight people with and without the metabolic syndrome who are at increased risk of heart disease. The expected outcomes are that a lower salt intake will have a beneficial effect on the way blood vessels work and reduce an individual’s risk for heart attack. The results will support moves to reduce salt in the food supply thereby reducing heart disease risk in the general community as well as in individuals at higher risk. Data from this study will provided a very strong incentive to reduce dietary salt.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 29500 0
Address 29500 0
Country 29500 0
Phone 29500 0
Fax 29500 0
Email 29500 0
Contact person for public queries
Name 12747 0
Dr Jennifer Keogh
Address 12747 0
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition PO Box 10041 Adelaide BC SA 5000
Country 12747 0
Australia
Phone 12747 0
+61 8 8303 8907
Fax 12747 0
+61 8 8303 8899
Email 12747 0
jennifer.keogh@csiro.au
Contact person for scientific queries
Name 3675 0
Dr Jennifer Keogh
Address 3675 0
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition PO Box 10041 Adelaide BC SA 5000
Country 3675 0
Australia
Phone 3675 0
+61 8 8303 8907
Fax 3675 0
+61 8 8303 8899
Email 3675 0
jennifer.keogh@csiro.au

No information has been provided regarding IPD availability
Summary results
No Results