COVID-19 studies are our top priority. For all other trials, there is a 4-week delay in processing a trial submitted/resubmitted to the ANZCTR and additional delays for updates of registered trials. We appreciate your patience.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR


Registration number
ACTRN12620000966998
Ethics application status
Approved
Date submitted
16/07/2020
Date registered
28/09/2020
Date last updated
28/09/2020
Date data sharing statement initially provided
28/09/2020
Type of registration
Prospectively registered

Titles & IDs
Public title
Measuring added salt in the diet of healthy adults in New Zealand
Scientific title
The use of lithium-tagged salt to estimate discretionary salt use in the diet of healthy adults in New Zealand
Secondary ID [1] 301272 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Discretionary salt intake 317451 0
Condition category
Condition code
Diet and Nutrition 315549 315549 0 0
Other diet and nutrition disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
1. The lithium-tagged salt is produced in our food chemistry lab by combining lithium carbonate and sodium chloride. The final lithium content in the salt will be 250 micromol lithium/g salt (equivalent to 1.735g lithium/kg salt).

2. Participants will have ad libitum use of lithium-tagged salt for 7 days. Two 24-hour urine samples will be collected after 5-7 days of salt replacement. An increase in lithium in the urine will occur when participants replace usual salt intake with lithium-tagged salt.





Intervention code [1] 317577 0
Behaviour
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 323791 0
Mean sodium intake will be assessed by measuring sodium concentration in a 24-hour urine sample (this is the gold standard method of assessing sodium intake).
Timepoint [1] 323791 0
Between days 5 and 7 after lithium-tagged salt replacement, two 24-hour urine samples (one weekday and one weekend) will be collected.
Primary outcome [2] 325235 0
Discretionary intake of sodium will be assessed by measuring the difference in lithium excreted in 24-hour urine between baseline (i.e. usual salt use) and intervention (i.e. use of lithium-tagged salt).
Timepoint [2] 325235 0
Between days 5 and 7 after lithium-tagged salt replacement, two 24-hour urine samples (one weekday and one weekend) will be collected.
Secondary outcome [1] 382896 0
Mean iodine intake will be assessed by measuring iodine excreted in 24-hour urine.
Timepoint [1] 382896 0
Between days 5 and 7 after lithium-tagged salt replacement, two 24-hour urine samples (one weekday and one weekend) will be collected.
Secondary outcome [2] 385550 0
% sodium intake derived from natural sources
Timepoint [2] 385550 0
A day after each of the 24 hour urine samples are collected, a 24-hour dietary recall will take place (i.e. this will correspond to the day of 24 hour urine collection). Sodium intakes from sources can then be identified using the 24-hour recall..
Secondary outcome [3] 387286 0
% sodium intake derived from processed foods
Timepoint [3] 387286 0
A day after each of the 24 hour urine samples are collected, a 24-hour dietary recall will take place (i.e. this will correspond to the day of 24 hour urine collection). Sodium intakes from sources can then be identified using the 24-hour recall..
Secondary outcome [4] 387287 0
% sodium intake derived from discretionary sources
Timepoint [4] 387287 0
A day after each of the 24 hour urine samples are collected, a 24-hour dietary recall will take place (i.e. this will correspond to the day of 24 hour urine collection). Sodium intakes from sources can then be identified using the 24-hour recall..

Eligibility
Key inclusion criteria
Apparently healthy adults aged 18-40 years, use salt in cooking and/or at the table, prepare and eat meals prepared in their own home.
Minimum age
18 Years
Maximum age
40 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Taking diuretics or lithium; taking dietary supplements containing iodine; pregnant or breastfeeding; diagnosed renal or heart disease; children under 18 years old in the household

Study design
Purpose of the study
Prevention
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Who is / are masked / blinded?



Intervention assignment
Other design features
Phase
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Based on previous studies, approximately 15% of total sodium intake is derived from discretionary salt, and the population size of adults ages 18 to 40 in New Zealand is 1072887. Therefore, a sample size of 97 participants is needed to determine the mean proportion of dietary sodium from added salt with a 95% precision level of ±10%. With an attrition rate of 15%, we will require a total sample size of 116 participants.

Using Stata statistical software, data will be checked for normality, and reported as mean, standard deviation, 95% confidence interval, percentiles of dietary sodium (in grams), and % of sodium derived from natural, processed foods and discretionary salt. If salt intake is iodised, an estimation of the % of total iodine intake derived from added salt will also be determined.

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 outside Australia
Country [1] 22559 0
New Zealand
State/province [1] 22559 0
Dunedin

Funding & Sponsors
Funding source category [1] 305718 0
University
Name [1] 305718 0
University of Otago
Address [1] 305718 0
UNIVERSITY OF OTAGO, Dunedin • PO BOX 56, Dunedin 9054, NEW ZEALAND
Country [1] 305718 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
UNIVERSITY OF OTAGO, Dunedin • PO BOX 56, Dunedin 9054, NEW ZEALAND
Country
New Zealand
Secondary sponsor category [1] 306141 0
Government body
Name [1] 306141 0
Ministries of Primary Industries
Address [1] 306141 0
Ministry for Primary Industries - Manatu Ahu Matua | TSB Building 147 Lambton Quay | PO Box 2526 | Wellington | New Zealand
Country [1] 306141 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 305994 0
UNIVERSITY OF OTAGO HUMAN ETHICS COMMITTEE
Ethics committee address [1] 305994 0
90 St David's Street, North Dunedin 9016, Dunedin, New Zealand
Ethics committee country [1] 305994 0
New Zealand
Date submitted for ethics approval [1] 305994 0
02/12/2019
Approval date [1] 305994 0
23/01/2020
Ethics approval number [1] 305994 0
19/168

Summary
Brief summary
Most sodium in the diet comes from the salt added to processed foods, such as bread. Added salt, used at the table or in cooking, also contributes to the amount of sodium and, if it is iodised salt, to iodine that people eat. The aim of this project is to measure the amount of added salt eaten by adults in New Zealand. This is done so by replacing lithium-tagged salt with the salt used in cooking at home and salt added at the table. Lithium acts as a tracer in the salt to differentiate between discretionary salt intake and other sodium sources. This information will help us make recommendations about the use of salt including iodised salt in the New Zealand diet.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 102346 0
Prof Sheila Skeaff
Address 102346 0
UNIVERSITY OF OTAGO, Dunedin • PO BOX 56, Dunedin 9054, NEW ZEALAND
Country 102346 0
New Zealand
Phone 102346 0
+6434797944
Fax 102346 0
Email 102346 0
sheila.skeaff@otago.ac.nz
Contact person for public queries
Name 102347 0
Prof Sheila Skeaff
Address 102347 0
UNIVERSITY OF OTAGO, Dunedin • PO BOX 56, Dunedin 9054, NEW ZEALAND
Country 102347 0
New Zealand
Phone 102347 0
+6434797944
Fax 102347 0
Email 102347 0
sheila.skeaff@otago.ac.nz
Contact person for scientific queries
Name 102348 0
Prof Sheila Skeaff
Address 102348 0
UNIVERSITY OF OTAGO, Dunedin • PO BOX 56, Dunedin 9054, NEW ZEALAND
Country 102348 0
New Zealand
Phone 102348 0
+6434797944
Fax 102348 0
Email 102348 0
sheila.skeaff@otago.ac.nz

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
Individual participant data that underlie the results reported in this article, after deidentification (text, tables, figures, and appendices).
When will data be available (start and end dates)?
Beginning 12 months and ending 36 months following article publication.
Available to whom?
Investigators whose proposed use of the data has been approved by the University of Otago and Ministry of Primary Industries review committee.
Available for what types of analyses?
To achieve aims in the approved proposal.
How or where can data be obtained?
Proposals should be directed to sheila.skeaff@otago.ac.nz. To gain access, data requestors will need to sign a data access agreement.
What supporting documents are/will be available?
Study protocol
How or where can supporting documents be obtained?
Type [1] 8526 0
Study protocol
Citation [1] 8526 0
Link [1] 8526 0
Email [1] 8526 0
sheila.skeaff@otago.ac.nz
Other [1] 8526 0
Attachment [1] 8526 0
Summary results
No Results