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Trial registered on ANZCTR


Registration number
ACTRN12620001250921
Ethics application status
Approved
Date submitted
23/09/2020
Date registered
20/11/2020
Date last updated
1/12/2020
Date data sharing statement initially provided
20/11/2020
Date results information initially provided
20/11/2020
Type of registration
Retrospectively registered

Titles & IDs
Public title
Role of naturally occurring dietary salicylates in Irritable Bowel Syndrome
Scientific title
Role of naturally occurring dietary salicylates in Irritable Bowel Syndrome: Investigating impact on gastrointestinal symptoms
Secondary ID [1] 302319 0
None
Universal Trial Number (UTN)
U1111-1258-3073
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Irritable bowel syndrome 319082 0
Condition category
Condition code
Oral and Gastrointestinal 317030 317030 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Brief name: Low salicylate diet
Comparator diet: High salicylate diet (see below)

Overall design: This was a pilot, double-blind, randomised, cross-over trial of low versus high-salicylate diets in IBS patients who had no previous exposure to a low chemical diet.

Materials: Participants were randomized by a computer-generated order to receive a diet either low or high in salicylate content for 14-days (6.6 and 27.9 g/day salicylate respectively). All food was provided. Participants and investigators were blinded to the diet. After the initial 14-days, the participants undertook a washout period of 7 days, where they resumed their habitual diet. No food was provided during this phase. During the washout phase, they completed a diary recording their symptoms and the amount and type of food they ate. This was followed by a cross-over to the alternate diet for further 14 days.

During the interventional dietary phases, all participants were provided with food and they completed information on the quantity of the provided foods consumed.

Interventional diets:
All foods including three main meals, morning and afternoon snacks, and drinks were provided. Detailed meal plans for high- and low-salicylate diets were provided to the participants. For some meals that included fresh salads, detailed recipes were provided for participants to prepare before consumption. They were strictly instructed to avoid eating out during the course of the study. If participants wanted to eat foods that were not specified on the supplied list, they contacted the study investigator for guidance on food choices.

Who provided intervention delivery & mode of delivery: The study investigator and two professional chefs prepared all foods in the commercial kitchen of Department of Dietetics, Monash University. Frozen complete meals were provided to the participants with instructions to thaw and heat before consumption. The foods were delivered bi-weekly free of charge to the participant homes.

The diets were designed based upon the salicylate content of foods. Both diets were free of gluten, preservatives, additives and lactose, were consistent in their levels of minimal FODMAPs (fermentable oligo- di- mono-saccharides and polyols), and contained moderate levels of amines and glutamates as per published food content to avoid any confounding factors that might affect the symptoms.

The average daily intake of salicylates in the low-salicylate diet was approximately 6 mg. The meal plans had an average energy value of 8 MJ daily and met the recommended serves of all food groups according to the Australian dietary guidelines.

Location: The intervention occurred within the participants home.
Personalisation: The intervention was not personalised to each patient.
Adherence: Compliance was monitored via the daily food diaries.
Intervention code [1] 318640 0
Treatment: Other
Comparator / control treatment
Comparator diet: High salicylate diet

The average daily intake of salicylates in the high-salicylate diet was 28 mg. The meal plans had an average energy value of 8 MJ daily and met the recommended serves of all food groups according to the Australian dietary guidelines.
Control group
Active

Outcomes
Primary outcome [1] 325176 0
The primary endpoint was the difference in overall gastrointestinal symptoms measured by the 100-mm Visual Analogue Scale on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [1] 325176 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [1] 387088 0
Secondary endpoint included differences between the diets in abdominal pain measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [1] 387088 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [2] 387089 0
Secondary endpoint included differences between the diets in headache/migraine measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [2] 387089 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [3] 387090 0
Secondary endpoint included differences in symptoms (i.e. both gastrointestinal and extra-intestinal as per the other secondary outcomes) between interventional diets and their respective preceding control phases of baseline or washout measured by the 100-mm VAS.
Timepoint [3] 387090 0
Comparisons were made using average symptom scores of the last three days of the preceding control period compared to the last three days of each of the interventional dietary periods.
Secondary outcome [4] 388134 0
Secondary endpoint included differences between the diets in bloating measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [4] 388134 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [5] 388135 0
Secondary endpoints included differences between the diets in passage of wind measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [5] 388135 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [6] 388136 0
Secondary endpoint included differences between the diets in nausea measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [6] 388136 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [7] 388137 0
Secondary endpoint included differences between the diets in rhinitis (stuffy or runny nose, post-nasal drip) measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [7] 388137 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [8] 388138 0
Secondary endpoint included differences between the diets in asthma measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [8] 388138 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [9] 388139 0
Secondary endpoint included differences between the diets in eczema measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [9] 388139 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [10] 388140 0
Secondary endpoint included differences between the diets in urticaria measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [10] 388140 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.
Secondary outcome [11] 388141 0
Secondary endpoint included differences between the diets in tiredness measured by the 100-mm VAS on the low-salicylate diet compared to those on the high-salicylate diet.
Timepoint [11] 388141 0
All comparisons were made using average symptom scores of the last three days of the respective dietary periods.

Eligibility
Key inclusion criteria
Patients with irritable bowel syndrome based on Rome III criteria.
Minimum age
18 Years
Maximum age
75 Years
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
- coeliac disease
- pregnancy and breastfeeding,
- other significant co-morbid conditions such as diabetes and inflammatory bowel disease.
- previously received advice or information on a low chemical diet.
- taking pharmacological agents like laxatives to alter their symptoms.
- taking aspirin or any other drugs containing or delivering salicylates for at least two weeks prior to the commencement of the study.

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)
Central randomisation by computer.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
This was a pilot study and hence power calculations were not undertaken.

Paired t-test and non-parametric statistical analyses are used as appropriate. For non-parametric analyses, Friedman test and Wilcoxon signed rank tests were performed to compare the abdominal symptoms between high- and low-salicylate dietary interventions.

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 in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 17577 0
The Alfred - Melbourne
Recruitment postcode(s) [1] 31319 0
3004 - St Kilda Road Melbourne
Recruitment postcode(s) [2] 31320 0
3004 - Melbourne

Funding & Sponsors
Funding source category [1] 306745 0
University
Name [1] 306745 0
Monash University
Address [1] 306745 0
Department of Gastroenterology
Central Clinical School
The Alfred Centre
99 Commercial Road
Melbourne 3004
VIC
Country [1] 306745 0
Australia
Primary sponsor type
University
Name
Monash University
Address
Department of Gastroenterology
Central Clinical School
The Alfred Centre
99 Commercial Road
Melbourne 3004
VIC
Country
Australia
Secondary sponsor category [1] 307297 0
None
Name [1] 307297 0
N/A
Address [1] 307297 0
N/A
Country [1] 307297 0
Other collaborator category [1] 281560 0
University
Name [1] 281560 0
Dr Jane Muir
Address [1] 281560 0
Department of Gastroenterology
Central Clinical School
The Alfred Centre
99 Commercial Road
Melbourne 3004
VIC
Country [1] 281560 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 306917 0
Monash University Human Research Ethics Committee
Ethics committee address [1] 306917 0
Building 3E, Room 111,
Clayton Campus,
Monash University,
Wellington Road,
Clayton 3800
VICTORIA
Ethics committee country [1] 306917 0
Australia
Date submitted for ethics approval [1] 306917 0
Approval date [1] 306917 0
17/07/2014
Ethics approval number [1] 306917 0
CF14/1642 – 2014000780

Summary
Brief summary
An therapeutic diet targeting naturally-occurring bioactive chemicals has been suggested to relieve gastrointestinal symptoms. A major focus of this diet is salicylates. This study aimed to address a potential role of dietary salicylates in causing symptoms in patients with irritable bowel syndrome (IBS). A pilot, double-blind, randomised, cross-over trial of two-week low-versus high-salicylate diets was undertaken. All food was provided containing minimal quantities of other potential food triggers. Gastrointestinal and extra-intestinal symptoms were measured daily using a 100-mm visual-analogue-scale. We hypothesised that a low salicylate diet would improve symptoms compared to the high salicylate diet in the 10 patients with IBS who conducted the study.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 105438 0
Prof Peter Gibson
Address 105438 0
Department of Gastroenterology,
Alfred Hospital,
Level 6,
99 Commercial Rd,
Melbourne, VIC 3004,
Country 105438 0
Australia
Phone 105438 0
+613 9076 3325
Fax 105438 0
Email 105438 0
peter.gibson@monash.edu
Contact person for public queries
Name 105439 0
Dr Caroline Tuck
Address 105439 0
La Trobe University
Plenty Rd and Kingsbury Dr
Bundoora
VIC 3086
Country 105439 0
Australia
Phone 105439 0
+613 94792168
Fax 105439 0
Email 105439 0
c.tuck@latrobe.edu.au
Contact person for scientific queries
Name 105440 0
Dr Caroline Tuck
Address 105440 0
La Trobe University
Plenty Rd and Kingsbury Dr
Bundoora
VIC 3086
Country 105440 0
Australia
Phone 105440 0
+613 94792168
Fax 105440 0
Email 105440 0
c.tuck@latrobe.edu.au

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 underlying published results only
When will data be available (start and end dates)?
Beginning 3 months and ending 5 years following main results publication
Available to whom?
On request on a case-by-case basis at the discretion of Primary Sponsor
Available for what types of analyses?
For IPD meta-analyses
How or where can data be obtained?
Access subject to approvals by Principal Investigator (peter.gibson@monash.edu)
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
No
Other publications
Have study results been made publicly available in another format?
No
Results – plain English summary