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Trial registered on ANZCTR


Registration number
ACTRN12621001509853
Ethics application status
Approved
Date submitted
9/06/2021
Date registered
4/11/2021
Date last updated
4/11/2021
Date data sharing statement initially provided
4/11/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
Why does diet effect mood? Investigating the possible roles of psychological beliefs and biological changes that influence mood when undertaking a healthful diet.
Scientific title
A randomised control trial investigating the role of psychological and biological factors that drive mood change via diet intervention in individuals with low mood and poor diet.
Secondary ID [1] 303869 0
Nil
Universal Trial Number (UTN)
Trial acronym
The Dietrial
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Depression 321647 0
Anxiety 321648 0
Self-efficacy (aspects of self) 321649 0
Poor diet 324202 0
Condition category
Condition code
Mental Health 319393 319393 0 0
Depression
Mental Health 319394 319394 0 0
Anxiety
Diet and Nutrition 319395 319395 0 0
Other diet and nutrition disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Participants will be randomly allocated to one of four conditions: 1) fresh food condition, 2) canned and frozen food condition, 3) cooking condition, and 4) waitlist condition (see comparator/control treatment field below for more details).

Those in the fresh food condition will be instructed to increase intake of fish, fruits, vegetables, nuts, seeds, natural diary and wholegrain cereals, and decrease refined carbohydrate, sugar, fatty or processed meats and soft-drinks. Recommendations are based on the Australian Guide to Healthy Eating, as well as Mediterranean diet principles known to be associated with improved mood, incorporate BeyondBlue behavioural tips for eating well,
designed by a registered dietician and administered via video (approximately 10 - 20mins in length). The video provides information on the 5 major food groups in the Australian Guide to Healthy Eating (wholegrains, protein, dairy, fruit, vegetables), as well as recommendations to additionally consume specific foods known for their health benefits (olive oil, avocados, nuts and seeds, and spices). Participants will be provided a sample meal plan, shopping list and recipes, based on the Australian Guide to Healthy Eating. Participants will be provided online access to the diet intervention video and FAQs plus a questions facility on an online learning platform, monitored by the research team (incl. a registered psychologist). All diets will be ad libitum with no adherence to calorie restriction using the ingredients and reception provided.

Participants allocated to the canned and frozen food condition will be instructed to follow the same dietary changes as described in the fresh food condition above, however, they will be encouraged to consume a Mediterranean diet mainly via canned and frozen equivalents. They will be provided with the same sample meal plan and recipes as the fresh food condition, however adjusted to include canned and frozen ingredients alternatives. Participants will be provided online access to the diet intervention video and FAQs plus a questions facility on an online learning platform, monitored by the research team (incl. a registered psychologist), again with content adjusted to include canned and frozen ingredients. Participants will be asked to complete a diet diary once a week during the study to check for diet compliance.

In lieu of encouraging a Mediterranean based diet change, those in the cooking condition will be encouraged to continue consuming the same food they already typically eat, while being required to prepare and cook it for themselves, as opposed to purchasing takeout or pre-made packet items. For example, participants will be encouraged to shop for ingredients, prepare and cook their main meals such as pizza, toasties, burgers, chicken wings, and macaroni and cheese; as well as desserts including cookies, brownies, pastries and cakes, and snacks including milk shakes, scrolls, salted popcorn. They will be instructed to do this via the same resources (sample meal plans, recipes and online access to a learning platform) with the content adjusted accordingly. The cooking condition will also be required to complete a diet diary once a week. On day 21 the cooking group will be offered the resources used by the fresh food group.

All participants in the active conditions will be provided online access to the diet intervention video and answers to frequently asked questions. The intervention will last 3-weeks, and they will receive a telephone call mid intervention (approximately 5 minutes in length to answer any questions regarding the diet and check for diet adherence), as well as weekly text messages with a brief survey about their diet intake for the preceding day. To monitor diet adherence, all participants will be asked to submit grocery receipts (upon which they will receive a $60.00 grocery voucher to reimburse the cost of foods), complete a weekly diet diary, and have their skin carotenoid levels tested (via a spectrophotometer) before and after the study (contact will be reduced depending on general health recommendations during the global pandemic).
Intervention code [1] 320338 0
Treatment: Other
Intervention code [2] 320339 0
Lifestyle
Intervention code [3] 320340 0
Behaviour
Comparator / control treatment
Those in the wait list condition will be instructed to continue their diet as usual (meaning they continue consuming their typical diet with no changes). On day 21 the wait list group will be offered the resources used by the fresh food group.

Control group
Active

Outcomes
Primary outcome [1] 327254 0
Centre for Epidemiological Studies Depression Scale - Revised
Timepoint [1] 327254 0
Day 21 (last day of 3 week intervention).
Primary outcome [2] 327267 0
New General Self-Efficacy Scale
Timepoint [2] 327267 0
Day 21 (last day of 3 week intervention).
Primary outcome [3] 327268 0
Expectancy Bias:
The expectancy bias survey originally designed to measure expectancy bias in exercise interventions (Prodaniuk et al., 2004). A reliable and well established scale has been adjusted for diet for the purpose of this study. This adjusted for diet scale has been utilised in a recently published study (Smith et al., 2021).

References:
Smith, E., Stevenson, R., Dudley, L. and Francis, H. (2021), "The relationship of health-related expectancies, fruit and vegetable intake, and positive mood: expectancies are important, but not in the way you expect", British Food Journal, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/BFJ-03-2021-0289
Prodaniuk, T.R., Plotnikoff, R.C., Spence, J.C. et al. (2004). The influence of self-efficacy and outcome expectations on the relationship between perceived environment and physical activity in the workplace. Int J Behav Nutr Phys Act 1, 7 https://doi.org/10.1186/1479-5868-1-7
Timepoint [3] 327268 0
Day 21 (last day of 3 week intervention).
Secondary outcome [1] 394398 0
Body Mass Index - measure using height (measured via measuring tape), and weight (measured using electronic standing scales).
Timepoint [1] 394398 0
Day 21 (last day of 3 week intervention).

Eligibility
Key inclusion criteria
Elevated (>7) scores on the Depression, Anxiety and Stress Scale-21 Depression subscale (DASS-21-D); Score > 57 on the Dietary Fat and Sugar Screener (DFS); and score amongst the lowest quartile range for the Positive and Negative Affect Scale (PANAS - GEN).
Minimum age
17 Years
Maximum age
35 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Not pregnant, dieting, no history of eating disorders or metabolic disease(s), no history of psychological illness other than depression or anxiety, not experienced two or more failed trials of antidepressant, not reported medical condition that could be adversely affected by diet change, no known or suspected clinically unstable systemic medical disorder or gut based medical disorders i.,e Crohn's disease, no poor proficiency in English, no recent self-reported illicit drug or alcohol use, no sickness in the past week, and no food allergies. If a participant is receiving antidepressant medication or therapy, they need to be on the same treatment for at least 2 weeks before participation.

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 is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?


The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Sample size:
Using a Cohen’s power analysis, with on an estimated large effect size of d = .80, alpha level = .01 (one-tailed as direction is hypothesised), power = .80, we estimated that we would require a total of at least = 33 participants per group and therefore aim to recruit 40 per group (N = 160) based on a 10 - 15% dropout rate.

Data analysis:
ANCOVA: diet conditions (fresh food vs. canned and comfort food diet; between subject factors) with primary outcomes of mental health
Regression analysis: across conditions for primary outcomes of self-efficacy, aspects of self, expectancy bias, and bio-marker changes (within and between subject changes) against mental health outcomes
Paired t-tests: within subject pre- and post-intervention mental health outcomes
Chi-squared analysis: between group analysis
Intent-to-treat analysis: for missing data due to attrition

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
6/12/2021
Actual
Date of last participant enrolment
Anticipated
3/12/2022
Actual
Date of last data collection
Anticipated
30/12/2022
Actual
Sample size
Target
160
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 308264 0
University
Name [1] 308264 0
Macquarie University
Country [1] 308264 0
Australia
Primary sponsor type
University
Name
Macquarie University
Address
Macquarie University - Balaclava Rd,
Macquarie Park,
NSW 2109
Australia
Country
Australia
Secondary sponsor category [1] 309056 0
None
Name [1] 309056 0
Address [1] 309056 0
Country [1] 309056 0
Other collaborator category [1] 281773 0
Individual
Name [1] 281773 0
Jaime Rose Chambers
Address [1] 281773 0
Cooper Street Clinic
1 Cooper Street,
Double Bay NSW 2028.
Country [1] 281773 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 308242 0
Macquarie University Human Ethics Committee
Ethics committee address [1] 308242 0
Macquarie University, Balaclava Rd,
Macquarie Park,
NSW 2109,
Australia
Ethics committee country [1] 308242 0
Australia
Date submitted for ethics approval [1] 308242 0
19/01/2021
Approval date [1] 308242 0
23/04/2021
Ethics approval number [1] 308242 0
52021933327731

Summary
Brief summary
Several studies have now reported that modest improvements in diet (eating more fruit and vegetables) can lead to improvements in mood (Firth et al., 2019; Jacka et al., 2017; Parletta et al., 2019). In our recent study, Francis et al., (2019) demonstrated that a 3-week diet intervention for participants who reported low mood experienced significant improvement after the intervention, compared to controls. The usual explanation for these effects of diet is ‘physiological’. However, an alternative explanation is that positive expectations about a treatment (i.e., a placebo effect) and ‘taking control’ of events in your life (called self-efficacy) can both make you feel better. It is very likely that people believe that fresh food is good for you. It is also very likely that taking charge of ones’ diet is likely to increase feelings of self-efficacy. Together, these psychological effects could improve a person’s mood.

Therefore, the aim of our study is to investigate if the beneficial effects of a healthy diet on mood are in part from positive expectations and improved self-efficacy.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 110042 0
Prof Richard Stevenson
Address 110042 0
Psychology Department,
Macquarie University, Balaclava Rd,
Macquarie Park,
2109 NSW
Australia
Country 110042 0
Australia
Phone 110042 0
+610298508098
Fax 110042 0
Email 110042 0
[email protected]
Contact person for public queries
Name 110043 0
Leah Dudley
Address 110043 0
Psychology Department,
Macquarie University, Balaclava Rd,
Macquarie Park,
2109 NSW
Australia
Country 110043 0
Australia
Phone 110043 0
+61 040428593
Fax 110043 0
Email 110043 0
[email protected]
Contact person for scientific queries
Name 110044 0
Leah Dudley
Address 110044 0
Psychology Department,
Macquarie University, Balaclava Rd,
Macquarie Park,
2109 NSW
Australia
Country 110044 0
Australia
Phone 110044 0
+610400428593
Fax 110044 0
Email 110044 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
This was not requested as part of the ethics application.


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.