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Trial registered on ANZCTR


Registration number
ACTRN12619000178145p
Ethics application status
Submitted, not yet approved
Date submitted
29/01/2019
Date registered
7/02/2019
Date last updated
7/02/2019
Date data sharing statement initially provided
7/02/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
The influence of gene variants on physiological responses to a Mediterranean diet - a nutritional genomics focus,
Scientific title
The influence of gene variants on gut bacteria diversity and composition, and levels of blood metabolites involved in glucose, fat and protein metabolism in healthy adults on a Mediterranean diet - a nutritional genomics focus.
Secondary ID [1] 297234 0
None
Universal Trial Number (UTN)
Not applicable
Trial acronym
MEDGEN
Linked study record
This study is not linked to another study.

Health condition
Health condition(s) or problem(s) studied:
Cardiovascular Disease 311297 0
Type 2 Diabetes 311384 0
Condition category
Condition code
Diet and Nutrition 309923 309923 0 0
Other diet and nutrition disorders
Metabolic and Endocrine 310020 310020 0 0
Diabetes
Cardiovascular 310049 310049 0 0
Coronary heart disease
Cardiovascular 310050 310050 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Clinical Sessions (approximately 3 hours each):

Eligible participants will be asked to attend the Clinical Trial Suites at RMIT University Bundoora (Building 203) and asked to bring the signed consent form. Participants will be asked to complete a personal information and medical questionnaire.
During the initial (baseline) clinical session participants will perform a standard buccal swab (this will not be repeated in subsequent clinical sessions). Each buccal swab will be used for genetic profiling using Single Nucleotide Polymorphism arrays.

During the clinical session participants will be weighed, measured for height and have their hip to weight ratio recorded. Blood pressure will be measured using a sphygmomanometer. Participants will have their body composition measured using Dual-Energy X-ray Absorptiometry (DEXA).

Participants will then be asked to wear a respiratory mouth piece and nose clip (for approximately 10 mins) to have their respiratory gases measured every 30 seconds via an open-circuit sampling system. Respiratory data will be used to determine resting metabolic rate and each participant’s daily energy requirements.

Following this, participants will perform a standard oral glucose tolerance test (OGTT) to determine glucose handling. Blood samples will be taken prior to, at 30-mins, 60-mins and 120-mins following glucose ingestion for subsequent measure.

Habitual dietary intake will be measured using a 3-day food record (2 weekdays and 1 weekend day). Participants will be asked to complete a food frequency questionnaire. Dietary quality will be assessed using the Healthy Eating Index (Basiotis et al. 2002). Mood State will be analysed using the Profile of Mood State questionnaire and the Hospital Anxiety and Depression Scale questionnaire. These questionnaires will be administered whilst the participants are undertaking the OGTT. Stool samples will be collected by participants using a stool collection kit.

During the 1st and 2nd clinical session, the participant will also consult with the Accredited Practising Dietitian for approximately 45min-1hour to explain the dietary intervention phase and to collect food diaries. In the final clinical session the Accredited Practising Dietitian will also meet with the participant to collect final food diaries and food frequency questionnaires.

Following the initial (baseline) clinical session participants will be eligible to commence the dietary intervention and will be randomly assigned to either the 8-week Mediterranean dietary intervention or the 8-week General Healthy Eating intervention (Control). This dietary intervention timeframe has demonstrated physiological changes on a molecular and metabolic level (Bondia-Pons et al. 2015; Marques-Rocha 2016).

A post intervention clinical session (as described above) will be repeated at the end point of the first 8-week dietary intervention period. The participant will then cross-over to the 8-week dietary intervention they have not yet completed. There will be no washout period. Total duration of the combined dietary intervention period will be 16 weeks. A final (third) clinical session will be repeated at week 16.

Dietary Intervention Mediterranean (8-weeks):
Each participant will receive a detailed sample Mediterranean meal plan, recipes, and education material to assist with adherence to a Mediterranean diet for the 8-week period. This will be explained by an Accredited Practising Dietitian during the clinical session. This task will be facilitated by providing a calibrated scale, a menu plan to each participant, along with a food hamper with food items that will be used as part of a Mediterranean diet.
Each Mediterranean meal plan will adhere to the Mediterranean diet developed in the Mediterranean Diet Model in Australia: Strategies for Translating the Traditional Mediterranean Diet into a Multicultural Setting study (George et al. 2018) and the validated protocols used in the PREDIMED trials (Martinez-Gonzalez et al. 2012). This includes using extra virgin olive oil (minimum 3-4 tablespoons per day), eating vegetables with every meal (100g leafy greens, 100g other vegetables, 100g tomatoes per day), at least two serves of fruit per day, legumes at least twice per week, at least three serves of fish per week, red meat less often, one serve of nuts daily, two serves of dairy daily (milk and yoghurt preferable), cheese in moderation (three days per week preferably feta, 1 serve equalling 30 grams), choice of wholegrain breads and cereals, consuming 3 eggs per week, sweets to be consumed in moderation (preferably homemade), red wine is optional (0-2 standard glasses per day, with meals, instructions to not get intoxicated). Advice on alcohol will be provided to those who already consume alcohol in their habitual diet.

Dietary Intervention General Healthy Eating (8-weeks):
Each participant will be provided with general healthy eating advice in accordance to the Australian Guide to Healthy Eating (AGTHE). This task will be facilitated by providing the participant with relevant education material, a guide to food groups and portion/serve sizes, with a focus on high fibre, low fat eating and reduced intake of discretionary foods. This diet has been chosen as a control diet based on previous literature and to also reflect current dietetic advice provided in practice to the Australian population (Papamiltiadous et al. 2016; Itsiopoulos et al. 2018).

Dietary intake will be measured using a 3-day weighed food record during the intervention mid-point (week 4) and the week before the end of each dietary intervention (week 7/prior to the post intervention clinical session). Adherence to the Mediterranean diet will be assessed using the Mediterranean Diet Adherence Screener Score (MEDAs) tool.

An ad libitum approach for each diet will be advised, based on previous literature (Papamiltiadous et al. 2016; Jacka et al. 2017; Itsiopoulos et al. 2011; Itsiopoulos et al. 2018; Ryan et al. 2013).

The participant will consult with the Accredited Practising Dietitian during each clinical session for approximately 45-60 minutes (week 1, week 8 and week 16). The participant will also receive weekly telephone calls to support the participant throughout the dietary intervention.

Participants will be instructed to maintain their habitual physical activity patterns during the intervention, with physical activity patterns monitored and evaluated weekly by informal individual support-orientated phone calls throughout the 8-week intervention. Food recall strategies will be adopted by researchers throughout these phone calls to monitor and evaluate dietary compliance.
Intervention code [1] 313486 0
Lifestyle
Comparator / control treatment
Dietary Intervention General Healthy Eating (8-weeks):
Each participant will be provided with general healthy eating advice in accordance to the Australian Guide to Healthy Eating (AGTHE). This task will be facilitated by providing the participant with relevant education material, a guide to food groups and portion/serve sizes, with a focus on high fibre, low fat eating and reduced intake of discretionary foods. Adherence to the diet will monitored with a 3 day weighted food record. This diet has been chosen as a control diet based on previous literature and to also reflect current dietetic advice provided in practice to the Australian population (Papamiltiadous et al. 2016; Itsiopoulos et al. 2018).


Control group
Active

Outcomes
Primary outcome [1] 318853 0
Blood metabolites associated with glucose, fat and protein metabolism will be assessed using metabolic profiling techniques. Gas Chromatography-Mass Spectrophotometry (GC-MS). Plasma microRNA will be performed using microarray analysis and real-time-PCR. There are no specific metabolites chosen, This will be an exploratory outcome/untargeted approach.

Timepoint [1] 318853 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Primary outcome [2] 318888 0
Gene expression analysis. Microarray kits and real-time PCR will be used for analysis of the DNA (buccal swab). There are no specific genes, rather it will be an exploratory outcome.

Timepoint [2] 318888 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Primary outcome [3] 318889 0
Gut bacteria diversity and composition. This will be measured using faecal sample collection kits and 16S rRNA profiling.
Timepoint [3] 318889 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Secondary outcome [1] 366256 0
Circulating hormone insulin (primary outcome). Enzyme-linked immunoabsorbent assay (ELISA) kits will be used for analysis using the plasma samples.
Timepoint [1] 366256 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Secondary outcome [2] 366333 0
Body composition will be measured using a Dual-Energy X-ray Absorptiometry (DEXA) machine.
Timepoint [2] 366333 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Secondary outcome [3] 366334 0
Glucose tolerance will be measured via an Oral Glucose Tolerance Test. Blood samples will be measured with serum assays.
Timepoint [3] 366334 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).
Secondary outcome [4] 366335 0
Food frequency and nutrient intake will be measured with a 3 day weighted food diary. Validated food frequency questionnaires will be used to assess food intake (120 item Australian Healthy Eating survey by O'Brien et al. 2014). This is a composite outcome.
Timepoint [4] 366335 0
Food frequency and nutrient intake will be measured with a 3 day weighted food diary at baseline, mid-point (week 4) and at the end of each dietary intervention (week 8).
Validated food frequency questionnaires will be used to assess food intake at baseline to assess dietary habits for the previous 6 months, and then post each 8 week dietary intervention.
Secondary outcome [5] 366336 0
Mood state will be assessed with validated questionnaires. The Profile of Mood States (POMS) questionnaire and the Hospital Anxiety and Depression Scale (HADS) will be used.
Timepoint [5] 366336 0
At each clinical session (week 1, 8 and 16).
Secondary outcome [6] 366498 0
Circulating hormone ghrelin (primary outcome). Enzyme-linked immunoabsorbent assay (ELISA) kits will be used for analysis using the plasma samples.
Timepoint [6] 366498 0
A baseline measure (week 1) and week 8 of each dietary intervention (end of each diet phase).

Eligibility
Key inclusion criteria
Individuals with a body mass index greater than 18.5 kg/m2, males and females aged between 18 - 55 years who are deemed eligible to participate as indicated by not meeting one or more of the exclusion criterion.
Minimum age
18 Years
Maximum age
55 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Participants will be excluded from participating within the project for the following reasons: Individuals with presence of psychiatric disorders, pathologic eating disorders, chronic diseases related to the metabolism of energy and nutrients (i.e. hyperthyroidism), difficulty in changing food habits, participants with special dietary needs (e.g. exclusion of whole food groups), and/or unable or unwilling to give informed consent. These exclusion criterion are set as they may influence an individual’s ability to comply with the recommendations of the nutritional intervention.
Additional exclusion criterion includes: weight instable in the previous 3 months (evident by a loss or gain of more than 10% of total body weight), pregnant or potentially pregnant, post-menopausal, taking contraindicated mediation (e.g. antibiotics, thyroid, hyperlipidemic, hypoglycemic, hypertensives, psychotropic drugs or appetite suppressants) or the use of any dietary supplement that might interfere with the results of the study. These additional exclusion criteria are set as the may exert an independent influence on microbiome and metabolic outcomes, anthropometric, biochemical, clinical, body composition (DEXA) analysis and/or dietary outcomes monitored throughout the intervention.

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 from a statistic book.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Statistical power for a sample size of at least 120 participants to detect a medium effect size with 80% power was calculated upon previously published data on cross-over (Itsiopoulous et al. 2011 (n=27); Ryan et al. 2013 (n=12)) and single arm studies (Di Renzo et al. 2018 (n=188, split on FTO genotype); Jacka et al. 2017 (n=67); Papamiltiadous et al. 2016 (n=94); Parletta et al. 2007 (n=152)). In these studies, a 6 week to 3-month Mediterranean diet - control intervention was able to have a significant influence on a variety of physiological and psychological outcomes. Based on allowances for attrition, including predicted dropout rates, sample size was inflated by 20% for the current project (to n=120 overall), which takes a randomised cross over approach and accounts for genotypic influences on data outcomes.

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)
VIC

Funding & Sponsors
Funding source category [1] 301789 0
Charities/Societies/Foundations
Name [1] 301789 0
Allen Foundation Inc
Address [1] 301789 0
P.O. Box 1606
Midland, Michigan 48641-1606
U.S.A
Country [1] 301789 0
United States of America
Primary sponsor type
Individual
Name
Dr. Jessica Danaher
Address
RMIT University Bundoora West Campus
Plenty Road
Bundoora, VIC 3083
Country
Australia
Secondary sponsor category [1] 301531 0
None
Name [1] 301531 0
Address [1] 301531 0
Country [1] 301531 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 302501 0
Royal Melbourne Institute of Technology Human Research Committee
Ethics committee address [1] 302501 0
RMIT University
GPO Box 2476
Melbourne 3001
Victoria
Ethics committee country [1] 302501 0
Australia
Date submitted for ethics approval [1] 302501 0
29/01/2019
Approval date [1] 302501 0
Ethics approval number [1] 302501 0

Summary
Brief summary
This project is designed to determine if specific genetic sub-groups associated with metabolic disease risk benefit from a Mediterranean diet. This research may lead to personalised nutrition recommendations using genomic information to promote health.

The aims of the proposed project are to:

(i) Determine the influence of an 8-week Mediterranean dietary intervention on gut bacteria, levels of metabolites (involved in glucose, fat and protein metabolism) present in blood, and gene modifiers (whether genes are turned on or off) in blood. This will be compared to a person’s habitual diet (baseline results) and a general healthy eating diet following The Australian Guide to Healthy Eating (control diet).

(ii) Determine the potential of key genetic variants related to metabolic disease (including the Fat Mass and Obesity-Associated (FTO) gene, Transcription Factor 7-Like 2 (TCF7L2) gene, and Apolipoprotein E (APOE) gene) to influence gut bacteria, blood metabolite and gene modifying outcomes in response to the dietary interventions.

(iii) Determine whether differences between genetic variants exist for body composition, key hormones (ghrelin and insulin), glucose tolerance, and dietary intake (food frequency and nutrient composition) in response to the dietary interventions.

It is hypothesized that variations in key genes associated with metabolic disease impacts on gut bacteria, blood metabolites and gene modifiers following an 8-week Mediterranean dietary intervention.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 90430 0
Dr Jessica Danaher
Address 90430 0
RMIT University
GPO Box 2476
Melbourne 3001
Victoria

Country 90430 0
Australia
Phone 90430 0
+61 3 9925 6117
Fax 90430 0
+61 3 9925 6575
Email 90430 0
jessica.danaher@rmit.edu.au
Contact person for public queries
Name 90431 0
Dr Jessica Danaher
Address 90431 0
RMIT University
GPO Box 2476
Melbourne 3001
Victoria

Country 90431 0
Australia
Phone 90431 0
+61 3 9925 6117
Fax 90431 0
+61 3 9925 6575
Email 90431 0
jessica.danaher@rmit.edu.au
Contact person for scientific queries
Name 90432 0
Dr Jessica Danaher
Address 90432 0
RMIT University
GPO Box 2476
Melbourne 3001
Victoria

Country 90432 0
Australia
Phone 90432 0
+61 3 9925 6117
Fax 90432 0
+61 3 9925 6575
Email 90432 0
jessica.danaher@rmit.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
The participant's personal data will not be identifiable/published in isolation. The data will be published as a mean +/- standard error of the mean (SEM) of the combined group.
What supporting documents are/will be available?
Study protocol
How or where can supporting documents be obtained?
Type [1] 1202 0
Study protocol
Citation [1] 1202 0
Link [1] 1202 0
Email [1] 1202 0
Other [1] 1202 0
Summary results
No Results