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Trial registered on ANZCTR


Registration number
ACTRN12615000922572
Ethics application status
Approved
Date submitted
18/08/2015
Date registered
3/09/2015
Date last updated
30/08/2016
Type of registration
Prospectively registered

Titles & IDs
Public title
Influence of habitual dietary fibre intake on the responsiveness of the gut microbiota to a prebiotic
Scientific title
Randomised double-blind, placebo-controlled, cross-over trial to determine the responsiveness of the gut microbiota to a prebiotic supplement in healthy individuals with differing habitual dietary fibre intakes
Secondary ID [1] 287135 0
Nil
Universal Trial Number (UTN)
U1111-1173-3522
Trial acronym
ADAPT study- hAbitual Diet And PrebioTic
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Prevention of suboptimal diet related health conditions, i.e. obesity

295682 0
Prevention of suboptimal diet related health conditions, i.e. diabetes 295986 0
Prevention of suboptimal diet related health conditions, i.e. cancer 295987 0
Prevention of suboptimal diet related health conditions, i.e. heart disease 295988 0
Condition category
Condition code
Diet and Nutrition 295958 295958 0 0
Obesity
Metabolic and Endocrine 295959 295959 0 0
Diabetes
Cardiovascular 296270 296270 0 0
Other cardiovascular diseases

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The intervention is an inulin/fructo-oligosaccharide prebiotic. Participants will take 16g per day (2x8g sachets taken with breakfast and dinner) of the prebiotic powder mixed into food and hot beverages for a duration of 3 weeks. After a 3 week washout period participants will also take 16g per day (2x8g sachets taken with breakfast and dinner) of placebo powder mixed into food and hot beverages for a duration of 3 weeks The study is 10 weeks in duration as there is also a 1 week run-in period at the beginning of the study.
Adherence to the intervention will be monitored using a daily diary and by asking the participants to return unused sachets.
Intervention code [1] 292394 0
Lifestyle
Intervention code [2] 292667 0
Prevention
Comparator / control treatment
The control treatment is a placebo which is a digestible maltodextrin. Participants will take 16g per day (2x8g sachets taken with breakfast and dinner) of the placebo powder mixed into food and hot beverages for a duration of 3 weeks.
Control group
Placebo

Outcomes
Primary outcome [1] 295705 0
To determine whether an individual’s habitual dietary fibre intake (high versus low, assessed using a validated food frequency questionnaire- Monash University Comprehensive Nutrition Assessment Questionnaire) influences the way in which the gut microbiota respond to a prebiotic as measured by bacterial relative abundance and bacterial diversity (alpha and beta diversity) assessed using next-generation sequencing analysis of faecal samples.
Timepoint [1] 295705 0
Bacterial relative abundance and bacterial diversity will be assessed before and after the 3 week long prebiotic and placebo interventions. Habitual dietary fibre intake will be assessed at baseline.
Primary outcome [2] 295706 0
To determine whether an individual's habitual dietary fibre intake (high vs. low, assessed using a validated food frequency questionnaire- Monash University Comprehensive Nutrition Assessment Questionnaire) influences the way in which the gut microbiota respond to a prebiotic as measured by bacterial short chain fatty acid (SCFA) production assessed using gas chromatography-mass spectrometer analysis of faecal samples.
Timepoint [2] 295706 0
SCFA production will be assessed before and after the 3 week long prebiotic and placebo interventions. Habitual dietary fibre intake will be assessed at baseline.
Secondary outcome [1] 316275 0
To determine whether baseline gut microbiota diversity (alpha and beta diversity), assessed by next-generation sequencing analysis of faecal samples, differ between individuals with high versus low habitual dietary fibre intakes.
Timepoint [1] 316275 0
This will be assessed at baseline.
Secondary outcome [2] 316276 0
To determine whether differing habitual dietary fibre intakes (high versus low) alters the efficacy of a prebiotic to influence appetite using a 100-mm anchored visual analogue scale appetite questionnaire.
Timepoint [2] 316276 0
Appetite will be assessed before and after the 3 week long prebiotic and placebo interventions.
Secondary outcome [3] 316277 0
To determine whether baseline SCFA levels differ between individuals with high versus low habitual dietary fibre intakes assessed using gas chromatography-mass spectrometer analysis of faecal samples.
Timepoint [3] 316277 0
This will be assessed at baseline.
Secondary outcome [4] 316278 0
To determine whether the utilisation of fructans, as assessed by enzymatic assay analysis of faecal samples, differs post prebiotic supplementation in individuals with differing habitual dietary fibre intakes (high versus low) assessed using a Fructan HK enzymatic assay kit.
Timepoint [4] 316278 0
Fructan utilisation will be assessed before and after the 3 week long prebiotic intervention.
Secondary outcome [5] 316279 0
To investigate any associations between body composition, as assessed by BodPod, and gut microbiota composition and function assessed using next-generation sequencing analysis of faecal samples. This is a composite.
Timepoint [5] 316279 0
This will be assessed at baseline.
Secondary outcome [6] 317100 0
To determine whether baseline gut microbiota relative abundance, assessed by next-generation sequencing analysis of faecal samples, differ between individuals with high versus low habitual dietary fibre intakes.
Timepoint [6] 317100 0
This will be assessed at baseline

Eligibility
Key inclusion criteria
The target population for recruitment are healthy male and female individuals between the age of 19 and 65 years with a BMI of between 18.5 and 30kg/m2. Individuals will need to have either a particularly low or high habitual dietary fibre intake to be considered eligible to participate in the study.
Minimum age
19 Years
Maximum age
65 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
* Aged <19 or >65 years
* Taken antibiotics within the last 6 months
* Taken laxatives, gastric motility medications, prebiotic or probiotic containing foods or supplements within the last month
* Of poor health- cancer, gastrointestinal disorders (irritable bowel syndrome, inflammatory bowel disease, coeliac disease, constipation, diarrhoea, excessive bloating), autoimmune disorders, diabetes, heart disease, renal failure
* BMI <18.5 or >30kg/m2
* Significant weight loss or weight gain (>5%) within the past year
* Significant dietary change within the past year
* Pregnant, breastfeeding or planning a pregnancy
* Food intolerance which causes gastrointestinal symptoms (i.e. lactose intolerance, gluten sensitivity)
* Smokers
* High alcohol consumers

If a potential participant is only ineligible to participate in the study because they are taking prebiotic or probiotic containing foods or supplements they can become eligible for inclusion in the study if they are willing to discontinue these foods or supplements for a month prior to starting the study and during the study.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
As this is a cross-over study all participants will receive the prebiotic and placebo treatments however the order in which they receive the treatments will be concealed from the participant and lead researcher. The research unit laboratory manager will be responsible for allocating the treatment order for each participant.
The treatments will be sealed in opaque bags and will only be labelled as treatment A or B therefore the participant and lead researcher (who is administering the treatments, assessing outcomes and analysing data) will not know the order of treatment allocation.
The appearance and taste of the treatments are similar and both treatments will be packed into sachets which will help to conceal which treatment the participants are taking. The treatments will be packed into sachets off site.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be randomised using a computer based pre-generated treatment order as participants will be recruited one at a time over a number of months.
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
NA
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
The power calculations have been conducted to detect a significant increase in Bifidobacteria species as this is the main outcome measure in the prebiotic studies reviewed. As improved appetite is a key secondary outcome power calculations have also been conducted to ensure significant differences in appetite can be detected.
Based on the studies reviewed (split plot design crossover) in order to detect a significant difference in abundance of Bifidobacteria species between the placebo and treatment groups, with a power of 80% and significance of 5%, an average of 24 participants need to be recruited. To allow for drop outs (approximately 10%) and the more subtle differences which are likely to be seen when determining the response of Bifidobacteria species to a prebiotic when comparing low and high habitual dietary fibre consumers rather than the treatment to placebo group, a total of 40 participants will need to be recruited.
Based on the studies reviewed (split plot design crossover) in order to detect a significant difference in appetite between the control and treatment groups, with a power of 80% and significance of 5%, 3 participants need to be recruited. The recruitment of 40 participants will therefore be enough to determine whether there are any differences in appetite after prebiotic consumption between individuals with high and low habitual dietary fibre intakes.

Phyla and genus taxonomy abundance data will be analysed using non-parametric Mann-Whitney test. Alpha diversity will be analysed using non-parametric two sample t-tests.

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 outside Australia
Country [1] 7061 0
New Zealand
State/province [1] 7061 0
Manawatu

Funding & Sponsors
Funding source category [1] 291748 0
Government body
Name [1] 291748 0
The New Zealand Institute of Plant and Food Research Limited
Address [1] 291748 0
Batchelar Road
Fitzherbert
Palmerston North
4474
Country [1] 291748 0
New Zealand
Primary sponsor type
Individual
Name
Genelle Healey
Address
Plant and Food Research Limited
Batchelar Road
Fitzherbert
Palmerston North 4474
Country
New Zealand
Secondary sponsor category [1] 290418 0
Individual
Name [1] 290418 0
Dr Chrissie Butts
Address [1] 290418 0
Plant and Food Research Limited
Batchelar Road
Fitzherbert
Palmerston North 4474
Country [1] 290418 0
New Zealand
Secondary sponsor category [2] 290569 0
Individual
Name [2] 290569 0
A/Prof Jane Coad
Address [2] 290569 0
School of Food and Nutrition
Massey University
Tennent Drive
Palmerston North 4474
Country [2] 290569 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 293267 0
Massey University Human Ethics Committee
Ethics committee address [1] 293267 0
Massey University
Tennent Drive
Palmerston North 4474
Ethics committee country [1] 293267 0
New Zealand
Date submitted for ethics approval [1] 293267 0
26/05/2015
Approval date [1] 293267 0
08/07/2015
Ethics approval number [1] 293267 0
15/34

Summary
Brief summary
Research has shown that the type of food consumed can influence the bacteria in the gastrointestinal tract (gut). It has also been shown that the bacteria in the gut can have an influence on human health. The presence of “unfavourable” bacteria within the gut has been linked to obesity, diabetes and some gastrointestinal disorders such as inflammatory bowel disease and irritable bowel syndrome. Researchers are therefore trying to determine what can be done to ensure the bacteria living in our gut are “favourable” to help optimise human health. A number of fibre supplements, known as prebiotics, have been shown to improve human health through their actions on “favourable” gut bacteria. Prebiotics are not digested by humans and therefore reach the large bowel where they are used by the gut bacteria as a source of energy.
The amount of dietary fibre consumed between individuals varies considerably. We hypotheses that if someone is already consuming foods high in dietary fibre their gut bacteria will likely respond in a different way to a prebiotic supplement than the gut bacteria of an individual with a low intake of dietary fibre foods. The aim of the study is to determine what influence an individuals long term dietary fibre intake has on how their gut bacteria respond to a prebiotic supplement.
Trial website
www.massey.ac.nz/adaptstudy
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 58958 0
Mrs Genelle Healey
Address 58958 0
Plant and Food Research
Batchelar Road
Fitzherbert
Palmerston North 4474
Country 58958 0
New Zealand
Phone 58958 0
+64 6 355 6108
Fax 58958 0
Email 58958 0
genelle.healey@plantandfood.co.nz
Contact person for public queries
Name 58959 0
Mrs Genelle Healey
Address 58959 0
Plant and Food Research
Batchelar Road
Fitzherbert
Palmerston North 4474
Country 58959 0
New Zealand
Phone 58959 0
+64 6 355 6108
Fax 58959 0
Email 58959 0
genelle.healey@plantandfood.co.nz
Contact person for scientific queries
Name 58960 0
A/Prof Jane Coad
Address 58960 0
School of Food and Nutrition
Massey University
Tennent Drive
Palmerston North 4474
Country 58960 0
New Zealand
Phone 58960 0
+64 6 951 6321
Fax 58960 0
Email 58960 0
j.coad@massey.ac.nz

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary