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Trial registered on ANZCTR

Registration number

ACTRN12613000466741

Ethics application status

Approved

Date submitted

23/04/2013

Date registered

24/04/2013

Date last updated

26/09/2017

Type of registration

Prospectively registered

Titles & IDs

Public title

Identifying why some people consume excess fat. A twin study.

Scientific title

In healthy twin pairs, does a high fat diet over an eight week period, compared with a low fat diet, result in decreased sensitivity to the taste of fatty acids, lower satiety levels and increased preferences for high fat foods.

Secondary ID [1]

Nil

Universal Trial Number (UTN)

U1111-1142-2718

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Obesity

Condition category

Condition code

Diet and Nutrition

Obesity

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Eight week dietary intervention that is either high- or low-fat. These diets are equated for energy intake, with the high-fat diet consisting of 40% fat, 25% protein and 35% carbohydrate. The low-fat diet will consist of 20% fat, 25% protein and 55% carbohydrate. Diets will consist of different caloric intake for each individual participant based on their energy needs. Participants will have an initial consultation with a dietician (approx. 30 mins) prior to commencing the diet, and will be provided supplemental foods every two weeks throughout the intervention to assist with adherence to the diet. Further, participants will complete a one-day diet diary each week, and receive one short (5-10min) phone call each week to monitor compliance.

Intervention code [1]

Lifestyle

Intervention code [2]

Treatment: Other

Intervention code [3]

Prevention

Comparator / control treatment

The high-fat diet will be compared with a low-fat diet consumed for the same period of time.

Control group

Active

Outcomes

Primary outcome [1]

Taste sensitivity to fatty acids, as measured by determining the participant's threshold for detecting fatty acids in a milk solution. Participants will be given two control milk samples, with no fatty acid, and a third sample with increasing fatty acid concentration. Taste threshold will be determined when participants can correctly identify the milk with fatty acid identified three times in a row.

Timepoint [1]

Assessed at baseline, week four and week eight of the dietary intervention.

Primary outcome [2]

Preference for high fat foods. Participants will be given a series of high and low fat options (e.g. full fat compared with fat free chocolate mousse), without knowing which is which, and will have to choose which they prefer.

Timepoint [2]

Assessed at baseline, week four and week eight of the dietary intervention.

Primary outcome [3]

Fatty acid taste receptor expression. This will be determined by biopsy of fungiform papillae and subsequent RNA expression analysis.

Timepoint [3]

Assessed at baseline and week eight of the dietary intervention.

Secondary outcome [1]

PROP sensitivity. Participants will be given a sample of PROP, and will have to rate how it tastes on a general labelled magnitude scale.

Timepoint [1]

Baseline

Secondary outcome [2]

Papillae density. This is measured by staining the tongue with blue food dye in order to see the papillae more clearly. The tongue will be photographed, and the papillae within a certain area will be counted.

Timepoint [2]

Baseline

Secondary outcome [3]

Fat ranking ability. This will be tested by giving participants four custard samples with different fat concentrations, and asking them to rank them from highest to lowest fat.

Timepoint [3]

Baseline, week four and week eight of the dietary intervention.

Secondary outcome [4]

Lingual lipase, as determined by saliva samples.

Timepoint [4]

Baseline, week four and week eight of the dietary intervention.

Eligibility

Key inclusion criteria

Must be a twin (monozygotic or dizygotic). Must be able to speak English (as information and consent forms will not be translated).

Minimum age

18 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Individuals under 18. Individuals who do not speak English. Individuals who are not twins.

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)

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

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

30/06/2013

Actual

15/05/2014

Date of last participant enrolment

Anticipated

Actual

2/03/2016

Date of last data collection

Anticipated

Actual

4/07/2016

Sample size

Target

100

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

VIC

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

National Health and Medical Research Council

Address [1]

Level 1
16 Marcus Clarke Street
Canberra ACT 2601

Country [1]

Australia

Primary sponsor type

University

Name

Deakin University

Address

221 Burwood Hwy,
Burwood, 3125
Vic

Country

Australia

Secondary sponsor category [1]

Government body

Name [1]

CSIRO

Address [1]

CSIRO Enquiries
Locked Bag 10
Clayton South VIC 3169
Australia

Country [1]

Australia

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Deakin Human Research Ethics Committee

Ethics committee address [1]

221 Burwood Hwy, 
Burwood, 3125
Vic

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

24/04/2013

Approval date [1]

10/04/2014

Ethics approval number [1]

Summary

Brief summary

Obesity is a major health issue that is currently affecting millions of Australians, in addition to having a high economic cost both in this country and around the world. Some individuals are more susceptible to obesity than others; one factor may be variance in the taste system due to genetic and environmental factors such as diet. The present study aims to identify and investigate the mechanisms linking individual differences in taste with obesity. The mechanisms thought to be in play relate to our sense of taste, including taste receptors and their responsiveness to fatty acids, satiety levels resulting from consuming high fat foods, and food preferences. It is predicted that for susceptible individuals, consuming a high fat diet will negatively influence their responsiveness to fatty acids, increase their preference for high fat foods and decrease their hormonal and perceived satiety levels following food consumption. Each of these mechanisms has the potential to lead to an increase in dietary fat consumption, and BMI. Previous research has indicated that within pairs of BMI discordant monozygotic twins, the twin with the higher BMI has significantly lower taste responses to fatty acids, indicating that their diet may be related to their fatty acid taste sensitivity. 
This study aims to include 100 twin pairs (half monozygotic and half dizygotic) recruited from the Australian Twin Registry. These participants will be over 18 years of age. Twin pairs will be randomized into one of two weight maintenance diets (high- or low-fat). Participants will consume this allocated diet for eight weeks, with weekly diet diaries being assessed for compliance, in addition to weekly satiety questionnaires. Prior to baseline testing, participants will complete a four-day diet diary, the Cancer Council of Victoria food frequency questionnaire, the restrained eaters questionnaire, and a like-dislike questionnaire. Further testing will occur at baseline, week four and week eight. Each testing session will include a 24-hour dietary recall, taste function assessment, a fat-ranking task using custards, saliva samples, papillae density testing, preference testing for seven regular and low fat foods, anthropometry and a fungiform papillae biopsy. During baseline testing, participants will also be tested for PROP sensitivity, which is a heritable trait. Results will be compared at each time point to determine the effect of a high- or low-fat diet on fatty acid taste responses and satiety.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Prof Russell Keast

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Hwy,
Burwood, 3125
Vic

Country

Australia

Phone

+61 3 924 46944

Fax

russell.keast@deakin.edu.au

Contact person for public queries

Name

Russell Keast

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Hwy,
Burwood, 3125
Vic

Country

Australia

Phone

+61 3 924 46944

Fax

russell.keast@deakin.edu.au

Contact person for scientific queries

Name

Russell Keast

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Hwy,
Burwood, 3125
Vic

Country

Australia

Phone

+61 3 924 46944

Fax

russell.keast@deakin.edu.au

No information has been provided regarding IPD availability

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

Source	Title	Year of Publication	DOI
Embase	Effect of dietary fat intake and genetics on fat taste sensitivity: A co-Twin randomized controlled trial.	2018	https://dx.doi.org/10.1093/ajcn/nqy022
Embase	A low-fat diet up-regulates expression of fatty acid taste receptor gene FFAR4 in fungiform papillae in humans: a co-twin randomised controlled trial.	2019	https://dx.doi.org/10.1017/S0007114519002368

N.B. These documents automatically identified may not have been verified by the study sponsor.

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