The effect of odour exposure on appetite, appetite for smelled foods and salivation, investigated for different odours

ISRCTN	ISRCTN39512795
DOI	https://doi.org/10.1186/ISRCTN39512795
Secondary identifying numbers	NL35493.081.11

Submission date: 13/12/2012
Registration date: 31/01/2013
Last edited: 31/01/2013

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Nutritional, Metabolic, Endocrine

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
In view of the obesity epidemic, it is important to understand which factors determine the appetizing and/or satiating responses to food cues. It is well known that short exposure to food cues, e.g. the sight or odour of freshly baked bread or pizza, can enhance salivation and appetite feelings. On the other hand, people report to be less hungry after cooking a meal, which is exposure to sight and odour of food for a longer period of time. In this study, we want to investigate some aspects of this apparent paradox. The primary objective is to investigate the effect of exposure to several odours on appetite, appetite for the smelled food and salivation over time.

Who can participate?
Unrestrained healthy women, 18-45 yr old, BMI 18.5 25 kg / m2

What does the study involve?
Participants were expected in the lab for 6 times, around lunch time. During every visit, the response to two different test conditions was measured (two test sessions were conducted on one day), resulting in 12 sessions. The first session was a practice session to get the participants acquainted to the procedure. During the remaining 11 session, the participants were exposed to two control sessions with no odour and nine sessions with different odours. During each session, salivation, hunger, appetite, appetite for different kind of foods and food preference was measured. Each session started with baseline measurements in which participants answered the appetite questionnaire and salivation was measured, in a room with no odour present. Subsequently, each participant entered one of the test rooms that contained either one of the odours or no-odour. The participants were given instructions on a computer. The appetite questionnaire was filled out 1, 5 9, 13 and 18 minutes after entering the room and the saliva collected 0.5, 4, 8 and 17 minutes after entering the room. After 20 minutes, the participants entered another room with no odour to complete a food preference questionnaire. When finished, participants received a snack.

What are the possible benefits and risks of participating?
A fee of 90 euros was paid upon completion of the study. Compared to other studies the burden can be considered as low. No possible health benefits.
The risk associated with participation is negligible.

Where is the study run from?
Restaurant of the Future (Netherlands).

When is the study starting and how long is it expected to run for?
The start date was 2 May 2011. The duration of the trial was 8 weeks.

Who is funding the study?
Technology Foundation STW (Stichting Technische Wetenschappen) (Netherlands).

Who is the main contact?
Marielle Ramaekers
marielle.ramaekers@wur.nl

Contact information

Mrs Marielle Ramaekers
Scientific

Bomenweg 2
Wageningen
6703 HD
Netherlands

Phone	+31 (0)317 482520
Email	marielle.ramaekers@wur.nl

Study information

Study design	Cross-over study
Primary study design	Interventional
Secondary study design	Randomised controlled trial
Study setting(s)	Other
Study type	Screening
Participant information sheet	Not available in web format, please use the contact details below to request a patient information
Scientific title	Effect of orthonasal odour exposure time on appetite, appetite for smelled foods and salivation, investigated for different odours: a cross-over study
Study objectives	1. One minute exposure to food odours increases appetite, appetite for the smelled food and salivation, compared to baseline (t=0). 2. Twenty minute exposure to food odours increases appetite and salivation, compared to baseline (t=0), but decreases the appetite for smelled foods. 3. Non-food odours evoke different appetite responses than food odours.
Ethics approval(s)	Medical Ethical Testing Committee (METC), Wageningen University, April 2009, ref: NL35493.081.11
Health condition(s) or problem(s) studied	Obesity
Intervention	Cross-over study with 8 odour conditions: 5 food odours, 2 odours in duplo (repeated two times), two non-food odours and no-odour (duplo). Each participant completed two sessions per day, in total 12 sessions. Twenty minute odour exposure to eight different odour conditions: no-odour (duplo), bread odour, chocolate odour (duplo), banana odour, tomato soup odour, meat odour (duplo), grassy odour and pine tree odour. Exposure to one odour during one session.
Intervention type	Other
Primary outcome measure	1. Appetite (on visual analogue scale) was filled out at baseline and 1, 5 9, 13 and 18 minutes after onset of odour exposure 2. Appetite for smelled foods (on visual analogue scale) was filled out at baseline and 1, 5 9, 13 and 18 minutes after onset of odour exposure 3. Appetite for smelled foods measured with food preference questionnaire was filled out 20 minutes after onset of odour exposure
Secondary outcome measures	Salivation at baseline and 0.5, 4, 8 and 17 minutes after onset of odour exposure
Overall study start date	02/05/2011
Completion date	23/06/2011

Eligibility

Participant type(s)	Patient
Age group	Adult
Lower age limit	18 Years
Upper age limit	45 Years
Sex	Female
Target number of participants	20
Key inclusion criteria	1. Women aged 18-45 years 2. Healthy, based on self report 3. Body mass index (BMI) 18.5-25 kg/m2
Key exclusion criteria	1. Smoking 2. Restrained eater 3. Lack of appetite 4. Dieting for the past 2 months 5. Change in body weight > 5 kg during last 2 months 6. Vegetarian 7. Hyper sensitivity or allergy to any food product 8. Pregnant or breast feeding during last 6 months
Date of first enrolment	02/05/2011
Date of final enrolment	23/06/2011

Locations

Countries of recruitment

Netherlands

Study participating centre

Bomenweg 2

Wageningen
6703 HD
Netherlands

Sponsor information

Technology Foundation STW (Stichting Technische Wetenschappen) (Netherlands)
Research organisation

Postbus 3021
Utrecht
3502 GA
Netherlands

Website	http://www.stw.nl/en
"ROR"	https://ror.org/057tq3593

Funders

Funder type

Research organisation

Technology Foundation (STW) (Netherlands)

No information available

Results and Publications

Intention to publish date
Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not provided at time of registration
Publication and dissemination plan	Not provided at time of registration
IPD sharing plan