Prof Kees De Graaf
Division of Human Nutrition
PO Box 8129
ABR form NL 25334.081.08
The effect of choice-offering on children's vegetable consumption: a between-subject randomised controlled trial
We hypothesise that children's vegetable liking and consumption will be higher in the choice-offering condition compared to the no-choice condition.
The Medical Ethical Committee of Wageningen University approved on the 16th December 2008 (ref: 08/20)
Multicentre between-subject three-arm randomised controlled trial
Primary study design
Secondary study design
Randomised controlled trial
Quality of life
Patient information sheet
Not available in web format, please use the contact details below to request a participant information sheet
Healthy eating in children and related health status
Three treatments during a dinner situation:
1. No-choice condition: the child is not allowed to choose; the child is randomly assigned one of the two target vegetables
2. Choice-condition: the child is allowed to choose which of the two target vegetables he or she wants to eat for dinner
3. Variety-condition: the child receives both target vegetables for dinner
Duration of treatment per participant for each arm/condition = 1 day; no follow-up.
Primary outcome measures
Vegetable consumption: consumption will be assessed by subtracting the amount of vegetable left on the plate from the pre-weight, measured after the intervention (post-treatment).
Secondary outcome measures
1. Liking of the vegetables: the children will make a preference rank order for various vegetables, with the use of three categories (smileys) of liking. This preference rank-order will be performed twice. The first time is before the start of the study at school, in order to select the target vegetables. The second rank-order will be performed at the Restaurant of the Future, after the meal, to assess how the offering of the vegetables influences the pleasantness of the vegetables. We focus on the vegetable that the child ate (choose self versus no choice), but also for the vegetable that the child had seen but was not allowed to eat (choose self versus no choice). Measured before and after the intervention (pre + post- treatment).
2. Perceived choice and autonomy: to be able to check if the children experienced more choice when they were in a choice condition, we will ask the children and their parents a few questions related to choice and autonomy (Based on Intrinsic Motivation Inventory). Measured after the intervention (post-treatment).
3. Intrinsic motivation, reactance and experience of meal context: various questions will be asked to understand the process of reactance, the whole meal experience and children's intrinsic motivation. For the children, these questions will be very simple and concrete, so they can answer them reliably. The answers of the parents may help us understand how the child and his/her parent experienced the situation (Based on Intrinsic Motivation Inventory). Measured after the intervention (post-treatment).
4. Consumption of the other meal components: the consumption of potatoes and meat can influence children's vegetable consumption. Consumption will be measured by weighing before and after the meal. Measured after the intervention (post-treatment).
5. Parental consumption: we will measure parental consumption of potatoes, meat and vegetables as a measure of modelling: do parent and child eat similar portions? Do they finish the same items on the plate? Measured after the intervention (post-treatment).
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Healthy children aged 4 - 6 years old (girls and boys) and their parents
2. Children whose parents signed an informed consent
3. Parents who gave their consent to participate
Target number of participants
Participant exclusion criteria
1. Children without signed informed consent of their parents
2. Children with vegetable allergy
3. Children who refuse to eat target vegetables of the study
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Wageningen University (Netherlands) - Graduate Schools VLAG and Graduate School Mansholt
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Results - basic reporting
2010 results in http://www.ncbi.nlm.nih.gov/pubmed/20007305
Zeinstra GG, Renes RJ, Koelen MA, Kok FJ, de Graaf C, Offering choice and its effect on Dutch children's liking and consumption of vegetables: a randomized controlled trial., Am. J. Clin. Nutr., 2010, 91, 2, 349-356, doi: 10.3945/ajcn.2009.28529.