Cooking together: The IKEA effect on family vegetable intake

Based on the idea of the 'IKEA effect', assuming that individuals like self-created objects more than objects created by someone else, this study hypothesizes that parents' involvement of their children in meal planning and preparation is positively related to vegetable intake, mediated via liking vegetables.

Longitudinal observational study with two time points (10-month interval).

Nine hundred and twenty-four parent-child dyads filled out questionnaires measuring involvement, vegetable liking, vegetable intake, and further environmental and food-related determinants of vegetable intake. On average, parents were M = 36.10 (SD = 5.43) and children (54.3% girls) M = 8.24 (SD = 1.44; range 6-11) years old. Hypotheses were tested with path analyses, accounting for intra-dyadic associations among respective constructs (e.g., parents' and children's liking vegetables).

Two direct effects were found: (1) parents' involvement of their children in cooking activities impacted children's liking of vegetables and vegetable intake, and (2) liking vegetables impacted vegetable intake. The effect of involvement on vegetable intake was mediated via liking vegetables, but only for children and not for parents.

The findings emphasize the importance of parents' encouragement for involving children in the preparation of healthy meals, as this improves liking of vegetables and, thereby, increases their vegetable intake. Statement of contribution What is already known on this subject? Processes behind the effectiveness of shared cooking activities to increase vegetable intake are unclear. Previous research suggests the IKEA effect as an explanation. It assumes a higher consumption of self-created products due to a higher liking compared to third-party products. What does this study add? First test of the IKEA effect for joint cooking activities under consideration of spillover effects in families. Affirmation of the IKEA effect was found for children, not for parents. Interventions should focus on the involvement of children in cooking activities to improve vegetable intake.