Vitamin D supplementation in young children: associations with Theory of Planned Behaviour variables, descriptive norms, moral norms and habits.

Objective: In the Netherlands, a supplementation of 10 microg vitamin D is recommended for children (aged 0-4 years), given that vitamin D contributes to the development of healthy bones and deficiency during childhood is a risk factor for osteoporosis at a later age. However, only 60 % of the Dutch children receive sufficient vitamin D supplementation a day. In order to develop interventions to improve supplementation intake, it is necessary to gain insight into the behaviour of parents in giving their children vitamin D supplementation and its association with variables of the Theory of Planned Behaviour, moral and descriptive norms and habits.