The influence of diet and physical activity on bone density of children aged 5–7 years: The Belfast HAPO family study

•The aim was to explore the influence of diet and physical activity on bone mineral density (BMD) of children aged 5-7 years.•Neither dietary vitamin D/calcium intakes were significantly associated with child heel BMD or BMAD in multiple regression.•Physical activity was associated with better BMD and BMAD in 5–7-year-old children.•More research is needed regarding blood concentrations of vitamin D and calcium to determine association with BMD.