The aim of this study was to determine the prevalence of vitamin D deficiency among preschool children in rural and urban areas of Northern Iran and need for continuing vitamin D supplementation after 2 years of age.
A sample of 406 children aged 30–72 months was selected from health centres. Serum levels of 25-hydroxyvitamin D (25OHD), demographic data, anthropometric characteristics and total body surface area, were evaluated.
Subnormal vitamin D levels were found in 68.94% (269) of children. In multiple logistic regression models, season (P = 0.001) and residency (P = 0.006) were significantly correlated with vitamin D deficiency. Multiple linear regression analysis revealed that age (β = −0.18, P < 0.001), body mass index (β = −1.1, P < 0.001) and sun exposure (β = 0.4, P < 0.001) were significantly associated with 25OHD level.
Owing to the high prevalence of subnormal vitamin D levels in preschool children, it is recommended that vitamin D deficiency prevention programs are continued in this age group.