5. Conclusions
toddlers
VD supplementation in doses of 400 IU (D2), 800 IU (D2), and 1000 IU (D3) per day, five times per week for three months, was effective in increasing serum 25(OH)D concentrations and reducing VD deficiency in children 12–30 months of age. The highest efficacy was observed by giving 1000 IU/day D3. Our study adds to the evidence of the effect of VD supplementation on VD status and in the prevention of VD deficiency among toddlers and preschool children, which has long-term benefits for bone health, growth, and other important health-related outcomes at this early stage of the life cycle. More studies are needed to assess these effects in this age group.