Vitamin D Deficiency in Kazakhstani Children: Insights from a Systematic Review and Meta-Analysis.

Background and Objectives: Kazakhstan's unique geographic, dietary, and cultural factors contribute to the widespread occurrence of vitamin D deficiency across the entire country population, particularly among children. This study aims to assess the mean prevalence of vitamin D deficiency in children in Kazakhstan and determine whether it differs between healthy and non-healthy children, as well as between infants and older age groups. Materials and Methods: A comprehensive literature search was performed across five databases by two researchers. Studies were eligible if they were observational and provided the number of children with serum 25-hydroxyvitamin D levels below 20 ng/mL out of the total number of children assessed in Kazakhstan. Results: Eleven studies were included in the analysis, assessing 1396 children, of whom 714 had the outcome of interest. The pooled mean estimate of vitamin D deficiency among children was 56% (95% CI, 46-65%), with particularly concerning rates among infants at 65% (95% CI, 44-82%). No substantial differences were observed between healthy and non-healthy children. Conclusions: The prevalence of vitamin D deficiency among children is alarmingly high. These results highlight the urgent necessity of tackling vitamin D deficiency as a public health priority. Incorporating vitamin D deficiency prevention into Kazakhstan's national healthcare program is vital for improving child health outcomes and reducing the long-term burden of associated complications.