Customizing Nutrients: Vitamin D and Iron Deficiencies in Overweight and Obese Children—Insights from a Romanian Study

<b>Background</b>: Childhood obesity is a public health issue worldwide, recognized as a complex condition associated with multiple deficiencies in nutrients, such as vitamin D deficiency, iron-deficiency anemia, or abnormalities in serum calcium or phosphorus levels, despite an excess caloric intake. <b>Objective</b>: This study aims to investigate the prevalence of these deficiencies in overweight/obese children and to assess the correlation between vitamin D/serum iron levels and body mass index (BMI). <b>Methods</b>: The observational study was conducted on 69 Romanian overweight and obese children, aged 2 to 17, admitted to the Pediatrics Department of "Grigore Alexandrescu" Hospital in Bucharest over a 15-month period. The age- and gender-specific BMI percentiles were used to classify participants into three groups: overweight (≥85th and <95th BMI percentile), obese (≥95th BMI percentile), and severely obese (>120% of 95th BMI percentile). Data analysis focused on identifying the need for screening and targeted treatment in this pediatric population. <b>Results</b>: Hypovitaminosis D (defined as a serum level of 25(OH)D < 30 ng/mL) prevalence was significantly higher in the severe obesity category (71.5%) compared to the obesity (69%) and overweight (61.5%) groups. Iron deficiency and iron-deficiency anemia were both more prevalent in overweight children, with rates of 50% and 38.5%, respectively. Negative moderate correlations were found both between serum 25-hydroxyvitamin D levels and children's age (r = -0.444, <i>p</i>-value < 0.0001), as well as between serum 25(OH)D levels and BMI (r = -0.31, <i>p</i> = 0.015), with no statistically significant correlation between serum iron level and BMI in this cohort (r = -0.02, <i>p</i> > 0.05). <b>Conclusions</b>: Severe obesity could be regarded as an associated factor for vitamin D insufficiency as this is highly prevalent in severely obese children, with 25(OH)D levels decreasing with the increase in BMI. Overweight children demonstrated an increased prevalence of iron deficiency in the overweight category, suggesting that the adipose tissue contributes to chronic inflammation, disrupting iron homeostasis. Given the high prevalence of nutritional deficiencies in this population, implementing systematic screening and treatment programs would be beneficial to prevent long-term adverse outcomes.