Vitamin D Deficiency in Childhood Obesity: Behavioral Factors or Altered Metabolism?

Abstract

Obesity childhood is related to vitamin D deficiency, but the mechanisms for this association still remain questionable. We hypothesized that behavioral factors would be decisive in reducing the body content of vitamin D in patients with obesity. A cross-sectional clinical and analytical study (calcium, phosphorus, calcidiol, and parathyroid hormone) was carried out in a group of 377 patients with obesity (BMI-DS >2.0), 348 patients with severe obesity (BMI-DS >3.0), and 411 healthy children. The place of residence was categorized as urban or rural. Vitamin D status was defined according to the US Endocrine Society criteria. The prevalence of vitamin D deficiency was significantly higher (p < 0.001) in severe obesity (48.6%) and obesity groups (36.1%) than in the control group (12.5%). Vitamin D deficiency was more frequent in severe obesity and obesity groups living in urban areas than in those living in rural areas (not in the control group). The patients with obesity living in urban residence did not present significant seasonal variations in vitamin D deficiency throughout the year in contrast to those patients with obesity living in rural residence. These findings suggest that the most probable mechanism for vitamin D deficiency in children and adolescents with obesity, rather than altered metabolic, is the behavioral factors (sedentary lifestyle and lack of adequate sunlight exposure).