OBJECTIVETo study the relationship of serum 25-hydroxyvitamin D [25-(OH)D3] level with obesity and inflammatory cytokines in children, and to provide a basis for clinical evaluation of the relationship between vitamin D nutritional status and obesity.

METHODSSeventy-eight children with obesity who visited the hospital between February and June 2012 were selected as subjects. According to baseline data, such as age and sex, 105 children who underwent physical examination in the same period were selected as controls. Fasting venous blood samples were taken to measure serum levels of 25-(OH)D3, interleukin-6 (IL-6), interleukin-8 (IL-8), interferon-γ (IFN-γ), and tumor necrosis factor α (TNF-α).

RESULTSSerum 25-(OH)D3 levels were significantly lower in the obesity group than in the control group (P<0.01). Serum 25-(OH)D3 levels were negatively correlated with BMI (r=-0.462, P<0.01). Patients were further divided, according to their serum 25-(OH)D levels, into vitamin D sufficiency, vitamin D insufficiency, vitamin D deficiency and severe vitamin D deficiency subgroups. There were significant differences in serum IFN-γ levels among the subgroups (P<0.05). There were no significant differences in serum IL-6, IL-8 and TNF-α levels between the subgroups, however (P>0.05).

CONCLUSIONSObese children have lower serum 25-(OH)D3 levels than normal children. Serum 25-(OH)D3 level is negatively correlated with BMI, but has little correlation with inflammatory cytokines levels.