Endocrine Abstracts

Background: Vitamin D deficiency has been associated with a wide range of chronic diseases, including childhood obesity. Prevalence of vitamin D deficiency in obese children and adolescents ranges from 6.5% to 57% depending on the population and criteria.

Subjects and methods: This cross-sectional clinical study included 92 obese patients with BMI z score <2 and 39 healthy normal-weight subjects in the control group who were matched with the study group in terms of age, gender and pubertal status. Anthropometric assessment and fasting 25-hydroxyvitamin D (25(OH)D were measured. Obese subjects were dived in two groups depending on the presence of metabolic syndrome (MS), which was defined by IDF criteria. Adherence to the Mediterranean diet was assessed by Mediterranean Diet Quality Index for children and adolescents (KIDMED index), while physical activity was evaluated by Physical Activity Questionnaire (PAQ).

Results: Serum levels of 25(OH)D were significantly lower in obese subjects compared to the control group (52.0±17.93 vs. 64.09±25.82 nmol/l, P=0.003). After an additional stratification regarding the presence of MS and subsequent comparison to the control group, analysis showed that subgroup of obese patients with MS had significantly lower levels of serum vitamin D (46.99±17.11 vs. 54.58±17.93 vs. 64.09±25.82 nmol/l, P=0.003). Obese patients with MS had lower PAQ score when compared to obese without MS and the control group (2.32±0.55 vs. 2.49±0.67 vs. 2.85±0.63 nmol/l, P=0.002), while no significant differences were observed in KIDMED index (4.23±1.81 vs. 4.21±2.13 vs. 4.87±2.29, P=0.251), respectively. Serum levels of 25(OH)D showed significant and negative correlation with BMI z score (r=−0.208, P=0.017) and positive correlation with PAQ score (r=0.305, P<0.001) in both control and obese subjects.

Conclusions: In conclusion, this study demonstrated that obese children and adolescents had significantly lower values of serum 25(OH)D and lower adherence to physical activity compared to healthy controls. The positive correlation between vitamin D and the degree of physical activity points to the importance of physical activity in the prevention of further cardiovascular complications. However, additional studies with long term follow-up are needed to further clarify the impact of physical activity on the status of vitamin D in obese children and adolescents.