Purpose: The aim of this study is to investigate in a population of adolescents living in Regione Campania, undergoing sun exposure at least 9 months per year the prevalence of severe deficiency (<20 ng/ml) or insufficiency (21-29 ng/ml) of 25-Hydroxyvitamin D (25(OH)D) levels and its relationship with individual body weight, use of smoking, and exercise performance.
Methods: From October 2012 to October 2013, 373 healthy subjects (153 girls, 223 boys 11-20 years) without chronic diseases were consecutively enrolled in a campaign to prevent metabolic, cardiovascular, and oncological diseases. 25(OH)D assay, BMI, and lifestyle habitudes (smoking and exercise indoor or outdoor) were assessed.
Results: In this population, median 25(OH) level was 25.0 ng/ml (95 %CI 23.8-25.2) without any difference between girls (25.0 (95 %CI 23.1-25.7)) and boys (24.3 (95 %CI 23.8-25.2)). Severe deficiency was found in 6 girls (0.02 %), while insufficiency was found in 296 patients (110 girls, 79.3 %). Normal levels were found in 71 patients (37 girls, 19 %). Vitamin D levels were significantly correlated with BMI (r = -0.429, p < 0.0001), smoking (r = -0.241; p < 0.0001), and exercise performance (r = 0.791; p < 0.0001). At the multistep regression analysis, Vitamin D levels were best predicted by exercise performance (t = 19.6, p < 0.0001), less smoking addiction (t = -4.97, p < 0.001), and lower BMI (t = -4.69, p < 0.0001).
Conclusions: The current study demonstrates that Vitamin D levels are commonly unsatisfactory in adolescents. Lower levels were found in overweight or obese adolescent, smokers and with low or absence of physical activity outdoors.