Vascular and Metabolic Effects of Vitamin D Supplementation Associated With Lifestyle Management in Obese Adolescents

The main objective of this study is to analyze in a population of obese adolescents, the effect of vitamin D3 supplementation in addition to lifestyle and dietary management on vascular function assessed by the change between M0 and M3 of endothelium-dependent vasorelaxation measured at the brachial artery (Flow-Mediated Dilation).

The secondary objectives of this study are: A. To analyze in obese adolescents, the effect of the addition of vitamin D3 supplementation on metabolic and vascular function. B. To compare the relationships between food intake, metabolic, inflammatory, oxidative stress and vitamin D status, and vascular dysfunction between obese and normal weight subjects. C. To evaluate the effects of sun exposure variations on relationships described in Objective B by comparing the observed parameters at baseline and at the end of the three month follow-up period, in non-supplemented obese adolescents and adolescents of normal weight. D. To identify biomarkers (metabolic signatures) in obese adolescents associated with vitamin D deficiency and vascular function. E. To evaluate in obese adolescents, the effects of vitamin D supplementation on the metabolome (metabolic signature). F. To evaluate the effects of lifestyle and dietary management on these biomarkers (in the "control group"). For these targets (A to F), all teenagers will be classified according to three levels of skin pigmentation. G. Establish a biobank of samples taken at baseline and at 3 months.