Nickan Research Institute Journal of Parathyroid Disease 2345-6558 2 1 2014 01 01 Vitamin D deficiency in children and adolescents; an international challenge 27 31 EN Zahra Taheri Mahin Ghafari Abdollah Hajivandi Masoud Amiri Journal Article Low vitamin D level is an important international public health problem. Vitamin D deficiency and its consequences among children and adolescents could indeed be considered as one of the most important public health problems. In fact, low vitamin D levels were reported in both children and adolescents. Several reasons could be taken into account in this regard such as the possibility of the reduced intake or synthesis of vitamin D (due to having a vitamin D deficient mother or a dark skin color), abnormal intestinal function or malabsorption (in small-bowel disorders), or reduced synthesis or increased degradation of vitamin D (in chronic liver or renal disease). More importantly, many countries in developing world, are experiencing a substantial percentage of adolescent and youth population with their own health related problems which vitamin D deficiency could affect on their health. The association between obesity and overweighting and vitamin D deficiency has been reported by many researchers. Diabetes mellitus has also an association with vitamin D deficiency, for both type 1 and type 2 diabetes. Due to the importance of vitamin D deficiency and its negative health consequences, taking the vitamin D supplement seems to be necessary