VDR and vitamin D deficiency: Therefore, 1,25(OH)2D could have a preventive effect on adverse conditions via binding at the vitamin D receptor and, vice versa, vitamin D deficiency and insufficiency may act as risk factors for several chronic diseases, including osteoporotic diseases [9,10], cardiovascular diseases (CVD) [11], diabetes mellitus [12], several types of cancer [13], infections [14] and several auto-immune conditions [15].