Vitamin D (calciferol), i.e. its active metabolite calcitriol [1,25(OH)2D], apart from essential participation in calcium and phosphorus homeostasis, is an important factor in the regulation of cell proliferation, differentiation and apoptosis, angiogenesis, immune and hormonal activity and other processes in the human body. Hence, its optimal balance is extremely important for adequate prenatal and postnatal growth and development, as well as for the preservation of health in other phases of life. This article provides a brief overview of the natural sources of vitamin D, its metabolism and physiological role, as well as current recommendations related to the coverage of its optimal needs.