Vitamin D in health and disease

Abstract

Vitamin D is the precursor of the steroid hormones 1,25-dihydroxy-vitamin D (1,25(OH)2D). Most of the biological effects of 1,25(OH)2D derive from its interaction with vitamin D receptor (VDR), an intracellular transcription receptor. VDR regulates genes that influence bone mineral homeostasis, immunomodulation, insulin secretion, cell cycle and the detoxification of exogenous and endogenous compounds. The most investigated function of 1,25(OH)2D is the regulation of calcium and phosphate homeostasis and, in turn, the bone turnover rate in skeletal tissue. Recently, also the extra-osseous activity of 1.25 (OH) 2D has received increasing attention. Nevertheless, the lack of definition of optimal status and dosage of vitamin D limits the knowledge derived from available studies and highlights the need for further studies on these topics.