The current role and therapeutic targets of vitamin D in gastrointestinal inflammation and cancer.

Vitamin D, beyond its classical roles in the regulation of calcium and phosphorus homeostasis and bone metabolism, has been implicated in multiple pathological processes, including progression from inflammation to cancer development and also involvement in autoimmune diseases as well as cardiovascular disorders. In this review, we shall discuss the different roles of vitamin D and its therapeutic targets in different gastrointestinal diseases, focusing on colorectal cancer (CRC) and inflammatory bowel disease (IBD). To this end, vitamin D deficiency has been identified as a risk factor of CRC. On the other hand the active metabolite of vitamin D, 1, 25- dihydroxyvitamin D3 (1, 25(OH)2D3) has multiple anti-cancerous benefits including inhibition of proliferation, induction of apoptosis, promotion of differentiation and suppression of angiogenesis in tumors. In IBD, vitamin D is involved in the pathogenic process through the normalization of immune responses in the colon. With these experimental findings, well-designed and large-scale clinical trials are warranted to further define the therapeutic action of vitamin D in the prevention and/or treatment of IBD and further on CRC in humans.