The Role of Vitamin D in Gastrointestinal Diseases: Inflammation, Gastric Cancer, and Colorectal Cancer

Vitamin D as a prohormone is converted into the active form in vivo and binds to vitamin D receptors, exercising a wide range of biological functions. Recent studies strongly support that vitamin D supplementation is associated with reduced cancer risk and a good prognosis. Gastrointestinal cancer is the leading cause of cancer-related deaths worldwide. The key role of vitamin D in the development of gastrointestinal cancer has been observed. Moreover, Vitamin D can also affect innate immunity and perform anti-inflammation and anti-infection actions. Given the intimate relationship between cancer and inflammation, we herein summarize epidemiological and preclinical studies of vitamin D and the underlying mechanism of its action in inflammation, gastric and colorectal cancer by our group and other researchers. A beneficial effect of vitamin D in cancer and inflammatory disease has been supported by different studies. More controlled and larger clinical trials are needed before a reliable conclusion and realization of vitamin D supplementation in the adjunct treatment of gastrointestinal inflammation and cancer.