what is the real fate of vitamin d in multiple sclerosis?

multiple sclerosis (ms) is a multifactorial disease (caused by both environmental and genetic features) that could results from a demyelination of the myelin sheath. subsequently, it leads to many scars or lesions in different places within the central nervous system. the symptoms that occur depend on the site and rigorousness of the lesions and this is why people with ms experience different symptoms. although, it is not clearly known that why people develop ms, research suggests that vitamin d plays a key role in preventing or repairing the damaged myelin. previous studies have shown that vitamin d is a potent natural immune‑regulator and has an anti‑inflammatory action. increased exposure to vitamin d may result in changed immunologic profiles or commotion that donates to ms risk. vitamin d deficiency is caused by insufficient sunlight exposure or low dietary vitamin d3 intake. recent studies have also indicated that, there are several polymorphisms for vitamin d receptor (vdr) gene, but the effect of vdr gene polymorphisms on protein function of vdr and how exerts second signaling pathways in cells is still unknown. therefore, this review focuses on vitamin d metabolism and genetic polymorphisms related to vdr and ms to better understand of discrepancies among patients.