Researchers wishing to evaluate the safety profile and characterize the immunologic effects of high dose vs low dose cholecalciferol (vitamin D3) supplementation in patients with MS, conducted a double-blind, randomized study of 40 patients with relapsing-remitting MS. Patients received 10,400 IU or 800 IU of D3 daily for 6 months. Assessments were conducted at baseline, 3 and 6 months. Results showed a mean increase of 25(OH)D levels was greater in the high dose group vs the low dose group. In the high dose group only, they found a reduction in the proportion of interleukin-17+CD4+ T cells, CD161+CD4+ T cells, and effector memory CD4+ T cells with concomitant increase in central memory CD4+ T cells and naïve CD4+ T cells. In other words, as the levels of vitamin D increased, there was a corresponding decrease in the levels of CD4+ T cells and interleukin-17, a protein they create which is pro-inflammatory. The researchers concluded that vitamin D3 supplementation with 10,400 IU daily is safe and tolerable in patients with MS and exhibits in vivo pleiotropic immunomodulatory effects in MS.
Sotirchos ES, et al. Safety and immunologic effects of high-vs low-dose cholecalciferol in multiple sclerosis. Neurology. 2015