Safety and T cell modulating effects of high dose vitamin D3 supplementation in multiple sclerosis.

BackgroundA poor vitamin D status has been associated with a high disease activity of multiple sclerosis (MS). Recently, we described associations between vitamin D status and peripheral T cell characteristics in relapsing remitting MS (RRMS) patients. In the present study, we studied the effects of high dose vitamin D3 supplementation on safety and T cell related outcome measures.Methodology/principal findingsFifteen RRMS patients were supplemented with 20,000 IU/d vitamin D3 for 12 weeks. Vitamin D and calcium metabolism were carefully monitored, and T cell characteristics were studied by flowcytometry. All patients finished the protocol without side-effects, hypercalcaemia, or hypercalciuria. The median vitamin D status increased from 50 nmol/L (31-175) at week 0 to 380 nmol/L (151-535) at week 12 (PConclusion/significanceTwelve week supplementation of high dose vitamin D3 in RRMS patients was well tolerated and did not induce decompensation of calcium metabolism. The skewing towards an anti-inflammatory cytokine profile supports the evidence on vitamin D as an immune-modulator, and may be used as outcome measure for upcoming randomized placebo-controlled trials.Trial registrationClinicaltrials.gov NCT00940719.