Links Between Vitamin D Deficiency and Multiple Sclerosis

A large body of research suggests that vitamin D deficiency may play a causative role in the development of multiple sclerosis.

In a review paper recently published by the British Journal of Pharmacology, Yeh Wei Zhen of Monash University in Melbourne, Australia, and colleagues provided a detailed overview of the possible connection and the immunoregulatory effects and therapeutic potential of vitamin D in multiple sclerosis. Here is some of what they said:

• There is a latitudinal gradient to MS prevalence and incidence whereby the greater the distance from the equator, the greater the prevalence and incidence. Exposure to ultraviolet B light and vitamin D levels
• Among the adaptive immune cells, which include B and T lymphocytes, vitamin D pushes differentiation toward regulatory B and T cells, which, in turn, ramps anti-inflammatory cytokine production such as IL-10 and TGF-beta and dials down pro-inflammatory cytokines. Inflammatory processes are involved in the demyelination process that characterizes multiple sclerosis.
• A nested case-control study of more than 7 million U.S. military personnel founded that among whites, every 50 nmol/L increase in serum 25 (OH)D3 was associated a 41% decrease in subsequent MS diagnosis. Among blacks, a smaller decrease of 34% was detected.
• A prospective study of Finnish women found that a 50 nmol/L higher level of serum 25 (OH)D₃ during the first trimester of pregnancy reduced later MS risk by 39%.
• Findings from the Nurses’ Health Study and its companion study, Nurses’ Health Study II, have shown an association between total vitamin D intake and the risk of developing multiple sclerosis later on.
• Several studies have shown that low serum vitamin D levels are associated with a higher risk of developing full-fledged multiple sclerosis among those with a first demyelinating attack, sometimes called clinically isolated syndrome. For example, an Italian study found those in lowest 10th percentile of vitamin D among a group of 100 people with clinically isolated syndrome were most likely to convert to clinically definite multiple sclerosis.
• A number of genes that are associated with a higher risk of developing multiple sclerosis are modulated by vitamin D. The researchers mention several genes in this context, including the HLA-DRB1 gene, which has a variant, DRB1*15:01, which they say is the strongest genetic risk factor for MS.
• Several studies have shown a connection between vitamin D supplementation and increases in anti-inflammatory cytokines IL-10 and TGF-beta, but the supplementation story is a mixed bag with different studies coming up with different results.
• Similarly, the results are mixed from studies that have looked at the effects of vitamin D supplementation on multiple sclerosis among those who already have the disease. For example, one placebo-controlled study found evidence of an improvement in MS lesions among those randomized to daily 14,007 IU of vitamin D, but the study’s primary outcomes of relapses, disability progression, or new lesions were not met. Two meta-analyses published in 2018 concluded that there was no significant benefit from vitamin D supplementation.
• “Mixed results” is also the verdict from handful of studies that have tested whether vitamin D supplementation would lessen the chance of people converting from clinically isolated syndrome to multiple sclerosis.