In the news: Vitamin D & Multiple Sclerosis; Recent Findings

Multiple Sclerosis: Background

Multiple sclerosis (MS) is a progressive disease of the CNS that affects more than 2.3 million people worldwide, according to the National MS Society. In MS, the immune system attacks the protective lipid-protein myelin sheath that insulates nerve fibers, which interrupts or distorts nerve impulses traveling to and from the brain and spinal cord.

Symptoms, which vary among individuals, are commonly fatigue, weakness, poor balance, lack of muscle control, and vision problems, including optic neuritis, double vision, and nystagmus, or uncontrolled eye movements. Vision problems, in fact, are often the first symptom of MS. 

It’s believed that MS is triggered in genetically susceptible individuals by a combination of one or more environmental factors. Vitamin D deficiency was theorized to be one of those factors in the early 1970’s. Since then, many publications have linked vitamin D insufficiency with MS development, and some research has suggested that adequate status of the vitamin may be protective.

Several recent studies provide insight into the effects of vitamin D on MS progression, immune regulation, and on the risk of deficiency during pregnancy.

Vitamin D May Predict Progression in Early MS

Does vitamin D status predict disease activity and prognosis in early MS? To shed light on this question, Harvard researchers looked at serum levels of vitamin D in 465 participants of a randomized trial originally designed to evaluate the impact of early vs. delayed interferon beta-1b treatment in MS (1). The patients were followed clinically and by MRI for 5 years.

Higher serum levels of vitamin D (25-hydroxyvitamin D, a marker of vitamin D status) predicted a reduction in MS activity and a slower rate of progression. Higher serum levels within the first 12 months predicted a 57% lower rate of new active lesions, a 57% lower relapse rate, a 25% lower yearly increase in inflammatory lesion volume, and a 0.41% lower yearly loss in brain volume.  Similar associations were seen in MS activity or progression from 24 to 60 months, and higher serum vitamin D (> 20 ng/mL) at up to 12 months predicted lower disability during the next 4 years.

Maternal Vitamin D & MS Risk in Offspring 

Using serum samples from the Finnish National Cohort biobank, Harvard researchers compared the maternal vitamin D levels during pregnancy of 176 of their offspring diagnosed with MS, with the maternal vitamin D levels of 326 unaffected children (all 18-27 yrs.) (2).

The children of mothers with vitamin D deficiency during their pregnancy had a 2-fold greater risk of developing MS than those whose mothers were not deficient (< 12.02 ng/mL vs. 12.02 to < 20.03 ng/mL). 

In an accompanying editorial (3), Dr. B.M. Greenberg explained that one mechanism that might explain the link of vitamin D insufficiency with MS is the vitamin’s co-factor role in myelin formation. Deficiency of vitamin D during critical growth periods may create “weak myelin” prone to damage in MS. 

Vitamin D Helps Regulate T-Cells in MS

Another connection between vitamin D and MS focuses on the effect of vitamin D receptor activation on the immune system (4). Vitamin D receptor activation can suppress IL-17, leading to pro-inflammatory T-cells.

A Johns Hopkins team randomized 40 MS patients to receive 10,400 IU or 800 IU vitamin D daily for 6 months, People in the high-dose group had a reduction in the percentage of inflammatory T-cells related to MS severity. These changes weren’t seen with the low-dose.  The researchers concluded that high dose vitamin D is safe for those with MS and may help regulate the body’s hyperactive immune response. Whether the changes in inflammatory T-cells translate to less severe MS is the subject of clinical trials currently underway. 

References

1. Ascherio A., et al. Vitamin D as an early predictor of MS activity and progression. JAMA Neurol. 71:306-14, 2014.
2. Munger K.L., et al. Vitamin D status druing pregnancy and risk of MS in Offspring of women in the Finnish Maternity Cohort.  JAMA Neurol. Mar 7, 2016 [Epub ahead of print].
3. Greenberg B.M., Ed: Vitamin D during pregnancy and MS: An evolving association. JAMA Neurol. Mar 7, 2016 [Epub ahead of print].
4. Sotirchos E.S., et al. Safety and immunologic effects of high vs. low dose cholecalciferol in MS. Neurol. 86:382-90, 2016.