MS is associated closely with lack of sun exposure and low vitamin D levels. So what is new? By Marc Sorenson, EdD
MS is a disabling autoimmune disease.
MS is an autoimmune disease in which T-cells initiate an inflammatory response against myelin. This process, known as demyelination, leaves the nerves bare and susceptible to “short circuiting.” As a result, communications between brain and body suffer damage. Eventually, the disease causes irreparable deterioration of nerves. Some of the effects of MS include numbness and weakness in limbs. In addition, there may be lack of coordination, loss of vision, lack of mobility, slurred speech and numerous other disorders.
What do we know about the connection between sun exposure and MS?
Sunlight is an immunomodulator. In other words, it may affect the functions of the immune system. In the case of an autoimmune disease, it may stop the immune system’s attack on its own tissue. Because sunlight stimulates the production of vitamin D in skin, it may suggest that vitamin D is protective. In addition, it also suggests the incidence should diminish in areas of high sun exposure, and increases in areas of low exposure.
Thus, the risk of MS in far northern areas is 100 times greater than in equatorial areas.
In equatorial areas, sunlight is intense, and the risk of the disease approaches zero. Another interesting study of immigrants to the UK (low sunlight), but born in the sunny West Indies is enlightening. Especially relevant is that these immigrants had one-eighth the rate of MS as their own children born in the UK. It therefore appears that childhood sun exposure provides protection against the disease.
Where does vitamin D fit?
While it is tempting to chalk up the association of low MS to high vitamin D (as mentioned above), use caution. As with certain other diseases, sun exposure may have a positive influence on MS, independent of vitamin D. For example, a study on animals assessed the relative affect of sunlight and vitamin D on the diseaase. The researchers concluded, “These results suggest UVR [sun] is likely suppressing disease independent of vitamin D production.” They also stated that vitamin D supplementation alone might not replace the ability of sun (UV) to reduce MS susceptibility.
The investigators used animals that had no vitamin D receptors (VDR), and therefore could not produce vitamin D. Therapy with UV light suppressed the disease. The investigators concluded that UV light suppression of MS occurs in the absence of vitamin D production.
Another recent investigation: High sun exposure and high vitamin D both associate with lessened severity of MS.
This study investigated the severity of the disease among people who already had MS. Thus, it was a unique study, to my knowledge. The investigators used the subjects’ latitude (a marker for sun exposure and vitamin D levels) and compared it to MS severity. Interestingly, high sun exposure and high vitamin D levels associated to a reduction in MS severity. However, the investigators listed only sunlight as a sure factor in reducing MS severity.
Hence, the investigators stated three salient points in their paper.
- “Observational studies suggested vitamin D-dependent effects, but prospective supplementation studies have so far been inconclusive….”
[This is an important, and a wake up call. Those who believe that we need only swallow a handful of pills, as we avoid the sun, are sadly mistaken. There is no way we can determine if high vitamin D blood levels are the reason for a reduction in MS severity. That is, unless we produce those levels in a scientific, controlled study using supplementation.]
- “Although [low] vitamin D cannot be proven as the causal factor, we provide evidence for clinically relevant effects of sunlight exposure.
- ”Furthermore, this study suggests sunlight triggered pathways other than vitamin D could play additional and modulatory roles as well.”
There you have it.
High sunlight exposure decreases the severity of multiple sclerosis. Vitamin D, though it is a miraculous nutrient, probably has little or no effect on the disease.