How is vitamin D deficiency different from MS and what is the chance of being diagnosed with MS when the actual cause is vitamin D deficiency?
The main difference between MS and vitamin D deficiency is that MS is defined as recurrent inflammation in the central nervous system while vitamin D deficiency is simply defined as a low blood level of circulating vitamin D. In isolation, vitamin D deficiency is not MS. Current knowledge, however, suggests that vitamin D deficiency may influence inflammatory disease already present in an individual (MS being one of many such conditions).
MS is considered a complex trait—meaning that various environmental and genetic factors play a role in who is susceptible to developing the disease. Vitamin D, interestingly, may play a role in both environmental AND genetic susceptibility to MS. The environmental component would be where you live (ie, what latitude influences time of exposure to sunlight), how much sun exposure you get (as our skin produces active vitamin D from exposure to sunlight), and the amount of vitamin D you consume in your diet (including supplementation with vitamin D3 or cholecalciferol). The genetic component is beginning to become more apparent through research efforts.
Based on our current knowledge on this topic, the relationship between vitamin D and MS is one of association and has not been proven to be one of causation (ie, vitamin D deficiency does not cause MS by itself). We have observed that patients with MS who are vitamin D deficient on average have more active MS—defined as more MRI lesion activity and a greater frequency of MS relapses—compared with MS patients who have normal vitamin D levels. The fact that there are vitamin D receptors on lymphocytes (white blood cells) and their function appears to be in influencing how inflammatory the immune system is, further strengthens the argument that vitamin D status and MS disease activity are related. Currently, interventional clinical trials (comparing high and low dose vitamin D) are underway to determine if low vitamin D levels and MS disease activity is really a “cause and effect” relationship.
The diagnosis of MS requires that other mimicking diseases of MS are reasonably excluded or ruled out. Vitamin D deficiency is not one of these mimickers. The question of vitamin D deficiency is if we should be repleting patients with MS with the hope that doing so will reduce the number of new or enhancing brain and spinal cord lesions and clinical relapses in the future. Supplementation should be discussed with your physician. I would also caution readers that supplementing with vitamin D should not replace treatment with an FDA approved MS therapy. The current scientific evidence does not support such an approach.
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