by Jaime Johnson

Created on: January 09, 2007   Last Updated: April 03, 2007

Multiple Sclerosis (MS) is a disease currently affecting 350,000 Americans and is characterized by a degeneration of the nervous system3. It is an autoimmune disease, where the body's own immune cells attack the myelin sheath covering the nerves. The breakdown of the myelin sheath causes lesions in the brain and subsequent erratic firing of the nerves. MS can be progressive or remissive/progressive, characterized by flares (an increase in symptoms) interspersed with periods of relatively few symptoms. As the body attacks itself, it can lead to a host of problems, from fatigue and muscle weakness, to inability to tolerate heat and vision problems, in addition to the more crippling aspect of the disease as it progresses.

As with other autoimmune diseases, it is not clear what causes MS, but it seems to be due to both genetic and environmental causes. MS is more prevalent in females than males, with a 3:1 ratio3. One trend that has been observed in the onset of MS is that there are very few cases of MS at equatorial locations and the incidences of MS increase with increasing latitudes, with the highest number of cases being reported in Scandinavian countries1,2,7. This finding has led researchers to investigate the link between vitamin D deficiency and autoimmune diseases.

Vitamin D is made in the skin, when exposed to the UVB radiation in sunlight. Vitamin D has also been shown to function as an immune system regulator4. In its active form in the blood stream (25(OH)2D3), vitamin D has been shown to reduce the production of inflammatory cytokines, in particular Il-12, which may be responsible for causing the lesions on the nerves seen in MRI's of MS patients5,8.

Seasonal studies with MS patients have shown a trend that there are more lesions visible in MRI scans in the spring than in the fall4. Due to the angle of the earth in the winter, the UVB rays needed to make vitamin D are refracted off of the atmosphere, leading to increased deficiency during the winter months. This has led researchers to investigate whether or not vitamin D supplementation can benefit those already suffering from MS, as well as being a preventative measure.

Many MS patients have low blood levels of the active form of vitamin D2,6. The recommended dosage by the USDA is currently at 20 ng/mol (or 400 IU), although many specialists now believe this limit is too low1,2,7. A general survey done in the US examining dietary vitamin D intake, shows that a good portion of the US is not meeting USDA

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