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 guidelines for vitamin D intake, with women between the ages of 15-40 being the most at risk for being deficient3. As vitamin D is not naturally occurring in food, people obtain vitamin D through sunlight, fortified foods such as milk, or through supplements.
In laboratory experiments, mice with an experimental model of MS called EAE, that were given a D deficient diet had more lesions than those on a balanced diet. They also gave vitamin D and calcium supplements to EAE mice and were able to completely halt the disease progression8.
In another study, MS patients were given vitamin D supplements and followed over a course of 1-2 years5. Researchers then examined the patient's cytokine profiles, which are markers for the inflammatory response causing lesions in the brain, and their vitamin D levels. The vitamin D supplementation showed an increase in circulating 25(OH)2D3 levels and a decrease in the cytokines in the MS patients, which may be beneficial in moderating the disease progression. More work needs to be done, however it does appear there is a beneficial, immune regulating effect of vitamin D in MS patients.
The recommended dosage of vitamin D is currently at 400 IU a day, or 20 ng/mol of 25(OH)2D3 in the blood stream. However many doctors feel this level is too low. This is the level set for bone health many years ago, and in light of new information and the effect of vitamin D on the immune system, many believe that for optimum health the blood level of vitamin D should be around 50-75 ng/mol7,8. This would correlate to 1000 IU supplementation a day, or about 15 minutes of sun on exposed arms and legs per day.
Whenever a change in diet or exercise is undertaken, it should be done with caution and under the care of a physician. Vitamin D toxicity can lead to hypocalcaemia, although this is only induced through excessive supplementation. Excessive sun exposure does not result in vitamin D toxicity, as the body shuts off the mechanism for converting UVB into vitamin D when the enzyme pathway is exhausted. Life guards have been shown to have levels of circulating 25(OH)2D3 above 100 nmol/l with no signs of toxicity1,6. However it has been recommended that levels remain between 50-75 ng/mol, which is best achieved through moderate amounts of sunlight, and a supplement of 1000 IU daily.
Further studies need to be done, on a larger scale monitoring not only cytokine levels, but MRI scans and patient reports of well being to fully establish a link between vitamin D supplementation and the inhibition of disease progression in individuals with MS. However, the preliminary reports look encouraging and it may provide relief for thousand of sufferers.
References:
1.Grant WB, Holick MF. Benefits and Requirements of Vitamin D for Optimal Health: A review. Alternative Medicine Review, (2005) 10(2), 94-111.
2.Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers and cardiovascular disease. Am J Clin Nutr (2004) 80(suppl): 1678S-1688S.
3.Moore C, Murphy MM, Keast DR, Holick MF. Vitamin D Intake in the United States. J American Dietetic Assoc. 2004.
4.Ponsonby AL, Lucas RM, Van der Mei IAF. UVR, vitamin D and three autoimmune diseases Multiple Sclerosis, Type 1 Diabetes, Rheumatoid Arthritis. Photochemistry and Photobiology, (2005) 81(6), 1267-1275.
5.Mahon BD, Gordon SA, Cruz J, Cosman F, Cantorna MT. Cytokine profile in patients with Multiple Sclerosis following vitamin D supplementation. J Neuroimmunology (2003) 134, 128-132.
6.Dawson-Hughes B, Heaney RP, Holick MF, Lips P, Meunier PJ, Vieth R. Estimates of optimal vitamin D status. Osteoporos Int, (2005),16, 713-716.
7.Hayes CE. Vitamin D: a natural inhibitor of multiple sclerosis. PNAS, (2000), 59, 531-535.
8.Cantorna MT, Mahon BD. Mounting evidence for vitamin D as an environmental factor affecting autoimmune disease prevalence. Exp Biol Med (2004) 229, 1136-1142.