Vitamin D helps regulate the immune system and maintain bone density. As people with MS have an excessively active immune system and are at increased risk of developing osteoporosis, vitamin D has therapeutic potential.

Vitamin D is both a vitamin and a hormone. Formation of vitamin D is dependent on sun exposure; thus, inadequate sunlight may produce a vitamin D deficiency. Generally, ten to fifteen minutes of casual exposure to the sun is adequate for normal vitamin D production.

Calcium and vitamin D have been shown to work together to produce strong bones. Therefore, vitamin D may help prevent the development of osteoporosis. People with MS are at an increased risk of developing osteoporosis for many reasons: they are usually less active, are more likely to be female than male, usually have less sun exposure, may be taking steroids for treatment, and often have a vitamin D deficiency. People with MS are two to three times more likely to fracture bones than healthy individuals.

Vitamin D may also play an important role in regulating the immune system by suppressing its activity. Vitamin D supplements have been shown to slow the progression of EAE, an animal model of MS.

Large epidemiologic studies have found that sun exposure and vitamin D supplementation are associated with lower risk of developing MS or dying from the disease. Similar trends exist for diabetes and lupus, other immune conditions.

Limited clinical research has been conducted evaluating the effectiveness of vitamin D in MS. One small study, which lacked a placebo group, suggested vitamin D decreases the frequency of MS attacks. Due to the limitations of this study and the fact that it also involved the use of omega-three fatty acids, the results are difficult to interpret (see Diets and Fatty-Acid Supplements page). Another study found that 6 months of 19-nor-vitamin D supplements (a form of vitamin D) treatment did not produce significant clinical benefits nor did it decrease the severity of the disease as measured by MRI. Calcitriol, the active form of vitamin D, was found in one study to be safe and well tolerated by individuals with MS for up to 12 months. Large scale clinical trials are needed to further characterize the safety and effectiveness of vitamin D.

Geographical research has further indicated that vitamin D may play a role in MS. The prevalence of MS is known to increase with distance from the equator. Sunlight exposure decreases with distance from the equator, and as sunlight is necessary for vitamin D production, average levels of vitamin D decrease as well. Therefore the closer to the poles an individual lives, the more likely he or she will develop MS and also have a vitamin D deficiency. In Switzerland, MS was found to be more common at low altitudes. It has been suggested that this is due to the fact that more ultraviolet light is present at higher levels at higher altitude, thus increasing vitamin D levels and possibly preventing MS. Stuides in Norway showed that MS was more common in those who lived in the coastal areas than in those who lived inland. As coastal people eat more fish, which is high in vitamin D, it has been suggested that dietary intake of vitamin D may prevent MS in these people. However, as fish also contain a large amount of omega-three fatty acids, the effects of vitamin D alone are not clear (see Diets and Fatty Acid Supplements page).

Tests may be done to determine blood levels of vitamin D and bone density. If vitamin D supplementation is indicated by these tests, it is often recommended that calcium supplements be taken as well. Dosing should be discussed with a health professional, but the normal adequate intake of vitamin D is 200 to 600IU daily. It is possible that prescription medications may also be necessary, or, in the case of postmenopausal women, hormone replacement therapy. If vitamin D is taken in high doses it may cause abdominal cramps, fatigue, kidney damage, nausea, vomiting, hypertension, and various other adverse reactions. Calcium and iron may affect each other’s absorption and therefore should not be taken together.

References and Additional Reading


Bowling AC. Complementary and Alternative Medicine and Multiple Sclerosis. New York: Demos Medical Publishing, 2007.

Bowling AC, Stewart TS. Dietary Supplements and Multiple Sclerosis: A Health Professional’s Guide. New York: Demos Medical Publishing, 2004.

Jellin JM, Batz F, Hitchens K, et al. Natural Medicines Comprehensive Database. Stockton, CA: Therapeutic Research Faculty, 2009.

Ulbricht CE, Basch EM, eds. Natural Standard Herb and Supplement Reference: Evidence-Based Clinical Reviews. St. Louis: Elsevier-Mosby, 2005.

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