Full-text evidence summary

Multiple sclerosisExposure to sunlight

MS incidence, white male veterans, place of residence prior to enlistment. Case-control ratios x100.

Vitamin D may reduce the risk of developing MS.  The geographical variation of MS prevalence in Europe, North America and Australia1 2 3 is consistent with this suggestion.

The prevalence of MS increases with latitude (with the exception of the Nordic countries, where prevalence rates are slightly lower than countries immediately to the south).

This latitudinal dependence has been ascribed to wintertime solar ultraviolet B (UVB) doses in general, and additional oral intake of vitamin D in the Nordic countries4 5.  There is no evidence of any long-term shift in the geographical variation of the prevalence of MS in the United States6 7; however, there may have been some shift in the 1970s-1990s due to people moving from the “Rust Belt” to the “Sun Belt”, taking disease developed at higher latitudes to lower latitudes.

Page last edited: 03 May 2011


  1. Kurtzke, J. F. Epidemiologic evidence for multiple sclerosis as an infection. Clin Microbiol Rev. 1993 Oct; 6 (4): 382-427.
  2. Taylor, B. V. Lucas, R. M. Dear, K. Kilpatrick, T. J. Pender, M. P. van der Mei, I. A. Chapman, C. Coulthard, A. Dwyer, T. McMichael, A. J. Valery, P. C. Williams, D. Ponsonby, A. L. Latitudinal variation in incidence and type of first central nervous system demyelinating events. Mult Scler. 2010 Apr; 16 (4): 398-405.
  3. Wallin, M. T. Page, W. F. Kurtzke, J. F. Multiple sclerosis in US veterans of the Vietnam era and later military service: race, sex, and geography. Ann Neurol. 2004 Jan; 55 (1): 65-71.
  4. Grant, W. B. Garland, C. F. Holick, M. F. Comparisons of estimated economic burdens due to insufficient solar ultraviolet irradiance and vitamin D and excess solar UV irradiance for the United States. Photochem Photobiol. 2005 Nov-Dec; 81 (6): 1276-86.
  5. Grant, W. B. Holick, M. F. Benefits and requirements of vitamin D for optimal health: a review. Altern Med Rev. 2005 Jun; 10 (2): 94-111.
  6. Grant, W. B. Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers. Photochem Photobiol. 2008 Mar-Apr; 84 (2): 356-65.
  7. Grant, W. B. The prevalence of multiple sclerosis in 3 US communities: the role of vitamin D. Prev Chronic Dis. 2010 Jul; 7 (4): A89; author reply A90.