Preventing Chronic Disease: July 2010: 10_0066 / The Prevalence of Multiple Sclerosis in 3 US Communities: The Role of Vitamin D

LETTER
The Prevalence of Multiple Sclerosis in 3 US Communities: The Role of Vitamin D

Suggested citation for this article: Grant WB. The prevalence of multiple sclerosis in 3 US communities: the role of vitamin D [letter]. Prev Chronic Dis 2010;7(4). http://www.cdc.gov/pcd/issues/2010/jul/10_0066.htm. Accessed [date].

To the Editor:
Authors of the recent article on the prevalence of multiple sclerosis (MS) in 3 US communities (1) presented excellent findings but stumbled on their interpretation. The article noted that the findings were similar to those in a study of MS prevalence from the 1940s and 1950s (2); however, the authors did not make a detailed comparison with those data. Furthermore, the authors noted that UV radiation could explain the findings but did not suggest a mechanism for the link.

The data in reference 2 have been analyzed in previous studies, which found the distribution of MS in the United States to be well described by a quadratic fit to latitude (3). This fit is related to wintertime solar UVB (4). Winter is the season with the lowest levels of serum 25-hydroxyvitamin D in humans and the highest rate of viral infections (4). In a comparison of the prevalence data from reference 1 with those from reference 2, the recent data indicate a prevalence of approximately 7 cases per 100,000 per year less but with the same functional fit (Figure). The quadratic fit to the data in reference 2 explains 75% of the variance.

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Preventing Chronic Disease: July 2010: 10_0066