According to a new study published in Neurology, African-Americans with multiple sclerosis (MS) may be more likely to have low vitamin d levels than African-Americans without MS.
Although researchers say part of the difference in vitamin D levels may be explained by variations in climate and geography, the findings support the growing link between vitamin D and multiple sclerosis risk.
African-Americans tend to have lower vitamin D levels than whites, possibly due to the higher levels of melanin in their skin. Melanin is a pigment in the skin that acts as a filter of ultraviolet (UV) light, which limits the amount of vitamin D that the body can produce in response to sunlight exposure.
Researchers say those who had MS were exposed to a lower monthly UV index (an average of 3.8 vs. 4.8) and lived an average of one degree of latitude farther north than those without the disease. They say the link between low vitamin D levels and MS was weaker but still significant after accounting for these differences.
The study also showed that people with a higher proportion of European ancestry in their genes were less likely to have low vitamin D levels.
Researcher Ari J. Green stated “These findings may provide a mechanism to help explain how genes and the environment interact to produce MS.”
Vitamin D is an essential nutrient derived from exposure to sunlight or through supplementation. People who have moderate to high dark skin color make much less vitamin D. Some studies suggest that almost 75 percent of African Americans are vitamin D insufficient.
Vitamin D deficiency is called a “hidden epidemic” for darker-skinned people who have more melanin in the skin. High levels of melanin reduce the body’s ability to make vitamin D from sunlight exposure.