The prevalence of autism varies by geographic area. A new analysis indicates that autism is half as common in areas where there is more sunshine in the summer and fall. In states with the least sunshine, African Americans had a rate of autism 40 percent higher than that of white Americans. The dark pigment in skin reduces the amount of vitamin D the skin manufactures, especially when sunlight is more limited.
The authors speculate that vitamin D deficiency or insufficiency during pregnancy would affect brain development in the fetus. They point to another recent study showing that autistic children with the least vitamin D in their bodies have more severe symptoms. They recommend that pregnant women take vitamin D supplements to achieve optimal blood levels of 25-hydroxy-vitamin D and that autistic children be tested for vitamin D deficiency.
[Dermato-Endocrinology, online Dec 13, 2012]
The People's Perspective on Medicine