Low Vitamin D Linked to Autism

SAN FRANCISCOLow vitamin D levels may be linked to increased autism risk, according to a new study conducted by the Vitamin D Council (Dermato-Endocrinology 2012; 4:4). The researchers hypothesized that low vitamin D levels have adverse effects on fetal brain development during pregnancy.

"These results add to the evidence that vitamin D deficiency may be an important risk factor for autism and suggest that pregnant women and autistic individuals raise their serum 25-hydroxyvitamin D concentrations above 30 ng/ml," the study authors wrote. One way mothers can increase their vitamin D levels is with supplementation.

In this study, researchers looked at U.S.  autism rates by state in white, black and Asian American children aged 6 to 17, and compared them to the amount of solar UVB light in their location. Vitamin D is synthesized in the body from UVB light.

They found states with higher UVB rays in summer or autumn had about half the rate of autism as sates with the lowest amounts. In states with the least solar UVB rays, black Americans had a 40-percent higher rate of autism than whites.

For white Americans, the regression coefficient for solar UVB doses and autism prevalence ranged from -0.52 in January to -0.57 in October. For black Americans, the regression coefficient for latitude was 0.61, whereas those for solar UVB ranged from -0.55 to -0.61. For Asian Americans, the values for solar UVB ranged from -0.28 to -0.38.

The analyses omit Alaska and Hawaii because of their extreme locations; Wyoming because they had no data, Arizona and North Dakota because of a low numbers of black Americans; and Washington D.C., Maine, Montana and South Dakota for low numbers of Asian Americans.  

A study from earlier this month found mothers who had higher levels of vitamin D had a better chance of giving birth to children with healthy birth weights. And a September 2012 study reported pregnant women who are deficient in vitamin D are more likely to give birth to children with slower brain development, and decreased mental and motor skills.