Could Autism Be Caused by Lack of Vitamin D?

Could autism be caused by low levels of vitamin D? That’s a new idea that’s just starting to emerge, sparked by the large number of autism cases among children of Somali immigrants living in Sweden and Minnesota.

The mothers and young children are exposed to much less sunshine in their new homes than they were back in Somalia. Lighter-skinned people make more vitamin D than dark-skinned people do when exposed to sunshine, so it’s easy to imagine that the Somalis are getting relatively little vitamin D. And because most of the Somali immigrants are Muslim, they cover themselves when going outside, reducing their sun exposure even more. But there’s as yet no clear connection to autism.

Gabrielle Glaser does a great job of exploring this big question in an article posted today at Scientific American online, explaining what scientists know about possible links between autism and vitamin D—and the many things that are still unclear. For instance, there’s no good data on the prevalence of autism in Somalia, so it’s impossible to nail down whether there really is an increase among the immigrant families.

Scientists are just starting to research whether vitamin D could play a role in autism. Their work includes testing pregnant women to find out what their blood levels of vitamin D are, something that’s not routinely done in prenatal office visits.

What’s a parent to do while this research is underway? Because many moms are D-deficient themselves, the American Academy of Pediatrics recently raised the daily vitamin D recommendation for babies and children from 200 IU to 400 IU. My colleague Dr. Bernadine Healy recently explained the debate over women and vitamin D; the consensus is leaning toward a recommended daily intake for adults of 800 to 1,000 IU of the D3 form of the vitamin, far more than the 400 IU in many daily vitamin supplements.