Vitamin D + Autism

And this from the Vitamin D Council...very interesting indeed!

The theory that vitamin D deficiency, during pregnancy or childhood, causes autism is just a theory. However, the theory has a plausible mechanism of action, explains all the unexplained facts about autism, subsumes several other theories, implies simple prevention, and is easily disprovable—all components of a useful theory. 

A genetic lesion (abnormality) in some component of the vitamin D system—a lesion vitamin D's unique pharmacology could overcome—would explain why monozygotic (identical) twins are highly affected while fraternal twins are not. Varying brain levels of activated vitamin D during later life would explain why some identical twins get severe disease while others are barely affected. 

Falling vitamin D levels over the last 20 years due to sun avoidance explain autism's rapid increase in incidence during that same time. The very different effects estrogen and testosterone have on vitamin D metabolism may explain why boys are much more likely to get it than girls are. Lower vitamin D levels in black individuals may explain their higher rates of autism. The vitamin D theory has tenable explanations for all the epidemiological features of autism.