It is too early to say vitamin D has a treatment effect in autism. However, a simple risk/benefit analysis suggests that autistic children should be diagnosed and aggressively treated for vitamin D deficiency. If readers want to learn more about vitamin D and autism, they can obtain the entire paper on the link below. Unfortunately, Elsevier charges $31.50 to download it. You can read a similar document for free on the website, where we first published the theory a year ago.
Cannell JJ. Autism and vitamin D. Med Hypotheses. 2008;70(4):750-9.
Vitamin D Newsletter May 2007 | Vitamin D and Autism
In summation, autistic children should be given enough vitamin D to get their 25(OH)D levels up to the mid to high range of normals, that is, 70 ng/ml (175 nmol/L in countries that use the metric system). In the absence of sun exposure, this usually requires long-term administration of about 1,000 IU/day per 20 pounds of body weight with a loading dose of 2,000 IU of vitamin D/day for every 20 pounds of body weight for the first two weeks. As individual variation in response is very high, they should have 25(OH)D blood tests every month until their level has stabilized around 70 ng/ml. They should stop all products containing preformed retinols (vitamin A), especially cod liver oil.
John Cannell, MD
The Vitamin D Council