AutismVitamin D levels

Cannell pointed out that children with Williams syndrome1, who have greatly elevated 1,25-dihydroxyvitamin D levels in early infancy2 often have characteristics opposite to those of autism: remarkable sociability, overfriendliness, empathy, and willingness to initiate social interaction3

Additional evidence for a role of vitamin D in explaining the prevalence and symptoms of autism have appeared since Cannell’s hypothesis was first proposed4. For example, subsequent studies provided more evidence that dark skin is a risk factor for development of autism5 6.

A recent paper examined the presence of autism according to maternal immigrant status and ethnic origin7. Four papers8 9 10 11 regarding maternal foreign birth and three papers regarding maternal ethnic origin8 12 13 were reviewed. All four foreign birth studies found significantly increased risk of autism for some of the countries. Most of the maternal ethnic origin studies found significantly increased risk of autism for black vs. white mothers. Two studies did not find significant risk of autism related to paternal immigrant status10 or ethnic origin13. It was also noted that the association between autism and maternal 25(OH)D levels is similar to that for schizophrenia14 15. This review provides strong support for the UVB-vitamin D-autism hypothesis. 

Two papers reported differences in bone development for those with autism: one regarding metacarpal bone thickness16, the other involving second and fourth finger digit lengths17. Since a primary role of vitamin D is control of calcium absorption and metabolism, these two studies provide indirect evidence for a role of vitamin D deficiency in the etiology of autism.

“Compared with infants born at term, the unadjusted ORs for autistic disorders among very and moderately preterm infants were 2.05 [95% CI: 1.26-3.34] and 1.55 [95% CI: 1.22-1.96], respectively.”18. Low maternal serum 25(OH)D levels are a risk factor for premature delivery19. However, there are other risk factors for preterm delivery.

Preeclampsia has also been found associated with increased risk of autism20. Low maternal 25(OH)D level is a risk factor for preeclampsia21.

Maternal seafood consumption during pregnancy is associated with reduced risk of the child developing autism22. Cold water ocean fish are a good source of vitamin D23.

While these and other findings do not prove that vitamin D reduces the risk of autism, the theory is strong enough that it “deserves immediate attempts to disprove it”24.

Page last edited: 17 May 2011


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