Kocovská E, Fernell E, Billstedt E, Minnis H, Gillberg C. (2012) Res Dev Disabil. 33(5) 1541-50. doi: 10.1016/j.ridd.2012.02.015. Epub 2012 Apr 21.
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with multiple genetic and environmental risk factors. The interplay between genetic and environmental factors has become the subject of intensified research in the last several years. Vitamin D deficiency has recently been proposed as a possible environmental risk factor for ASD.
The aim of the current paper is to systematically review the research regarding the possible connection between ASD and vitamin D, and to provide a narrative review of the literature regarding the role of vitamin D in various biological processes in order to generate hypotheses for future research.
Systematic data obtained by different research groups provide some, albeit very limited, support for the possible role of vitamin D deficiency in the pathogenesis of ASD. There are two main areas of involvement of vitamin D in the human body that could potentially have direct impact on the development of ASD: (1) the brain (its homeostasis, immune system and neurodevelopment) and (2) gene regulation.
Vitamin D deficiency - either during pregnancy or early childhood - may be an environmental trigger for ASD in individuals genetically predisposed for the broad phenotype of autism. On the basis of the results of the present review, we argue for the recognition of this possibly important role of vitamin D in ASD, and for urgent research in the field.
The idea that Vitamin D deficiency might play a role in autism was first put forward by John Cannell of the Vitamin D Council, who has published two reviews on this subject:
In 2009, Scientific American's gave coverage of this theory in a review article: What If Vitamin D Deficiency is a Cause of Autism?
Since then, some further evidence for an association between low Vitamin D and autism risk has been forthcoming, as this review concludes.
Definitive evidence (in the form of Randomised Controlled Trials) is likely to remain extremely hard to come by, given the developmental nature of autism, and the relatively long time scale between any deficiencies in early life (when the effects are likely to be most pronounced) and the emergence of autistic behaviours. Further research is urgently required, as this review concludes.
Meanwhile, however, Vitamin D deficiency is now so widepread - and has implications for so many other aspects of physical and mental health - that there is already a strong case for addressing this in any case as a major public health issue.
See also: Vitamin D and Autism for a fuller list of FAB references and resources on this subject.