Food and Behaviour Research

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Autism prevalence in the United States with respect to solar UV-B doses: An ecological study.

Grant WB, Cannell JJ. (2013) Dermatoendocrinol. 2013 Jan 1; 5(1) 159-64. doi: 10.4161/derm.22942. 

Web URL: View this and related abstracts via PubMed here. Free full text of this article is available online


Evidence is mounting that vitamin D deficiency is intimately involved in autism. We report on autism prevalence by US state for those aged 6-17 y in 2010 with respect to indices of solar UV-B (UVB) doses.

We calculated autism prevalence rates for white, black and Asian Americans by using total prevalence and relative populations of minors for each ethnic group by state. Analyses omit AK and HI (considered extreme cases), WY (no data), along with AZ and ND for black Americans (low numbers) and DC, ME, MT, ND and SD for Asian Americans (low numbers).

For white Americans, the regression coefficient for solar UVB doses and autism prevalence ranged from -0.52 in January to -0.57 in October. For black Americans, the regression coefficient for latitude was 0.61, whereas those for solar UVB ranged from -0.55 to -0.61. For Asian Americans, the values for solar UVB ranged from -0.28 to -0.38.

The inverse correlation between solar UVB and autism prevalence is similar to that for many types of cancer in the US. The journal literature indicates that adverse effects on fetal brain development during pregnancy due to vitamin D deficiency can explain these findings. However, we cannot rule out a role of vitamin D deficiency in early life.

These results add to the evidence that vitamin D deficiency may be an important risk factor for autism and suggest that pregnant women and autistic individuals raise their serum 25-hydroxyvitamin D concentrations above 30 ng/ml.


25(OH)D; African American; Asian American; autism; ecological; pregnancy; serum 25-hydroxyvitamin D; ultraviolet-B; vitamin D


Most Vitamin D is produced from the action of bright sunlight on the skin rather than from dietary sources. Deficiencies are now widespread in almost all developed countries owing to a combination of indoor lifestyles and public health campaigns emphasising only the potential risks of excessive UV exposure.

For some years, evidence has been mounting that a lack of Vitamin D in early life can have lifelong effects on brain development and functioning that may raise the risks of neurodevelopmental conditions such as schizophrenia, ADHD and autism, as well as many physical health conditions.

Findings from this study are consistent with other evidence for a link between Vitamin D deficiency and autism, although the data are correlational, so cannot address the key issue of causality.

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