Wednesday, 11 February 2015

Like buses. Vitamin D and autism again.

I don't know if everyone will have heard the term 'like buses' to infer that you seem to spend ages waiting for something (like a bus) and then two or more turn up at once. So it is with research, and the continuing interest that autism research seems to have with the sunshine vitamin/hormone that is vitamin D.

Following on from my recent discussions on the paper by Fernell and colleagues [1] (see here) talking about early low vitamin D potentially being 'connected' to cases of autism or autism spectrum disorder (ASD), so today I'd like to bring to your attention the findings reported by Bener and colleagues [2] (open-access here) who concluded: "Vitamin D deficiency was higher in autism children compared to healthy children and supplementing infants with Vitamin D might be a safe and more effective strategy for reducing the risk of autism." Just before anyone decides to pull me up on the use of the term 'healthy children' to denote asymptomatic controls (not-autism), those words belong the authors not me. Insofar as the notion that vitamin D supplementation might 'reduce the risk' of autism, I'd be minded to suggest that we need a little more experimental work in this area before anyone jumps the gun.

Some points from the recent paper:

  • Based in Qatar, a country probably not deficient in sunshine - one of the major environmental sources of vitamin D - the authors provide findings based on a case-control study detailing the biological levels of "serum 25-hydroxy Vitamin D, calcium, phosphorus and magnesium" alongside a few other variables. 
  • Analysis of their cohort of 254 children with autism and 254 controls revealed that: "Of [a] total 254 of autism children, 14.2% had severe Vitamin D deficiency (<10 ng/ml), 43.7% had moderate insufficient levels (between 10 and 20 ng/ml), 28.3% had mild insufficient levels (between 20 and 30 ng/ml), and only 13.8% of autism had sufficient levels (>30 ng/ml)." These figures whilst stark were not however altogether dissimilar from the control participants values (8.3% with deficiency, 37% moderate insufficient, 37% mild insufficient and 17% sufficient) bearing in mind the subtle shift towards a more severe deficiency present in the autism group (see a figure here). 
  • Totalling up the levels of vitamin D in their autism and control groups, the authors conclude: "there was statistically significant differences between autism and control subjects with respect to the serum level of Vitamin D (P = 0.023)." This was however also true across the other parameters included for study (see here). Indeed, differences in calcium levels topped the list of potential 'predictors' of an autism diagnosis (see here) something which I would have thought would have merited much more discussion from the authors.

As per the other research talking about vitamin D levels and autism (see here) including the idea that "lower serum 25(OH) D levels could be considered as an independent risk factor for ASD" [3] in some geographical/ethnic groups, it strikes me that there is quite a bit more investigation to do here. Bearing in mind that vitamin D deficiency/insufficiency is not just confined to autism (see here) and how one has to be a little cautious about single factors being universal triggers for a wide range of conditions, the very real effects of vitamin D deficiency even alongside a diagnosis of autism [4] imply that testing and a little clinical management for those that need it, should be rather more routine, save any further charges of health inequality for those on the autism spectrum.

Music... Come to Daddy by Aphex Twin (not for the faint-hearted).

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[1] Fernell E. et al. Autism spectrum disorder and low vitamin D at birth: a sibling control study. Molecular Autism. 2015; 6: 3.

[2] Bener A. et al. Is high prevalence of Vitamin D deficiency evidence for autism disorder?: In a highly endogamous population. J Pediatr Neurosci. 2014 Sep-Dec;9(3):227-33.

[3] Gong ZL. et al. Serum 25-hydroxyvitamin D levels in Chinese children with autism spectrum disorders. Neuroreport. 2014 Jan 8;25(1):23-7.

[4] Clark JH. et al. Symptomatic vitamin A and D deficiencies in an eight-year-old with autism. JPEN J Parenter Enteral Nutr. 1993 May-Jun;17(3):284-6.

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ResearchBlogging.org Bener, A., Khattab, A., & Al-Dabbagh, M. (2014). Is high prevalence of Vitamin D deficiency evidence for autism disorder?: In a highly endogamous population Journal of Pediatric Neurosciences, 9 (3) DOI: 10.4103/1817-1745.147574