Sunday, 16 February 2014

Does not support an association...

I want to briefly draw your attention to the paper by Fernando Navarro and colleagues* which concluded: "Our study although underpowered to show small differences does not support an association between dietary gluten/milk, IP [intestinal permeability], and behavioral changes in subjects with ASD". At the moment, I'm only blogging based on the study abstract so I'm gonna keep things quite brief and will post again when I have the full-text. BTW we had heard that this study was coming as far back as 2008 (see here for some media).

Anyone who knows me and my interest in all-things autism spectrum conditions would probably understand my degree of disappointment in the above statement from the study. Whilst having great faith in the principles of science and the scientific method, it's always a little bit difficult to digest results which cast doubt on something which you've put quite a few weeks/months/years examining (see here) particularly when published in the same journal that you have (see here and see here). But I do feel it's important to blog about the Navarro findings so as to remain impartial and objective and show that there are two sides to every science story.

The Novarro study, utilising the gold-standard randomised double-blind placebo controlled study design, looked at two elements which have cropped up with some frequency over the past few years when it comes to autism: (1) that removal of foods containing gluten and/or casein may impact on the presentation of some cases of autism (see here) and (2) leaky gut or rather intestinal hyperpermeability may be one reason why said dietary components seem to show some effect on cases of autism (see here).

Based on quite a short study duration (4 weeks) it appears that: "Neither the L/M ratio [lactoluse:mannitol ratio] nor behavioral scores were different between groups exposed to gluten/dairy or placebo. The changes observed were noted to be small and not clinically significant". I could start savaging the short study duration or what I think was the relatively small participant group included or the reliance on "the Aberrant Behavior Checklist and Conners Parent Rating [Scale]" but sour grapes don't make for good science. Indeed, I need to reiterate that this was a gold-standard trial in terms of methodology... This is also not the first time that the gluten- and casein-free (GFCF) diet for autism has fallen at the experimental stage as per the results reported by Elder and colleagues** under similar experimental conditions.

I'm not going to say much more than what I have already at this stage. I'm sure various opinions will be voiced about this study depending to some degree, on one's perspective on dietary intervention for autism and well, that's fair enough.

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* Navarro F. et al. Are ‘leaky gut’ and behavior associated with gluten and dairy containing diet in children with autism spectrum disorders? Nutr Neurosci [Advance Article] DOI: 10.1179/1476830514Y.0000000110

** Whiteley P. et al. The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutr Neurosci. 2010 Apr;13(2):87-100.

*** Pedersen L. et al. Data mining the ScanBrit study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders: Behavioural and psychometric measures of dietary response. Nutr Neurosci. 2013 Sep 7. [Epub ahead of print]

**** Elder JH. et al. The gluten-free, casein-free diet in autism: results of a preliminary double blind clinical trial. J Autism Dev Disord. 2006 Apr;36(3):413-20.

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ResearchBlogging.org Fernando Navarro, Deborah A Pearson, Nicole Fatheree, Rosleen Mansour, S Shahrukh Hashmi, & J Marc Rhoads (2014). Are ‘leaky gut’ and behavior associated with gluten and dairy containing diet in children with autism spectrum disorders? Nutritional Neuroscience DOI: 10.1179/1476830514Y.0000000110