|You might feel a sharp scratch...|
It's not new news that functional bowel disorders such as constipation and diarrhoea tend to be quite frequent issues accompanying quite a few cases of autism. I've covered some of the research on this topic before on this blog (see here). I might in particular, draw your attention to the meta-analysis by Barbara McElhanon and colleagues  (open-access) that concluded: "Children with ASD [autism spectrum disorder] experience significantly more general GI symptoms than comparison groups".
Although there is now pretty widespread acceptance that bowel issues can and often do accompany autism, there is still a degree of reticence to talk about what might be causing such issues and what *might* be done about them , specifically when approached in the context of more serious underlying bowel disorders potentially being linked to said functional bowel issues (see here). I hark back to one of my first ramblings on this topic which was titled: 'Should I mention gastrointestinal symptoms in autism?' as an example of how delicate an area of investigation this was/is.
I'd like to think that the paper from Ridha et al might however continue to open this research area up and highlight how the so-called gut-brain axis is growing in both acceptance and understanding. The additionally interesting data from the authors suggesting that: "15.8 % of patients with constipation were obese, compared to 6.4 % in the general Australian paediatric population" whilst not necessarily autism-exclusive might also stimulate further interest in light of the analysis of weight and activity with autism in mind too (see here). Oh, and that nutritional deficiency and a higher body mass index (BMI) might also be another curious combination for some on the autism spectrum .
I'm going to chance my [speculating] luck and say that among the many factors potentially involved in these combined factors, a role for those trillions of wee beasties that call us home (the gut microbiome) might also show some involvement...
Music: Joe Cocker - With A Little Help From My Friends (RIP).
 Ridha Z. et al. Predictors of slow colonic transit in children. Pediatr Surg Int. 2014 Dec 31.
 Croaker D. et al. PO-0110 Predictors Of Slow Colonic Transit In Children. Arch Dis Child 2014; 99: A285.
 McElhanon BO. et al. Gastrointestinal symptoms in autism spectrum disorder: a meta-analysis. Pediatrics. 2014 May;133(5):872-83.
 Coccolrullo P. et al. Lactobacillus reuteri (DSM 17938) in Infants with Functional Chronic Constipation: A Double-Blind, Randomized, Placebo-Controlled Study. J Peds. 2010; 157: 598-602.
 Shmaya Y. et al. Nutritional deficiencies and overweight prevalence among children with autism spectrum disorder. Res Dev Disabil. 2014 Dec 19;38C:1-6.
Ridha Z, Quinn R, & Croaker GD (2014). Predictors of slow colonic transit in children. Pediatric surgery international PMID: 25549892