Autism and Gastrointestinal Issues: Assessment and Support in Ontario

Holingue et al. (2018) conducted a meta-analysis of 15 studies and found GI symptom prevalence of 46-84% in autistic children compared to 5-31% in non-autistic children. Constipation is the most commonly reported GI condition, affecting approximately 22% of autistic children. Chronic diarrhea, functional abdominal pain, and gastroesophageal reflux are also significantly elevated.

The reasons for elevated GI rates in autism are not fully understood. Contributing factors include autonomic nervous system differences affecting gut motility, restricted dietary patterns limiting fiber and fluid intake, sensory-based food selectivity reducing diet variety, medication side effects (particularly from atypical antipsychotics and SSRIs), and anxiety-related gut-brain axis activation. The microbiome composition of autistic individuals also differs from neurotypical peers, though the clinical significance of this finding is still under investigation.

GI symptoms in autistic children may present atypically. A child who cannot verbalize abdominal pain may express it through increased aggression, self-injurious behavior, sleep disruption, food refusal, unusual posturing, or pressing their abdomen against furniture. Any unexplained behavioral change in an autistic child should prompt GI evaluation.

Food selectivity affects approximately 70% of autistic children, compared to 13-22% of neurotypical children. Selectivity is driven by sensory factors (texture, temperature, color, smell, appearance), need for sameness, interoceptive differences affecting hunger/fullness signals, and oral motor sensitivities. This is not "picky eating" — it represents genuine sensory and neurological differences that make certain foods intolerable.

Nutritional consequences of food selectivity can include deficiencies in fiber, calcium, iron, vitamins A and C, and omega-3 fatty acids. A registered dietitian with autism experience should assess nutritional status and develop a plan that respects sensory needs while expanding dietary variety where possible. Ontario dietitians specializing in pediatric autism nutrition can be accessed through hospital programs (SickKids, CHEO) or privately ($120-$180 per session).

Pediatric gastroenterology in Ontario is accessed through physician referral. Key centres include SickKids, CHEO, McMaster Children's Hospital, London Health Sciences Centre, and Kingston Health Sciences Centre. Waits vary by centre and urgency.

Primary care providers can initiate basic GI evaluation (bloodwork, stool studies, dietary assessment) while awaiting specialist consultation. The consensus statement from Buie et al. (2010) recommends that autistic children presenting with behavioral changes should receive thorough GI evaluation, as GI pain is a leading cause of unexplained behavioral changes.

Feeding therapy may be provided by occupational therapists or speech-language pathologists with pediatric feeding training. Ask about approach, OAP eligibility, private fees, and expected timeline.