Table 5.

An overview of gastrointestinal (GI) symptoms reported in individuals with ASD.

Source	Sample size	Prevalence	GI symptoms
McElhanon et al. (125)	N = 15 studies	Higher rates of diarrhea (OR, 3.63), constipation (OR, 3.96), abdominal pain (OR, 2.45).	Diarrhea, constipation, abdomen pain
Mazurek et al. (128)	N = 2,973 ASD	24% had at least one type of chronic GI problem.	Constipation, abdominal pain, bloating, diarrhea and/or nausea lasting 3 months or more. Sensory over-responsivity and anxiety were highly associated with GI symptoms.
Mazefsky et al. (129)	N = 95 ASD	61% reported at least one GI symptom.	Abdominal pain, not hungry, bloating. Participants with GI problems also had significantly higher levels of affective problems.
Chandler et al. (130)	N = 132 ASD, N = 81 other developmental conditions, N = 82 Controls	46.5% ASD had at least one individual GI symptom, relative to 29.2% other developmental conditions and 21.8% in Controls.	Vomiting, diarrhea, abdominal pain, constipation. No association between GI symptoms and ASD severity.
Prosperi et al. (131)	N = 163 ASD	25.8% had at least one severe GI symptom.	Constipated (22.1%), Painful bowel movement (7.4%).