Can urinary indolylacroylglycine (IAG) levels be used to determine whether children with autism will benefit from dietary intervention? : Autism, gastrointestinal problems and IAG

BACKGROUND: An increase in urinary indolyl-3-acryloylglycine (IAG) has been reported in children with ASD who suffer with bowel problems in comparison to ASD children without gastrointestinal (GI) problems. The case for dietary intervention for ASD children with GI symptoms might be strengthened were such a difference to be autism-specific. METHODS: Quantitative analysis of urinary IAG levels was performed for 53 children on the autism spectrum and 146 age-matched controls. The parents of each child were asked to provide information on bowel symptoms experienced by the child and their eating habits over a period of two weeks. RESULTS: We find no significant difference in urinary IAG levels between the ASD children with GI problems and ASD children without GI problems. Although we see some difference between ASD children with GI problems and controls in mainstream schools with GI problems, the difference between non-autistic children with other developmental disorders and controls in mainstream schools is more significant so that any difference is not autism-specific. We find a strong correlation between bowel symptoms and diet problems in ASD children, especially idiosyncratic feeding behavior and we show that ASD children suffering from multiple bowel symptoms tend to be those who also have dietary problems. CONCLUSION: We found no evidence to support the hypothesis that children with ASD who suffer with bowel problems have increased levels of urinary indolyl-3-acryloylglycine in comparison to children with ASD who do not have gastrointestinal problems.