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Dietary restrictions may do more harm than good for children with autism
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New data do not support the relationship between autism and gastrointestinal dysfunction that some have hypothesized.
Researchers at the Mayo Clinic in Rochester, Minn., were the first to compare the incidence of GI symptoms among children with autism to those without to explore the popular, yet scientifically-limited belief that toxins produced by GI diseases are involved with the neurodevelopmental symptoms of autism.
Many parents who believe this theory have adopted interventions including restrictive diets; vitamin, mineral and other dietary supplements as well as the use of various antifungal medications.
Data from the retrospective study that spanned between 1976 and 1997 indicated that there were no significant differences in overall GI symptom prevalence as defined by three of five diagnostic categories — including diarrhea; abdominal bloating, discomfort or irritability; and gastroesophageal reflux or vomiting — between a matched control group and 121 patients aged younger than 21. These patients lived in Olmstead County, Minn., and met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for autism.
Although children with autism did experience a higher cumulative incidence of constipation (33.9% vs. 17.6%) and feeding issues/food selectivity (24.5% vs. 16.1%) compared with the case-control group, the researchers suggested that these symptoms may be the result of behavioral characteristics common to the disorder.
“The ritualistic tendencies, need for routine and insistence on sameness that are characteristic of children with autism may lead these children to choose and demand stereotyped diets that may result in an inadequate intake of fiber, fluids and other food constituents,” they wrote.
Furthermore, both increases in appetite and appetite suppression are known side effects associated with psychotropic and stimulant medications commonly prescribed to treat these symptoms.
The researchers suggested that dietary interventions coupled with existing food selectivity issues may increase the risk for nutritional deficiencies.
“The findings from our study suggest that such treatments should not be provided indiscriminately to children with autism unless there is explicit evidence indicating the presence of a GI disorder in a specific case,” they wrote. – by Nicole Blazek
Ibrahim SH. Pediatrics. 2009;124:680-686.
Although the notion that there is an important association between gastrointestinal problems and autism is popular, the relationship is actually unclear. Some studies have found that GI problems are equally common in children with autism and controls, and others have suggested that they are substantially more common in the group with autism. However, most were not population-based studies involving representative groups of children with autism and appropriate controls, and many ascertained the presence of GI problems only by parent report.
This study showed that there was no difference in the cumulative incidence of gastrointestinal problems between a well-characterized population cohort of 121 individuals with autism and 242 matched controls. Information about GI diagnoses and symptoms was obtained from complete medical records rather than being based on parent report, which helps to avoid recall bias. It would be useful to know whether there was a difference in severity, duration or recurrence rate of GI problems between the groups. The authors indicate that the next phase of this project will include assessment of these factors.
It would also be interesting to know whether there was an association between GI problems, history of language regression and family history of autoimmune diseases in this cohort, since such an association has been reported recently.
Two subgroups of GI problems — constipation and feeding issues/food selectivity — were significantly more common in the autism group. Some of us have observed anecdotally that although constipation is common in our patients with autism, it seems to be equally common in our patients with other developmental disabilities such as intellectual disability and ADHD. I suspect that this hypothesis could be tested retrospectively using data from the Rochester Epidemiology Project.
This does not mean that GI problems are not important when they do occur in children with autism or other developmental disabilities. In a carefully-studied convenience sample of 172 children with autism who participated in two Research Units on Pediatric Psychopharmacology Autism Network trials, those with significant GI problems (22%, mostly constipation) had greater symptom severity on measures of irritability, anxiety and social withdrawal relative to those without GI problems, and were more refractory to treatment with risperidone (Risperdal, Janssen) .
Further research is needed to examine the association between GI problems and specific characteristics of children with autism and other developmental disabilities and to clarify the behavioral impact of identifying and treating GI problems.
Sometimes when possible associations are noted anecdotally and theories are popularized, undue significance is attributed to common problems. Often, the claim that GI problems are rampant in children with autism is used to justify various unproven treatments.
Based on the currently available information, it is fallacious to argue that the epidemiology of GI problems supports the use of elimination diets, digestive enzymes, antifungal medications, oral immunoglobulin, antibiotics or dietary supplements in children with autism.
– Scott M. Myers, MD
Infectious Diseases in Children Editorial Board