Gluten-Free Diet in Children with Autism Spectrum Disorders: A Randomized, Controlled, Single-Blinded Trial
Authors:
Piwowarczyk, A., Horvath, A., Pisula, E., Kawa, R. and Szajewska, H
This study investigated the effects of a gluten-free diet (GFD) versus a gluten-containing diet (GD) on children with autism spectrum disorders (ASD). The study included 66 children aged 36 to 69 months who had been on a GFD for at least 8 weeks prior to enrollment. After an 8-week run-in period on a GFD, participants were randomly assigned to either continue the GFD or switch to a GD (consuming at least one gluten-containing meal per day) for 6 months. Below is a summary of the findings regarding autism symptoms and gastrointestinal (GI) symptoms.
Autism Symptoms
Assessment Tools:
The primary outcome, autism symptoms, was measured using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), which assesses core symptoms such as social affect (SA) and restricted and repetitive behaviors (RRB).
Secondary outcomes included parent-reported symptoms using the Social Communication Questionnaire (SCQ) and the Autism Spectrum Rating Scale (ASRS), as well as maladaptive behaviors assessed with the Vineland Adaptive Behavior Scale, Second Edition (VABS-2). Intellectual abilities were evaluated with the Leiter International Performance Scale.
Findings:
No Between-Group Differences: After 6 months, there were no significant differences between the GFD and GD groups in autism symptoms (ADOS-2 scores), maladaptive behaviors (VABS-2), or intellectual abilities (Leiter IQ scores). This indicates that reintroducing gluten did not worsen autism-related symptoms compared to maintaining a GFD.
Within-Group Improvements: Both groups showed some improvements over time in specific areas:
ADOS-2 RRB domain scores decreased (p = 0.023), suggesting a reduction in restricted and repetitive behaviors.
SCQ scores improved (p = 0.016), indicating better parent-reported social communication.
ASRS total scores decreased (p = 0.024), reflecting a reduction in parent-reported autism symptoms.
Interpretation: These improvements were observed in both the GFD and GD groups, suggesting they were not specifically attributable to the dietary intervention but rather to other factors, such as time or ongoing development.
Gastrointestinal Symptoms
Assessment Tool: GI symptoms were evaluated using the ROME III questionnaire (Parent Report Version), which identifies functional GI disorders such as abdominal pain and constipation.
Findings:
Reported Symptoms: Only abdominal pain and constipation were reported by participants, with a frequency of 34% across the study population, which is lower than some previous reports of GI symptoms in children with ASD (37.4% to 49%).
No Between-Group Differences: At baseline and after 6 months, there were no significant differences in the prevalence of abdominal pain or constipation between the GFD and GD groups:
Baseline: Abdominal pain (9% in both groups, p = 0.99); Constipation (24% GD vs. 27% GFD, p = 0.78).
6-Month Follow-Up: Abdominal pain (3% GD vs. 7% GFD, p = 0.6); Constipation (31% GD vs. 26% GFD, p = 0.45).
Interpretation: The lack of differences suggests that reintroducing gluten did not increase GI symptoms compared to maintaining a GFD over the 6-month period.
Additional Observations
Study Design: The trial was single-blinded (researchers blinded, parents aware of group assignment), included a run-in period to standardize baseline GFD exposure, and used standardized, validated tools. The sample was homogenous for intellectual ability (IQ > 70), reducing confounding factors.
Limitations: The prior GFD exposure of all participants and the single-blinded design (potential for parental bias) are noted limitations. The 6-month duration may also be insufficient to detect long-term effects.
Conclusion: The study found no evidence that a GFD, compared to a GD, affects autism symptoms or GI symptoms in children with ASD over 6 months. The authors suggest that longer-term studies are needed to explore potential delayed effects of gluten exposure.
In summary, this trial indicates that reintroducing gluten into the diets of children with ASD who were previously on a GFD does not significantly impact their autism symptoms or GI functioning within a 6-month timeframe, challenging the hypothesis that gluten avoidance universally benefits this population.
https://pubmed.ncbi.nlm.nih.gov/31659595/
doi: 10.1007/s10803-019-04266-9