Gluten- and Casein-Free Diets for Autistic Spectrum Disorder

Millward C, Ferriter M, Calver S, Connell-Jones G

The Cochrane Library, Issue 2, 2004
Chichester, UK: John Wiley & Sons, Ltd.

Question: Is the gluten-free, casein-free diet effective in the treatment of symptoms in children with autism?

Data Sources: The authors searched the Cochrane Library, PsycINFO, EMBASE, CINAHL, MEDLINE, ERIC, LILACS, and the Cochrane Complementary Medicine Field register. The bibliographies of articles were also searched to find studies.

Participants: Children, teenagers, or adults who had received a formal diagnosis of autism using DSM-IV or ICD-10 criteria.

Study Selection: All randomized controlled trials that used casein-free, gluten-free, or casein- and gluten-free diets as the treatment were included. Only one randomized controlled trial was found in the literature search. It was subjected to the following criteria which are standard in the assessment of clinical trials: Was assignment to treatment really random? Was assignment to treatment or placebo/non-treatment concealed? Were all participants in the trial followed up and accounted for? Were dropouts followed up? How were the dropouts accounted for? Did those assessing the participants know which participants were in the active treatment group and which were not?

Outcome Measures: Urinary peptide concentrations, observations of behaviour and standardized behavioural assessments; communication and language skills, cognitive ability, and motor skills.

Data Extraction: Two of the review’s authors separately extracted the data from the trial.

Main Results: In the one reviewed study (Knivsberg 2002), children were placed on a combined gluten- and casein-free diet or on a “normal” diet. All the children had a formal diagnosis of autism and all had abnormal levels of urinary peptides at the start of the study. The level of urinary peptides was not measured at the end of the follow-up period. Testing showed no significant differences between the intervention and control groups in language, cognitive ability, or motor skills at follow-up. The diet group showed a greater reduction in autistic traits.

Conclusions: With the exception of the one study cited, none of the literature on the subject of the gluten-free, casein-free diet was conducted in a manner that could prove its effectiveness. The Knivsberg study did not show statistically significant differences in skills between the two groups. There was a reduction in autistic symptoms in the group that had the diet intervention. There was no information on the level of urinary peptides at follow-up. The study was small so the results must be met with caution. A larger trial is necessary to prove these findings.

Knivsberg A-M, Reichelt KL, Høien T, Nødland M. A randomised, controlled study of dietary intervention in autistic syndromes. Nutritional Neuroscience 2002; 5(4):251-261.