Table 1.
The characteristics of the included studies in the meta-analysis.
| References | Region, | Sample size | Sample size | Male | Mean age (years), | Mean age (years), | Intervention | Control | Duration |
|---|---|---|---|---|---|---|---|---|---|
| Country | intervention group | control group | (%) | intervention group | control group | ||||
| Smith et al. (13) | USA | 7 | 7 | 80.0 | 7.32 | 7.32 | GFCF | Regular diet | 6 weeks |
| Elder et al. (17) | Egypt | 25 | 15 | 73.3 | 5.29 | 5.29 | MAD, GFCF | Balanced nutrition | 6 months |
| Karhu et al. (14) | Iran | 38 | 38 | 73.6 | 7.84 | 8.00 | GFD | Regular diet | 6 weeks |
| Page et al. (28) | Spain | 15 | 16 | 54.1 | 8.80 | 9.10 | GFCF | Regular diet | 6 months |
| Ghalichi et al. (18) | Norway | 10 | 10 | NA | 7.60 | 7.20 | GFCF | Regular diet | 12 months |
| Piwowarczyk et al. (19) | China | 50 | 50 | 77.0 | 3.59 | 3.61 | KD | Regular diet | 10 weeks |
| Baspinar et al. (15) | Poland | 26 | 31 | 84.8 | 3.75 | 3.83 | GFD | GD | 6 months |
| References | Study Design | Inclusion Criteria | Exclusion Criteria | Main assessment Tools | |||||
| Smith et al. (13) | Double-blinded, crossover RCT | Diagnosis of ASD according to DSM-4 | Patients with medical histories and/or physical examinations indicated that they had physical or sensory impairments or significant medical problems, including celiac disease | CARS score | |||||
| Elder et al. (17) | RCT | Diagnosis of ASD according to DSM-5 | Patients with fat metabolism disorders, dyslipidemia, pyruvate carboxylase deficiency, porphyria, presence of kidney stones, liver disease, feeding problems or failure to thrive, gastroesophageal reflux, poor oral intake, cardiomyopathy, or chronic metabolic acidosis | CARS score | |||||
| Karhu et al. (14) | RCT | Diagnosis of ASD according to ADI-R by a psychologist |
Patients not diagnosed as ASD according to ADI-R by a psychologist, feeding difficulties based on parent report, or inpatients and children with additional illnesses or abnormalities | CARS-2 score | |||||
| Page et al. (28) | Crossover RCT | Diagnosis of ASD according to ICD-10 | Patients diagnosed with an allergy to gluten or casein; patients who had previously excluded gluten and/or casein from their diet; patients who were likely to not adhere to the diet properly | ATEC scale | |||||
| Ghalichi et al. (18) | RCT | Diagnosis of both ASD and abnormal urinary peptide patterns | NA | DIPAB autistic traits | |||||
| Piwowarczyk et al. (19) | RCT | Diagnosis of ASD according to DSM-5 | Patients with nutritional and metabolic diseases, abnormal growth and development, or other significant medical problems. | ABC score | |||||
| Baspinar et al. (15) | Single-Blinded, RCT | Diagnosis of ASD according to DSM-5 or ICD-10 | Patients with celiac disease, wheat allergy, inability to Cooperate, malnutrition, or presence of disease(s) influencing behavior, feeding, or growth | ADOS-2 | |||||
GFCF, gluten-free and casein-free diet; MAD, modified ketogenic diet; KD, ketogenic diet; GFD, gluten-free diet; GD, gluten-containing diet. ASD, Autism spectrum disorder; DSM-4/5, the Diagnostic and Statistical Manual of Mental Disorders, Fourth/Fifth Edition; ADI-R, Autism diagnostic interview-Revised; ICD-10, the tenth edition of the International Classification of Diseases; GARS, Gilliam Autism Rating Scale; ATEC, Autism Treatment Evaluation Checklist; DIPAB, a standardized Danish scheme to evaluation behavior; ABC, Autism children behavior checklist; ADOS-2, Autism Diagnostic Observation Schedule, Second Edition; NA, not available.