Matthews, J. S., & Adams, J. B. (2023). Ratings of the effectiveness of 13 therapeutic diets for autism spectrum disorder: Results of a national survey. Journal of Personalized Medicine, 13(10), 1448.

Reviewed by:
Kate McKenna, MEd, MSEd, MS, BCBA, Association for Science in Autism Treatment
Videsha Marya, PhD, BCBA-D, Endicott College

Why study this topic?

Research Synopses - Biomedical InterventionsDietary interventions for autism (ASD) focus on managing gastrointestinal (GI) symptoms, reducing inflammation, and addressing nutrient deficiencies. Proponents of dietary interventions believe that they can reduce symptoms of autism, such as deregulation of emotions, challenging behavior, and deficits in sustained attention. The dietary interventions examined in this study differ from weight-loss diets. Dietary interventions for autism behavioral and gastrointestinal symptoms, whereas weight loss diets strictly aim to reduce body fat or weight. While a weight loss diet focuses on reducing caloric intake, autism-related diets focus on removing specific irritants (such as gluten or casein) and managing sensory sensitivities.

Examples of specialized dietary approaches include the gluten-free and casein-free (GFCF) diet, the Feingold diet, and the ketogenic diet. The dietary interventions involve excluding foods or food additives from the individual’s diet. The GFCF diet excludes gluten (found in wheat, barley, and rye) and casein (found in dairy). The Feingold diet restricts artificial additives, preservatives, and certain salicylates, aiming to improve hyperactivity and focus. The ketogenic diet reduces the intake of carbohydrates by consuming foods high in fats.

While dietary interventions, such as restrictive diets or supplements, are widely utilized by families of individuals with autism spectrum disorder (ASD), the efficacy of these interventions is debated (Fragaus et al., 2019). In fact, dietary interventions are commonly implemented despite limited comparative evidence on their effectiveness (Srinivasan, 2009). As the interest in dietary interventions continues to exist, it is important to research and examine dietary effects on core symptoms of ASD. Overall, there is no consensus on the efficacy and safety of dietary therapy in children with ASD (Sathe et al., 2017). Matthews and Adams (2023) aimed to address this gap by analyzing perceived benefits, adverse effects, and symptom changes across multiple diet types. In their study, they examined caregiver-reported effectiveness of thirteen therapeutic diets used by individuals with ASD.

What did the researchers do?

In this article, Matthews and Adams (2023) report partial results from a larger survey conducted to recruit caregiver perceptions on the effectiveness of therapeutic diets, nutraceuticals, medications, and therapies for ASD. In this article, they focused on the results for 13 therapeutic diets. Specifically, the authors collected responses from 818 caregivers and some autistic individuals regarding perceived benefits, adverse effects, and overall effectiveness of dietary approaches.

The researchers used a cross-sectional observational design, using data from the survey. The respondents reported on one or more diets and rated the overall benefits and adverse effects of the diets on a 0-4 scale, where a score of 0 meant either no benefit or no adverse effects. A score of 4 indicated a great benefit or adverse effect.

The diets evaluated included the following:

  • Gluten-free/casein-free (GFCF)
  • Feingold diet
  • Ketogenic diet
  • Specific carbohydrate diet
  • Paleo diet
  • Food elimination strategies
  • Healthy diet
  • Casein-free diet
  • Gluten-free diet
  • Low sugar diet
  • Food Avoidance, observation
  • Soy-free diet
  • Corn-free diet
  • Food Avoidance, IgG/IgE

Diets with at least 20 caregiver responses were analyzed, and average scores were then computed across the diet types.

What did the researchers find?

The study found that overall, respondents reported therapeutic diets to be moderately effective interventions for improving symptoms associated with ASD.

Table 1 shows results from the different diets reported by participants. A gluten-free, casein-free diet (GFCF) was reported to be the most common diet, followed by a general healthy diet, casein-free diet alone, and gluten-free diet alone. Overall scores for each diet were calculated by averaging the ratings obtained from the respondents. A Net Benefit score was calculated by finding the difference between the Overall Benefit and Overall Adverse Effect score. Looking closely at the overall Net Benefit score, moderate effects were reported.

Table 1. Results reported by participants from different diets

Diet Number of Respondents Who Used a Diet Overall Benefit Overall Adverse Effect Net Benefit
GFCF Diet 221 2.4 0.1 2.3
Healthy Diet 179 2.7 0 2.7
Casein-Free Diet 134 2.2 0.1 2.1
Gluten-Free Diet 114 2.0 0.1 1.9
Low Sugar Diet 104 2.5 0.1 2.4
Food Avoidance, observation 82 2.5 0.3 2.2
Feingold Diet 74 2.6 0 2.6
Soy-Free Diet 62 2.1 0 2.1
Food Avoidance, IgG/IgE 54 2.6 0 2.6
Corn-Free Diet 46 2.2 0 2.2
Specific Carbohydrate Diet 37 2.4 0.2 2.2
Ketogenic Diet 21 2.4 0.4 2.0
Paleo Diet 21 2.1 0 2.1

Strengths and Limitations of the Study

A primary strength of the study was the large and diverse sample of participants. The authors recruited 818 respondents, which provides a broad snapshot of caregiver experiences across the United States. This large dataset exceeds that of many prior diet-related autism surveys. Secondly, the authors examined thirteen diets that offer valuable descriptive data about relative perceived effectiveness. Thirdly, the study provides reported caregiver use of dietary interventions, thus capturing interventions that may not yet be extensively studied in clinical trials. Furthermore, the study recruited perceptions about both beneficial and adverse effects of the various diets.

Despite its contributions, the study has methodological weaknesses that limit causal interpretation. It is important to note that the dietary data were extracted from a larger survey that also examined medications and other therapies. Extracting and isolating specific data from the larger data is a concern because it does not clearly contextualize how dietary interventions compared with other interventions. In the absence of the full picture, it is difficult to determine whether diets were perceived as more effective, less effective, or similarly effective than other commonly used ASD interventions. The “benefit” scores for diets may appear meaningful in isolation, but without comparative data, it is difficult to judge their relative clinical significance.

A second major limitation of the study is that all the data collected is based on caregiver perceptions. In other words, no objective measures were taken from the respondents. Generally, self-report survey results are vulnerable to expectation effects (where what you anticipate happening directly shapes your experience), confirmation bias (the tendency to see change that supports those expectations), and placebo effects (where an ineffective treatment produces measurable improvements simply because the person believes it will work (Akbulut, 2025). These concerns and considerations would apply to any research study that relies on self-report data. The absence of standardized assessments means that reported improvements cannot be verified. With respect to statements related to causality, there is a lack of experimental control. As stated above, the study did not look at factors such as duration, consistency, and fidelity. Further, respondents may have simultaneously used multiple diets, medications, and/or supplements, as well as other unreported behavioral or educational therapies. Thus, observed improvements cannot be attributed specifically to dietary interventions.

Although it may seem that the diets had therapeutic effects, a close look at the results shows that average ratings were in the middle/moderate range. The authors do not report specific data on the number of respondents who reported negatively about the diets. Reporting average ratings underscores the importance of individual experiences and creates an impression that no significant side effects result from the use of diets. Also, there is little information provided about what other interventions the individuals received that could have accounted for the reported results (both benefits and adverse effects).

Additionally, there is unequal representation of the diets evaluated. Some dietary approaches had relatively small numbers of respondents, which reduces the reliability of comparisons and may inflate perceived effectiveness due to sampling variability. The study does not adequately control for confounding factors such as socioeconomic status, severity of autism symptoms, or co-occurring medical conditions that could influence both diet selection and perceived improvement.

Despite the authors’ contention that special diets are inexpensive, dietary interventions can be costly, restrictive, and socially burdensome. Some approaches risk nutritional deficiencies if not medically supervised. Thus, strong claims about effectiveness should be made cautiously. On the positive side, many diets evaluated involve generally healthy eating patterns, which may improve overall well-being regardless of autism-specific effects.

What do the results mean?

Existing research on dietary interventions for autism remains mixed and generally inconclusive. Reviews of clinical trials often note modest or inconsistent effects and call for more rigorous research designs. Dietary changes may benefit specific subgroups, particularly those with gastrointestinal problems, demonstrated nutritional deficiencies, or food allergies and sensitivities, but universal recommendations are not supported by current evidence.

This study provides a useful descriptive overview of caregiver perceptions regarding therapeutic diets for autism. The study’s strengths lie in its large sample, comparative approach, and real-world relevance. However, its methodological limitations, such as reliance on self-report and lack of experimental control, substantially restrict conclusions about efficacy. Rather than focusing on limitations and dismissing the potential of this study, it may be best to interpret these results as exploratory and hypothesis-generating. They highlight the need for well-designed randomized controlled trials to determine which dietary interventions, if any, produce reliable improvements in ASD-related outcomes.

A strength of the Matthews and Adams article is that it reflects what families actually try in community settings and suggests that some diets may be perceived as helpful and relatively low risk. The study provides useful descriptive evidence that many caregivers perceive therapeutic diets as beneficial and relatively low in adverse effects. The study provides descriptive data on the real-world use of dietary interventions for autism and highlights the prevalence of nutritional approaches among families seeking complementary treatments. Its large sample size and comparative analysis across multiple diets provide a useful overview of caregiver experiences and perceived outcomes. In addition, including ratings of adverse effects strengthens the study by acknowledging potential negative outcomes and enabling comparisons with other intervention categories such as medications and supplements.

References:

Akbulut, Y. (2025). Beyond self-reports: Addressing bias and improving data quality in educational research. Journal of Measurement and Evaluation in Education and Psychology, 16(2), 115-123. https://doi.org/10.21031/epod.1630477

Fraguas, D., Díaz-Caneja, C. M., Pina-Camacho, L., Moreno, C., Durán-Cutilla, M., Ayora, M., González-Vioque, E., de Matteis, M., Hendren, R. L., Arango, C., & Parellada, M. (2019). Dietary interventions for autism spectrum disorder: A meta-analysis. Pediatrics, 144(5), e20183218. https://doi.org/10.1542/peds.2018-3218

Matthews, J. S., & Adams, J. B. (2023). Ratings of the effectiveness of 13 therapeutic diets for autism spectrum disorder: Results of a national survey. Journal of Personalized Medicine, 13(10), 1448. doi: 10.3390/jpm13101448

Sathe, N., Andrews, J. C., McPheeters, M. L., & Warren, Z. E. (2017). Nutritional and dietary interventions for autism spectrum disorder: A systematic review. Pediatrics, 139(6), e20170346. https://doi.org/10.1542/peds.2017-0346

Srinivasan, P. (2009). A review of dietary interventions in autism. Annals of Clinical Psychiatry, 21(4), 237-247. https://doi.org/10.1177/104012370902100405

Subar, A. F., Freedman, L. S., Tooze, J. A., Kirkpatrick, S. I., Boushey, C., Neuhouser, M. L., Thompson, F. E., Potischman, N., Guenther, P. M., Tarasuk, V., Reedy, J., & Krebs-Smith, S. M. (2015). Addressing current criticism regarding the value of self-report dietary data. The Journal of Nutrition, 145(12), 2639-2645. https://doi.org/10.3945/jn.115.219634.

Reference for this article

McKenna, K., & Marya, V. (2026). Research synopsis: Ratings of the effectiveness of 13 therapeutic diets for autism spectrum disorder: Results of a national survey. Science in Autism Treatment, 23(6).

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