Prebiotics and probiotics for autism spectrum disorder: a systematic review and meta-analysis of controlled clinical trials.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder. The discovery of the influence of gut microbiota on mental illness opens up new research avenues for the role of gut microbiota modifiers, such as probiotics or prebiotics, as a potential course of treatment. Potential treatments have received considerable attention in recent years. The meta-analysis only included clinical controlled trials to explore whether probiotics and prebiotics can improve the overall severity of ASD symptoms in children, the severity of gastrointestinal (GI) problems and the comorbid psychopathlology in ASD. Although systematic reviews have been conducted in this area in the past, most of them are mixed experimental designs, and the reliability of the conclusions remains to be determined. To the best of our knowledge, no systematic review of randomized controlled trials (RCTs) has been conducted. A meta analysis used a combination of subject terms and free words, or used keywords, titles, and abstracts to conduct in PubMed, Web of Science, Embase, and Cochrane Library to identify studies relevant to the current review. The results of the meta-analysis showed that probiotics and prebiotics did not significantly improve the severity of ASD patients, GI problems and comorbid psychopathlology in ASD, and the result is contradictory to the previous literatures. Since there are relatively few clinical controlled trials that can be included, the results of this study still need to be further verified in the clinic. In the future, more randomized controlled studies, more research populations, and the use of more professional clinicians may provide more robust research results.