Gut microbiota, vitamin A deficiency and autism spectrum disorder: an interconnected trio - a systematic review.

This review looked at how gut bacteria, vitamin A levels, and autism might be connected. Researchers found that children with autism consistently have different gut bacteria compared to other children. They also found that children with autism often have lower vitamin A levels, which might contribute to autism symptoms. The study suggests that vitamin A supplements could potentially help reduce autism symptoms, though more research is needed.

This systematic review examined connections between autism spectrum disorder, gut microbiota alterations, and vitamin A deficiency by analyzing 19 studies from 2010-2022. The review found consistent evidence of significant gut microbiota changes in autistic individuals, suggesting these alterations could serve as biomarkers for autism. Notably, no significant differences in gut microbiota composition were found between autistic individuals and those with vitamin A deficiency, indicating vitamin A deficiency may contribute to autism development rather than result from it. The review also identified reduced retinoic acid levels in autistic children, which may correlate with symptom severity, highlighting vitamin A supplementation as a potential therapeutic intervention.

Findings support routine assessment of vitamin A status in autistic children and consideration of supplementation as adjunct therapy. Gut microbiota profiling may offer diagnostic value. Early nutritional interventions, particularly vitamin A supplementation, warrant investigation as preventive or therapeutic strategies for autism symptoms.

Only 19 studies included in analysis. Sample sizes not reported for individual studies. Limited timeframe (2010-2022) may have excluded relevant earlier research. Causal relationships between vitamin A deficiency and autism onset cannot be definitively established from available evidence.

Accumulating evidence proves that children with autism have gastrointestinal problems. However, a significant difference in gut microbiota (GM) exists between autistic and non-autistic children. These changes in the GM may stem from several factors. Recently, researchers focused on nutritional factors, especially vitamin deficiency.

Thus, our systematic review investigates the connections among autism, GM alterations, and vitamin A deficiency (VAD), by analyzing studies sourced from PubMed and Embase databases spanning from 2010 to 2022. Adhering to PRISMA guidelines, we meticulously selected 19 pertinent studies that established links between autism and GM changes or between autism and VAD. Our findings uniformly point to significant alterations in the GM of individuals with autism, indicating these changes as promising biomarkers for the disorder. Despite the consistent association of GM alterations with autism, our analysis revealed no notable differences in GM composition between individuals with autism and those experiencing VAD.

This suggests that VAD, especially when encountered early in life, might play a role in the onset of autism. Furthermore, our review underscores a distinct correlation between reduced levels of retinoic acid in children with autism, a disparity that could relate to the severity of autism symptoms. The implications of our findings are twofold: they not only reinforce the significance of GM alterations as potential diagnostic markers but also spotlight the critical need for further research into nutritional interventions. Specifically, vitamin A supplementation emerges as a promising avenue for alleviating autism symptoms, warranting deeper investigation into its therapeutic potential.