Metagenomics study suggests the role of vitamins and gut microbiome in autism spectrum disorder

Introduction: Autism is a neurological disability that often appears after the age of three in children, also known as an Autism Spectrum Disorder (ASD). Several studies have examined the influence of some environmental factors, and many parameters related to the behavior of autistic patients have been measured in order to find ways to reduce ASD. This study investigates the relationship between ASD and serum levels of vitamin D3, B12, folic acid, and the gut microbiome. Methods: The serum levels of vitamin D3, B12, and folic acid in ASD patients were measured by the ELISA method and compared to healthy groups. DNA was extracted from stool samples of ASD patients and the control group, and then the gut microbiome was investigated via a metagenomics approach. Metagenomics sequencing was performed to analyze the 16S rRNA gene sequencing for phylum and sub phylum level microbiome. Result: The result showed no significant change in the VitD3 and folate levels of ASD patients compared to the control group (p=0.157 and p=0.0505, respectively). There was a significant difference in the VitB12 level between control healthy individuals and ASD patients, in which the serum VitB12 concentration was significantly lower than the control group (p=0.0001). Our results regarding gut metagenomics showed that the abundance of the Actinobacteria by the phylum level were significantly higher in the ASD patients compared to the control group (p=0.0013). The abundance of the Firmicutes by the phylum level were significantly lower in the ASD patients compared to the control group (p=0.0016).The abundance of Bifidobacteriaceae, and Ruminococcaceae by the family level were significantly higher in the ASD patients compared to the control group (p=0.0004. and p=0.0489, respectively).Our results indicated less species richness in the ASD patients compared to the control group. Conclusion: Patients with ASD have lower serum levels of vitamin B12 and different gut microbiome compared to healthy controls. Low vitamin B12 levels and altered gut microbiome are significantly associated with ASD in this study. However, further research is needed to determine whether these factors could serve as predictors of severe outcomes in ASD.