Effects of vitamin D supplementation on core symptoms, serum serotonin and interleukin 6 in children with autism spectrum disorders: A Randomized Clinical Trial

Abstract Objectives Children with Autism spectrum disorders (ASD) have lower serum vitamin D and higher serotonin and interleukin (IL)-6 in comparison with healthy children. The aim of this study is to evaluate the effect of vitamin D on core symptoms and serum levels of serotonin and IL-6 in these children. Methods This parallel randomized double-blind, placebo-controlled trial was conducted on 43 children with ASD (7 girls and 36 boys; 8.91±2.87 years old). Children were randomly allocated to receive either vitamin D drop (300 IU/kg/day up to a maximum of 6000 IU/day) or placebo for 15 weeks. Serum levels of 25(OH)D, IL-6 and serotonin were measured at the baseline and the end of the trial. Also, the severity of autism and the social and individual maturity of children were measured by the childhood autism rating scale (CARS), the autism treatment assessment checklist (ATEC), and aberrant behavior Checklist-community (ABC-C) questionnaires before and after intervention. Randomization and allocation to groups were done using computer generated numbers. Results Above 86% of patients had vitamin D deficiency at the beginning of the study. Serum level of 25(OH)D increased significantly in vitamin D group (P=0.001). The clinical symptoms of autism measured by CARS and ATEC scales were alleviated significantly (P= 0.021 and P= 0.020, respectively); however the serum levels of serotonin and IL-6 and the scale of ABC-C remained without a significant change. Conclusion These findings suggest that vitamin D supplementation may improve ASD symptoms; however more studies with longer duration are indispensible to confirm our results.