Efficacy of Vitamin Supplements in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by repetitive patterns of behavior, communication problems, and poor social interaction. A pharmacologic treatment approach for the main symptoms of ASD has not been developed. This has led families suffering from ASD to seek alternative therapeutic approaches. Since children with ASD often exhibit picky eating behaviors resulting in vitamin and mineral deficiencies, some nutritional interventions, especially the use of supplements, have recently gained attention. Accordingly, scientists have examined the effects of certain nutrients on ASD symptoms and signs. This text reviews the effects of some vitamins on symptoms and signs associated with ASD. The role of vitamin A in neurodevelopment has been supported by many studies. Retinoic acid can influence the migration of neurons into the cerebral cortex and provides gamma aminobutyric acid for neuronal firing. GABAergic signaling pathway abnormality is one of the processes contributing to the pathogenesis of ASD. Vitamin D is known to reduce reactive oxygen species and inflammation by promoting glutathione synthesis. It has also been reported to improve nerve growth factor and brain-derived neurotrophic factor levels impaired in ASD. The effects of vitamins involved in one-carbon metabolism (vitamins B12, B6, and folic acid) on ASD have also been the subject of research. High homocysteine levels during pregnancy negatively affect expressive language and gross motor areas and reduce psychomotor ability. Adequate catalysis function of the enzymes in which these vitamins act as cofactors prevents high homocysteine levels. Finally, the efficacy of vitamins C and E in protecting against neurotoxicity, neuroinflammation, and neurodegeneration has also been demonstrated. Although all these vitamins are known to have very important roles in neurodevelopment, their use as supplements in ASD requires serious awareness. Autism is a metabotypically heterogeneous condition, so the endophenotype of the individual with ASD should be taken into account. It may be useful to carry out retrospective metabolic studies to identify individuals who respond to specific treatments. Thus, ASD subgroups can be identified for specific vitamin supplementation.