The neurodevelopmental illness known as autism spectrum disorder (ASD) has a complex etiology. Vitamin/mineral and targeted vitamin therapy trials have been prompted by the numerous reports of nutritional deficiencies and altered metabolism (oxidative stress, methylation abnormalities, immunological dysregulation) in ASD. Goal: Examine clinical data on vitamin-based and multivitamin therapy for core and related symptoms of ASD, summarizing safety, mechanisms, and suggestions for study and practice. Methods: Narrative evidence synthesis with a focus on large observational studies, systematic reviews/meta-analyses, and randomized controlled trials (RCTs). Results: Following multivitamin or tailored vitamin therapy (e.g., folinic acid, methyl cobalamin, vitamin D), small RCTs and a number of mechanistic and cohort studies indicate improvements in metabolic biomarkers and, in certain trials, clinician-rated or parent-reported symptoms. In observational studies and meta-analyses, prenatal folic acid/multivitamin consumption is consistently linked to a lower child risk of ASD. The overall quality of the data is inconsistent: there aren't many big, long-term RCTs, and conclusions can't be drawn with certainty because to differences in populations, supplements, dosage, and outcome measures. At conventional dosages, safety statistics are typically positive; nevertheless, large doses (or imbalanced supplements) have potential and actual dangers that need to be monitored.
Kumar et al. (2026) studied this question.