Associations Between Vitamin D and Core Symptoms in ASD: An Umbrella Review

: We conducted an umbrella evaluation to quantitatively synthesize previous systematic reviews and meta-analyses, thereby collating evidence on the association between vitamin D and core symptoms in people with autism in anticipation of informing clinical vitamin D supplementation. Based on the pre-established protocol, we ended up with 9 studies. Based on rigorous analysis, we found that vitamin D deficiency early in life is a risk factor for the development of ASD and that vitamin D supplementation improves the core symptoms of ASD. Our study concludes that vitamin D supplementation is beneficial for individuals with autism, that vitamin D deficiency early in embryonic life increases the risk of ASD, and that our study supports the idea that prevention begins with vitamin D supplementation early in life. At the same time, we must recognize that our current conclusions support the benefits of vitamin D supplementation for children with ASD, but we are unable to determine the causal relationship, ie, how vitamin D works in ASD, and we need more basic research to explore the mechanisms involved.