The Association between Vitamin D Status and Autism Spectrum Disorder (ASD): A Systematic Review and Meta-Analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational (case-control and prospective) studies
PubMed 33383952 · doi:10.3390/nu13010086
What was done
A systematic review and meta-analysis of literature from PubMed, EMBASE, Web of Science, and Cochrane Library evaluated the association between vitamin D status and autism spectrum disorder (ASD). Investigators pooled mean differences (MD) in vitamin D concentration and odds ratios (OR) for ASD using random-effects models across 34 publications with 20,580 participants.
What was found
- Case-control studies (24 studies) showed children and adolescents with ASD had significantly lower vitamin D concentrations compared to controls (MD: -7.46 ng/mL, 95% CI: -10.26 to -4.66, p < 0.0001, I² = 98%). - Lower vitamin D was associated with higher risk of ASD across 10 case-control studies reporting odds ratios (OR: 5.23, 95% CI: 3.13 to 8.73, p < 0.0001, I² = 78.2%). - Analysis of maternal and neonatal vitamin D showed a trend toward lower early-life concentrations in ASD cases (MD: -3.15 ng/mL, 95% CI: -6.57 to 0.26, p = 0.07, I² = 99%). - Prospective studies showed reduced maternal or neonatal vitamin D was associated with a higher likelihood of ASD (OR: 1.54, 95% CI: 1.12 to 2.10, p = 0.0071, I² = 81.2%).
Why it matters
This review synthesizes observational evidence showing that both early-life and childhood vitamin D deficiencies correlate with ASD. It highlights maternal and neonatal vitamin D status as potential targets for prospective intervention research.
Limits
The included literature consists of observational designs (primarily case-control), precluding causal inference and leaving open reverse causality (such as dietary restrictions or reduced sunlight exposure in ASD). Heterogeneity across all meta-analyses was extremely high (I² = 78.2% to 99%).
Cited by
- supports Vitamin D deficiency during pregnancy disrupts serotonin production, which may affect autism risk.