Prospective cohort study of vitamin D and autism spectrum disorder diagnoses in early childhood.
Preschool vitamin D levels do not forecast autism, so routine supplementation is not a proven shield.
01Research in Context
What this study did
Ali et al. (2019) followed 3,852 preschoolers for several years. They checked each child’s blood vitamin D level and noted who took vitamin pills.
The team wanted to know if low vitamin D or extra pills predicted an autism diagnosis later on.
What they found
Kids with low vitamin D were diagnosed with autism at the same rate as kids with high vitamin D. Giving children vitamin pills did not lower the odds of autism.
The numbers stayed flat—no link in either direction.
How this fits with other research
Kočovská et al. (2012) warned that earlier studies were tiny and weak. Yamna’s large cohort fills that gap and backs up the call for better data.
Green et al. (2020) also found no link, but they looked at moms’ vitamin D during pregnancy instead of the child’s. Both windows—prenatal and preschool—point to the same null result.
Whitehouse et al. (2013) saw a small bump in attention-switching problems when moms were low in vitamin D. Yamna saw nothing for full autism, showing the earlier signal was narrow, not broad.
Why it matters
You can stop telling families that vitamin D pills will prevent autism. Check nutrition for general health, but don’t sell it as an ASD shield. Focus your energy on evidence-based teaching strategies instead.
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02At a glance
03Original abstract
Several studies have suggested an association between vitamin D in childhood and autism spectrum disorder. No prospective studies have evaluated whether lower vitamin D levels precede ASD diagnoses - a necessary condition for causality. The objective of this study was to prospectively evaluate whether vitamin D serum levels in early childhood was associated with incident physician diagnosed ASD. A prospective cohort study was conducted using data from preschool-aged children in the TARGet Kids! practice-based research network in Toronto, Canada, from June 2008 to July 2015. 25-hydroxyvitamin D concentration was measured through blood samples and vitamin D supplementation from parent report. Autism spectrum disorder diagnosis was determined from medical records at follow-up visits. Covariates included age, sex, family history of autism spectrum disorder, maternal ethnicity, and neighborhood household income. Unadjusted and adjusted relative risks and 95% confidence intervals were estimated using Poisson regression with a robust error variance. In this study, 3852 children were included. Autism spectrum disorder diagnosis was identified in 41 children (incidence = 1.1%) over the observation period (average follow-up time = 2.5 years). An association between 25-hydroxyvitamin D concentration and autism spectrum disorder was not identified in the unadjusted (relative risk = 1.04, 95% confidence interval: 0.97, 1.11 per 10 nmol/L increase in 25-hydroxyvitamin D concentration) or adjusted models (adjusted relative risk = 1.06; 95% confidence interval: 0.95, 1.18). An association between vitamin D supplementation in early childhood and autism spectrum disorder was also not identified (adjusted relative risk = 0.86, 95% confidence interval: 0.46, 1.62). Vitamin D in early childhood may not be associated with incident physician diagnoses of autism spectrum disorder.
Autism : the international journal of research and practice, 2019 · doi:10.1177/1362361318756787