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Lack of effect of vitamin D3 supplementation in autism: a 20-week, placebo-controlled RCT
  1. Conor P Kerley1,
  2. Clare Power1,
  3. Louise Gallagher2,3,
  4. David Coghlan1
  1. 1 Department of Paediatric Medicine, National Children’s Hospital, Dublin, Ireland
  2. 2 Department of Psychiatry, Trinity College Dublin, Dublin, Ireland
  3. 3 Trinity Translational Medicine Institute, St. James’s Hospital, Dublin, Ireland
  1. Correspondence to Dr Conor P Kerley, Department of Paediatric Medicine, National Children’s Hospital, Tallaght, Dublin 24, Ireland; conorkerley{at}


Objectives Data suggest a potential role for vitamin D in autism spectrum disorder (ASD). We wanted to assess the effect of vitamin D3 supplementation compared with placebo in children with ASD.

Design This was a double-blind, randomised, placebo-controlled trial.

Setting A paediatric outpatient centre at high latitude over the winter season in Dublin, Ireland (53°N).

Patients 42 children with ASD.

Interventions 2000 IU vitamin D3 supplementation or placebo daily for 20 weeks.

Main outcome measures Assessments were completed at baseline and after 20 weeks of supplementation. The primary outcome was the stereotypic behaviour subscale from the Aberrant Behaviour Checklist (ABC). Secondary exploratory outcomes included additional subscales from the ABC, the Social Responsiveness Scale and rating on the Developmental Disabilities—Children’s Global Assessment Scale (DD-CGAS) as well as biochemical parameters of total vitamin D status (25-hydroxyvitamin D (25(OH)D)), immunity and systemic inflammation.

Results 38 children completed the trial. Baseline 25(OH)D was 54.2±19.7 nmol/L. Following vitamin D3 supplementation, there was a significant increase in 25(OH)D to 83.8 nmol/L (p=0.0016) but no effect on the primary endpoint. However, there was an improvement in self-care on DD-CGAS (p=0.02). In contrast, there was also a trend toward decreased inappropriate speech in the placebo group (p=0.08).

Conclusion Vitamin D supplementation had no effect on the primary outcome with limited and inconsistent effects in children with ASD. Considering the other promising data as well as the relative safety and cheapness of vitamin D supplementation, further trials are warranted.

Trial registration NCT02508922.

  • Vitamin D
  • autism spectrum disorder
  • communication
  • behavior
  • symptoms
  • inflammation

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  • Contributors CPK conceptualised and designed the study and data collection instruments, coordinated and supervised data collection, carried out the initial analyses, drafted the initial manuscript and approved the final manuscript as submitted. CP reviewed, coordinated and supervised data collection; revised the manuscript and approved the final manuscript as submitted. LG designed the data collection instruments and approved the final manuscript as submitted. DC conceptualised and designed the study, carried out the initial analyses and approved the final manuscript as submitted.

  • Funding This trial was supported by funding from the National Children’s Hospital Foundation, Ireland. The funding body had no involvement instudy design, data collection, analysis or interpretation.

  • Competing interests None declared.

  • Patient consent Guardian consent obtained.

  • Ethics approval Research Ethics Committee of the National Children’s Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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