A new study from Turkey adds to evidence that vitamin D deficiency is significantly higher in children and adolescents with autism spectrum disorders (ASD) than in the general population.

Esma Şengenç and colleagues measured serum 25-hydroxyvitamin D (25-OHD) levels in 1,529 children and teens with ASD. In addition, they analyzed calcium, phosphorus, alkaline phosphatase, and 25-OHD levels of 100 of these individuals, comparing them to a neurotypical control group.

The researchers say they detected vitamin D deficiency or insufficiency in approximately 95% of the individuals with ASD. Of these, 58% had vitamin D deficiency and 13% had severe deficiency. Levels of vitamin D were significantly lower in adolescents with ASD than in children younger than 11 years of age.

The researchers say, “Additionally, the mean serum 25-OHD level, which is a measurable indicator of vitamin D, was significantly lower in children and adolescents with autism than in healthy controls.” Individuals with ASD also had significantly higher levels of alkaline phosphatase, a marker for vitamin D deficiency.

The researchers note that several earlier studies (although not all) have shown lower vitamin D levels in children with ASD compared to neurotypical peers. They conclude, “Monitoring vitamin D levels is crucial in autistic children, especially adolescents, to take protective measures and treat this condition early.”

“Vitamin D levels in children and adolescents with autism,” Esma Şengenç Ertuğrul Kıykım, and Sema Saltik, Journal of International Medical Research, Vol. 48, No. 7, July 15, 2020 (free online). Address: Esma Şengenç, Department of Pediatrics, Cerrahpasa Medical Faculty, Istanbul UniversityCerrahpasa, No. 53 Koca Mustafapasa St, Istanbul, 34096, Turkey. [email protected]

This article originally appeared in Autism Research Review International, Vol. 34, No. 3, 2020