A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Winter, 2016 | Number 1, Volume 30

Can vitamin D supplementation reduce ASD recurrence rate?

Vitamin D supplementation during prenatal development and early childhood may reduce the risk of autism spectrum disorders (ASD) in siblings of children with the condition, a small study funded by the Autism Research Institute suggests. 

Gene Stubbs and colleagues prescribed vitamin D (5000 IU per day) to 19 pregnant women who already had one or more children with autism. All of the women were in their first, second, or early third trimester of pregnancy, and only two of them were overtly deficient in vitamin D before receiving supplementation. 

In addition, the researchers supplemented the women’s infants with vitamin D (1000 IU per day) from birth to their third birthday. The children were assessed for autism at 18 and 36 months of age. 

The researchers say, “The final outcome was 1 out of 19 (5%) developed autism in contrast to the recurrence rate of approximately 20% in the literature.” They add, “We also found support for previous studies showing that vitamin D may reduce the incidence of preterm births, small-for-dates, and pre-eclampsia [a serious complication of pregnancy].” 

Stubbs and colleagues comment, “Our preliminary impression is that the best outcome for the children of mothers who get pregnant is for the mothers to be vitamin D ‘replete’ during the periconceptual period, that is, to have the optimal level of vitamin D at least two months before the mother gets pregnant.” 

The researchers say that while their results are promising, this was a small study with no controls and their results will need to be replicated.


“Autism: Will vitamin D supplementation during pregnancy and early childhood reduce the recurrence rate of autism in newborn siblings?” G. Stubbs, K. Henley, and J. Green, Medical Hypotheses, Vol. 88, 2016 (online). Address: Gene Stubbs, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, [email protected].