Researchers in the Netherlands and China released a meta-analysis of the 11 studies published to date on serum 25(OH)D and autism spectrum disorder (ASD or autism).
Wang T, Shan L, Du L, Feng J, Xu Z, Staal WG, Jia F. Serum concentration of 25-hydroxyvitamin D in autism spectrum disorder: a systematic review and meta-analysis. Eur Child Adolesc Psychiatry. 2015 Oct 29.
Previous research discovered that low vitamin D levels in autistic individuals are inherited, just as I predicted.
Also, researchers recently discovered that some of the genes that control vitamin D metabolism are associated with autism. They found that two of the genes involved in the vitamin D receptor are linked with autism. In addition, they discovered that the gene that makes the enzyme that first metabolizes vitamin D in the liver, the 25-hydroxylase, is also associated with autism.
Schmidt RJ, Hansen RL, Hartiala J, Allayee H, Sconberg JL, Schmidt LC, Volk HE, Tassone F. Selected vitamin D metabolic gene variants and risk for autism spectrum disorder in the CHARGE Study. Early Hum Dev. 2015 Aug;91(8):483-9.
This first meta-analysis of the 11 studies compared the vitamin D levels in children with ASD to children without the disorder. The researchers reported that 7 of the studies found that the control groups had significantly higher 25(OH)D levels than the children with autism.
Overall, even with the four negative studies, the overall difference ratio of the 11 studies was over 8.
Remember, there is now a case report and a case series (80 children) showing vitamin D helps autism, sometimes dramatically. A case series is a type of study that tracks subjects with a known exposure (i.e. vitamin D) and assesses the outcome (i.e. autism).
If you know an individual with autism, even mild autism, I recommend they take enough vitamin D to achieve a vitamin D blood status in the upper ranges of normal (about 80 ng/ml). This is best accomplished with a combination of safe, sensible sun-exposure (when feasible) and oral vitamin D supplementation. Take the first 5,000 IU/day as three capsules of D3Plus. For parents of young children, simply cut capsules in two with a scissors and dissolve contents in applesauce or blend in a smoothie. Then, if they have their vitamin D levels tested and in 3 months have determined that they have not reached a level near 80 ng/ml, take additional vitamin D3 as needed.
To prevent autism, pregnant women should take 5,000 to 10,000 IU/day during pregnancy but do not stop there. Make sure the infant and toddler get supplemental vitamin D, about 1,000 Iu/day for every 25 pounds of body weight. (Ddrops is easy to use in infancy and toddlerhood.)
For all 85 blogs that I have written since 2007 discussing the role of vitamin D in autism, click here.