There’s a growing body of evidence suggesting Vitamin D plays an important role in regulating serotonin. This means it could cause (deficiency) or treat Autism Spectrum Disorder (ASD) symptoms (supplement). For instance, one study prescribed Vitamin D3 to autistic children in an open trial and had a 80% success rate – that is, the children became less hyperactive, irritable, and engaged far less in stereotypical behavior. The children were also more responsive and compliant to their families.


Vitamind D is produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Image: Mercola

In the US, one in 68 kids is affected by ASD, making the fastest growing development disorder in the country. Studies so far have garnered that the condition is caused by both genetic and environmental factors. Among the latter, Vitamin D3 (cholecaliferol) seems to play a significant role. The prohormone is naturally released in the body when exposed to sunlight. Previously, Patrick and Ames published a paper in which they show the vitamin D hormone (calcitriol) activates the transcription of the serotonin-synthesizing gene tryptophan hydroxylase 2 (TPH2). This suggests that a specific level of vitamin D may be required to produce adequate serotonin, a neurotransmitter thought to affect social behavior. The paper also explains 4 major characteristics associated with autism: the low concentrations of serotonin in the brain and its elevated concentrations in tissues outside the blood-brain barrier; the low concentrations of the vitamin D hormone precursor 25-hydroxyvitamin D [25(OH)D3]; the high male prevalence of autism; and the presence of maternal antibodies against fetal brain tissue.

The scientists in Egypt prescribed Vitamin D3 supplements (300 IU/Kg/day not to exceed 5,000 IU/day) to 122 autistic children aged between three to nine years. The treatment was administered for three months, then compared to a control group. Once in the liver, Vitamin D3 is converted into 25-hydroxyvitamin D3. Despite side-effects including skin rashes, itching and diarrhea, 80% of the children involved in the study fared better at CARS scores, which gauges the severity of ASD symptoms. Findings appeared in Nutritional Neuroscience.

Elsewhere, doctors in China are reporting that treatment with vitamin D appeared to produce dramatic improvements in a toddler with autism. Blood tests showed that the boy had borderline low blood levels of vitamin D (12.5 ng/mL). The doctors administered a monthly injection of vitamin D3 (150,000 IU) and prescribed a daily oral supplement (400 IU). After two months, the boy’s vitamin D blood levels had risen to 81.2 ng/mL, and his parents were reporting clear improvements. The boy had stopped running in circles and banging his head. He was responding to his name, playing with toys and asking his parents to hold him in their arms.

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Dr. John J Cannell is the founder of the Vitamin D council in the United States, and one of the supporters of the study’s findings made in Egypt. Cannell met lead author  Khaled Saad while seeking more related information about Patrick & Ames study. 

“My experience, having treated about 100 children with autism, is that 25% respond dramatically to high dose vitamin D, 50% respond significantly and 25% do not respond at all I don’t know why,” Cannell said for ZME Science. “80% of the children responded to 5,000 IU/day so it is about what I have found. My hopes for the future is that a randomized controlled trial is done using high dose vitamin D,” he added.

Regarding a randomized trial for Vitamind D3 and autism – the golden standard typically employed for determining causal relationships – Cannell doesn’t express much hope.

“Unfortunately, the trial will probably be negative for two reasons. They will not use enough vitamin D and, two, their ethics committee will not allow the placebo group to remain deficient thus rendering the trial useless,” Cannell said.

Cases of children diagnosed with autism spectrum disorders (ASDs) increased by 30% in the last couple of years, according to a reported issued by the  Centers for Disease Control and Prevention. A piece I wrote previously for ZME Science argues that autism might not actually be on the rise and the increased prevalence might actually be a statistical mishap due to under-reporting and the way doctors have changed what falls under an ASD diagnosis. As far as Cannell is concerned, he believes “the prevalence of autism is increasing in direct proportion to sun avoidance, which is still increasing.”

Hopefully, we might actually see some results from some randomized trials, maybe made in the US. A lot of parents go bankrupt to treat their kids, with roughly $60,000 expenses a year on average per family. Vitamin D is as inexpressive as sunlight.