Impact of Low Vitamin D on Social Behavior Associated with Autism

​Vitamin D, tryptophan and omega-3 to boost brain serotonin during pregnancy and beyond

This new study, Vitamin D hormone regulates serotonin synthesis. Part 1: relevance for autism (2013) by Dr. Ames and Rhonda Patrick demonstrates the impact of low vitamin D status on social behavior associated with autism spectrum disorders (ASD). The hormones serotonin, oxytocin, and vasopressin are all activated by vitamin D (which itself is a hormone).

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​Vitamin D activates the enzyme TPH2 (tryptophan hydroxylase 2) that converts tryptophan to serotonin –  the calming neurotransmitter in the brain. Vitamin D inhibits TPH1, which reduces serotonin in the gut and elsewhere, thus reducing inflammation.  

​The study’s authors propose that in addition to vitamin D, mothers and children should take extra tryptophan and omega-3 fatty acids to boost brain serotonin.  I couldn’t agree more.  In pregnancy you should absolutely take 5000 IU’s of vitamin D daily along with your prenatal vitamins and omega-3 supplements, and with this study’s information, I would add tryptophan to that list.

​Below is the abstract which is technical and detailed, but best read as written:​
“Serotonin and vitamin D have been proposed to play a role in autism; however, no causal mechanism has been established. Here, we present evidence that vitamin D hormone (calcitriol) activates the transcription of the serotonin-synthesizing gene tryptophan hydroxylase 2 (TPH2) in the brain at a vitamin D response element (VDRE) and represses the transcription of TPH1 in tissues outside the blood-brain barrier at a distinct VDRE. The proposed mechanism 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. Two peptide hormones, oxytocin and vasopressin, are also associated with autism and genes encoding the oxytocin-neurophysin I preproprotein, the oxytocin receptor, and the arginine vasopressin receptor contain VDREs for activation. Supplementation with vitamin D and tryptophan is a practical and affordable solution to help prevent autism and possibly ameliorate some symptoms of the disorder.”