The brain produces three hormones that influence social behavior: People with autism spectrum disorder (ASD) often have less of these hormones in their brains, a situation that may be the reason autistic patients often have difficulty with social interactions. A study from researchers in California has discovered that vitamin D stimulates the production of these hormones. Further study is needed to determine if vitamin D supplements during pregnancy and after ASD diagnosis may help lower the risk or ease symptoms of autism.
Drs. Rhonda Patrick and Bruce Ames, of the Children’s Hospital Oakland Research Institute (CHORI) knew that low levels of both serotonin and vitamin D were associated with ASD but, until their study, no medical research had linked the two. By identifying the cause-and-effect mechanism that links the two, the research team has solved three persistent mysteries associated with autism.
Vitamin D activates a gene that controls two enzymes:
- Tryptophan hydroxylase 2 (TPHS), which transforms the enzyme into serotonin in the brain. In the brain, serotonin shapes brain structure and neural circuitry, acts as a neurotransmitter, and influences social behavior.
- Tryptophan hydroxylase 1 (TPH1), transforms the enzyme into serotonin in the digestive tract, where too much of it induces inflammation. Vitamin D stops production of TPH1, thereby lowering inflammation.
Awareness of this interaction brings new understanding to three facts associated with autism:
- The “serotonin anomaly”: Too little serotonin in the brain but high levels in the bloodstream of autistic patients.
- Why more boys than girls are autistic: Estrogen, more abundant in girls, produces the same serotonin-stimulating effect in the brain as vitamin D does.
- Why the immune systems of mothers of autistic children produce autoimmune antibodies to the fetal brain: When vitamin D restricts production of TPH1, it also restricts production of T-cells that regulate the immune system.
When bare skin comes in contact with sunlight, vitamin D is produced. Sunscreen and the pigment, melanin, filter the sunlight’s UVB rays, making vitamin D production inadequate. The darker a person’s skin — naturally or by tanning — the more melanin it produces. People with dark skin who live in northern locales are often deficient in vitamin D unless they take supplements.
A recent survey conducted by the National Health and Examination board reveals vitamin D deficiency in more than 70% of the US population. Furthermore, as vitamin D deficiency has become more common in the general population over the last two decades, the number of autism diagnoses has risen accordingly.
The CHORI research team suggests dietary supplements of vitamin D, tryptophan, and omega-3 fatty acids could boost serotonin levels enough to ease ASD symptoms without undesirable side effects. The team would also like to see testing for vitamin D levels to become a standard part of prenatal care.
Source: “Research by CHORI Scientists Indicates Causal Link between Vitamin D, Serotonin Synthesis and Autism: Dietary Interventions Will Have Relevance for Prevention and possibly for Treatment of Autism.” Children’s Hospital & Research Center Oakland. Children’s Hospital & Research Center Oakland. Feb 26, 2014. Web. Mar 14, 2014.