Autism: vitamin D helps improve behavior
Autism and vitamin D: here's what links them and how it improves behavior
Vitamin D may influence serotonin levels in the brain and modify abnormal behaviors in children with autism. More precisely, it appears that adequate levels of the vitamin are needed to stimulate the production of this important hormone that regulates function, brain structure, and social behavior.
This is the finding of a study published in The FASEB Journal, and conducted at the Children's Hospital Oakland Research Institute in California, USA, with the aim of revealing the link between serotonin, vitamin D and autism disorder.
Autism, serotonin, and vitamin D
Serotonin, also known as the "feel-good hormone," is a neurotransmitter produced in the brain, and other tissues, from the amino acid tryptophan. Several studies in recent years have identified a relationship between serotonin deficiency and autism, a neuropsychiatric disorder characterized by repetitive and stereotyped behaviors and impaired communication and social relationships. Previous research has identified a link between autism and deficiency of vitamin D, a molecule known primarily for its ability to regulate the absorption and deposition of calcium and phosphorus. The mechanism linking vitamin D, serotonin and the symptoms of autism had not been highlighted until now.
The findings of the new study
Researchers found that vitamin D is able to activate the gene that produces the enzyme TPH2 (tryptophan hydroxylase 2), which is needed to convert the amino acid tryptophan into serotonin, in the central nervous system. In contrast, the vitamin is able to deactivate the gene for the enzyme TPH1, which, like TPH2, produces serotonin in the gut and other tissues where, if in excess, it promotes inflammation.
The opposite effect of vitamin D on the two genes would explain some conditions typical of autism, including elevated serotonin concentration in the blood compared with the nervous system and the resulting deficits in brain development. Low levels of the vitamin during fetal and neonatal development could cause insufficient TPH2 activity with serious consequences for the brain both structurally and functionally.
This hypothesis suggests the importance of adequate vitamin D intake during pregnancy, as well as vitamin D and tryptophan in early childhood. The researchers found that oxytocin and vasopressin, two other brain hormones that affect social behavior, are also stimulated by the presence of vitamin D.
Vitamin D to improve symptoms of autism
Although more studies are needed, the researchers speculate that supplementation with vitamin D, along with Omega-3 and tryptophan, could help prevent or improve some of the behaviors typical of autism, without the risk of side effects.
In this regard, they also pointed out that the vitamin D levels recommended by the guidelines, refer to the concentrations needed to ensure proper bone health (30 ng/mL), while they may not be sufficient to ensure other functions in other tissues such as the nervous tissue.
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Source: Rhonda P. Patrick and Bruce N. Ames "Vitamin D hormone regulates serotonin synthesis. Part 1: relevance for autism" The FASEB Journal, 2014; DOI: 10.1096/fj.13-246546.
