12 January - 20 June 2016

Causal link established between vitamin D and autism

12 Mar 14

Vitamin D is currently enjoying the public health spotlight. It is estimated that a high percentage of individuals - especially in northern latitude countries - are vitamin D deficient, resulting in an increase of rickets cases in the UK particularly. Vitamin D deficiency has also been implicated in other diseases such as hypertension, diabetes and cancer, and new research now suggests a link to autism.

Researchers from the Children's Hospital Oakland Research Institute, Drs Rhonda Patrick and Bruce Ames, have discovered that vitamin D activates the hormones serotonin, oxytocin and vasopressin (all hormones associated with autism). The proposed mechanism involves calcitriol, the biologically active form of vitamin D formed in the human body. Vitamin D that is ingested from foods or supplements or formed in the skin by UV light exposure is converted to calcitriol. Low levels of serotonin (a neurotransmitter) have been noted in the brains of autistic children compared with higher levels in their blood. Sufficient vitamin D levels will increase calcitriol, which will activate the gene for the enzyme tryptophan hydroxylase 2(TPH2). TPH2 then converts the essential amino acid tryptophan to serotonin in the brain. Calcitriol also inhibits the activity of tryptophan hydroxylase 1(TPH1) which synthesises serotonin in the gut (where excess can cause inflammation) and other tissues. The dietary interventions suggested by the researchers are therefore supplementation with vitamin D and tryptophan.

The same mechanism occurs for the hormones oxytocin and vasopressin. Oxytocin is involved in strengthening social behaviours such as maternal care and bonding, and vasopressin in social recognition, anxiety, etc. Calcitriol acts by modulating the synthesis of oxytocin as well the tissue(s) response to it and also modulates the gene expression for vasopressin. [ScienceDaily], [Eurekalert]

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