Researchers have found additional evidence that vitamin D reduces the risk of developing autism by half.
The study examined the variation of autism prevalence by state in the US for those aged 6-17 years in 2010. It found that states with higher solar ultraviolet-B (UVB) doses in summer or autumn had half the rate of autism as states with the lowest.
Similar geographical variations have been noted for incidence and mortality rates for 15 types of cancer in the US.
One of the mechanisms whereby vitamin D might reduce autism risk is through reducing the risk of sporadic DNA mutations from influencing fetal development.
Another is through reducing the risk of influenza and other infectious diseases during pregnancy, which have been linked to increased risk of schizophrenia. Also, vitamin D reduces inflammation by shifting cytokine production towards less inflammatory cytokines.