A new study adds to the growing body of evidence that vitamin D helps lower the risk for the development of autism.
For the study, researchers looked at the prevalence of autism in children ages 6-17 according to the state in which they lived. They discovered that states with higher solar ultraviolet-B (UVB) in summer or autumn had half the rate of autism as states with the lowest amounts.
In states with the least solar UVB, black Americans had a 40% higher rate of autism than white Americans. Black Americans have lower vitamin D concentrations due to their darker skin and since solar UVB is the main source of vitamin D for most Americans.
This finding leads to the question of whether the disorder is due to the mother’s vitamin D deficiency during pregnancy or a vitamin D deficiency in early life or both.
Other studies have shown negative effects on fetal brain development during the third trimester of pregnancy related to vitamin D deficiency, including increased risk of schizophrenia and language problems. Also, a higher risk of autism in springtime births has been reported in several studies.
One of the ways in which vitamin D might reduce the risk of autism during pregnancy is by lowering 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. Vitamin D also reduces inflammation.
In early life, vitamin D might reduce the risk of autism by strengthening the body’s immune system and reducing inflammation.
Several other recent studies have shown that vitamin D deficiency is common among autistic children. Once the disorder has developed, symptoms may be reduced by treating the deficiency in autistic children, although this remains to be shown in randomized controlled trials.
The study is published online in the peer-reviewed journal Dermato-Endocrinology.