A new study published in the journal Dermato-Endocrinology found that vitamin D can help lower the risk of developing autism.
The researchers studied the prevalence — the proportion of a population found to have a condition — of autism in children ages 6 to 17 on a state-by-state basis. The evidence showed that states that have higher amounts of UVB in the summer or fall had half the autism rate of states with lower UVB amounts.
In states that had lower amounts of UVB, blacks had a 40 percent higher autism rate than whites. This is because African Americans have darker skin because they have more melanin, the pigment that gives skin its color. Since UVB is the primary source of vitamin D for most Americans,and since skin pigmentation is a major photoprotective factor, UVB rays do not penetrate darker skin as much as they do lighter skin.
The study raised questions about whether autism is caused by a mother’s lack of vitamin D during pregnancy, a lack of a vitamin D in the individual, or both.
Previous studies have also made the connection between vitamin D deficiency and autism in children. In A Swedish study published in Developmental Medicine and Child Neurology, researchers found the prevalence of autism and other disorders was three to four times higher among Somali immigrants than non-Somalis living in Stockholm.
Elisabeth Fernell, a researcher at the Karolinska Institute in Sweden’s capital and a co-author of the study, said Stockholm’s Somali population calls autism “the Swedish disease.”
As with black Americans in states with lower amounts of UVB, Somalis in Sweden were getting less sun — and less vitamin D — than in their native country. During the summer, those with fairer skin produce around 1,000 IUs of vitamin D per minute, but those with darker skin synthesize vitamin D more slowly.
Vitamin D may help lower the risk of autism by strengthening the body’s immune system during early life, which makes it important that a mother be vitamin D sufficient during her pregnancy. Adit Ginde, an assistant professor at University of Colorado Denver School of Medicine recommended getting 1,000 to 2,000 IUs of vitamin D per day.