Thursday, June 18, 2009

Vitamin D deficiency soars in the U.S., study says: Scientific American

Vitamin D deficiency soars in the U.S., study says: Scientific American

Three-quarters of U.S. teens and adults are deficient in vitamin D, the so-called "sunshine vitamin" whose deficits are increasingly blamed for everything from cancer and heart disease to diabetes, according to new research.

The trend marks a dramatic increase in the amount of vitamin D deficiency in the U.S., according to findings set to be published tomorrow in the Archives of Internal Medicine. Between 1988 and 1994, 45 percent of 18,883 people (who were examined as part of the federal government's National Health and Nutrition Examination Survey) had 30 nanograms per milliliter or more of vitamin D, the blood level a growing number of doctors consider sufficient for overall health; a decade later, just 23 percent of 13,369 of those surveyed had at least that amount.

The slide was particularly striking among African Americans: just 3 percent of 3,149 blacks sampled in 2004 were found to have the recommended levels compared with 12 percent of 5,362 sampled two decades ago.

"We were anticipating that there would be some decline in overall vitamin D levels, but the magnitude of the decline in a relatively short time period was surprising," says study co-author Adit Ginde, an assistant professor at the University of Colorado Denver School of Medicine. Lack of vitamin D is linked to rickets (soft, weak bones) in children and thinning bones in the elderly, but scientists also believe it may play a role in heart disease, diabetes and cancer.

"We're just starting to scratch the surface of what the health effects of vitamin D are," Ginde tells ScientificAmerican.com. "There's reason to pay attention for sure."

What If Vitamin D Deficiency Is a Cause of Autism?: Scientific American

What If Vitamin D Deficiency Is a Cause of Autism?: Scientific American

As evidence of widespread vitamin D deficiency grows, some scientists are wondering whether the sunshine vitamin—once only considered important in bone health—may actually play a role in one of neurology's most vexing conditions: autism.

The idea, although not yet tested or widely held, comes out of preliminary studies in Sweden and Minnesota. Last summer, Swedish researchers published a study in Developmental Medicine and Child Neurology that found the prevalence of autism and related disorders was three to four times higher among Somali immigrants than non-Somalis in Stockholm.

[...]

What seemed to link the two regions was the fact that Somalis were getting less sun than in their native country—and therefore less vitamin D. The vitamin is made by the skin during sun exposure, or ingested in a small number of foods. At northern latitudes in the summertime, light-skinned people produce about 1,000 international units (IUs) of vitamin D per minute, but those with darker skin synthesize it more slowly, says Adit Ginde, an assistant professor at the University of Colorado Denver School of Medicine. Ginde recommends between 1,000 to 2,000 IUs per day, calling current recommendations of 200 IUs per day outmoded.