Too much television and too little milk means that black children are not getting enough of vitamin D, a new study says. Known as the “sunshine vitamin” because it can also be obtained through sun exposure, Vitamin D can stave off rickets, improve bone health, and possibly prevent colds, heart disease and diabetes.  

In the 1930s, when the U.S. started putting Vitamin D into milk, rickets—a softening of bones that can lead to deformities—was thought to have been eradicated. But doctors around the country recently have started seeing a spate of cases in African-American and Muslim communities. “We wanted to see how big a problem Vitamin D deficiency is,” says Michal Melamed of the Albert Einstein College of Medicine.  

Using data from the National Health and Nutrition Examination Survey of 2001 to 2004, Melamed and colleagues looked at the prevalence of Vitamin D deficiency (defined as less than 15 nanograms per milliliter of blood) in 6,275 children and teenagers. The researchers compared non-Hispanic blacks, non-Hispanic whites and Mexican Americans by sex and age class.

The highest risk groups were blacks followed by Mexican Americans and then whites. Within these groups, teenage girls, age 13 to 21, fared the worst. Among blacks, 59 percent of teenage girls were found to be Vitamin D deficient, whereas just 5 percent of white teenage girls were deficient.

That's not to say boys don't have to worry. Among blacks, 43 percent of teenage boys were at risk. Overall, one in 10 U.S. children, regardless of race, are deficient in Vitamin D. The study was published today in Pediatrics.

“What we think is that sunscreen use has gone up and milk intake has gone down,” Melamed said. Indeed, the number of Americans who rarely drink milk has gone up from 22 percent in the early 1990s to 28 percent in the early 2000s. “Kids are also spending a lot more time indoors watching TV and playing video games than they have in the past,” she said, adding, “We found that kids who watch TV more than four hours per day were 60 percent more likely to have a Vitamin D deficiency.”  

Fair-skinned children can get their daily dose of Vitamin D with just 10 to 20 minutes in the sun prior to applying sunscreen. But sun-protective skin pigments in black children means that they need to be outdoors up to an hour per day. Blacks are also more likely to have lactose intolerance, restricting their intake of dairy.   

The American Academy of Pediatrics also recommends that infants, children and teens take up to 400 IU of Vitamin D per day.  

“You have to tailor things to your skin type,” says Melamed, “Obviously, if your family has a history of melanoma [skin cancer], get little sun and take supplements.”

Image of girl in sun courtesy ale i via Flickr