Got vitamin D? Study finds low levels in critically ill children

by Tom Ulrich on August 16, 2012

The sun helps us get some of the vitamin D we need, but not enough of it. A new study finds that critically ill kids are more than twice as likely as kids generally to be vitamin D deficient. (nichole ★/Flickr)

When a child is admitted to a hospital’s intensive care unit (ICU), probably one of the last things on anyone’s mind is, “Are they getting enough vitamin D?”

But this question could be a very important one, according to Kate Madden, MD, and Adrienne Randolph, MD, critical care medicine specialists at Boston Children’s Hospital. In a study of children admitted to Boston Children’s ICU, they found that those with very low vitamin D levels—below what the American Association of Pediatrics (AAP) considers deficient—tended to have more severe illness.

So what’s so important about vitamin D? Turns out, a lot more than most people think.

“Vitamin D is actually a hormone, and is thought to have a myriad of effects on the body,” Randolph says. Included are the long-recognized benefits for bone health, such as prevention of rickets (a condition in which bones become soft and weak); a recent study also recently linked low vitamin D levels and the risk of stress fractures among female athletes. And for some time, researchers have accumulated a growing body of evidence that vitamin D promotes cardiovascular health and immune function.

“The exact roles played by vitamin D outside the bones remain somewhat controversial,” says Susanna Huh, MD, MPH, director of Boston Children’s Growth and Nutrition Program. “But it may help immune system development and function, and among adults it may help reduce the risks of hypertension, coronary artery disease, diabetes and cancer.”

With Randolph’s study, the evidence for vitamin D’s role in general health should be a bit stronger. Her team measured the vitamin D levels of more than 500 children in Boston Children’s ICU over a one-year period, comparing this information to how sick each child was.

One thing immediately jumped out: just over 40 percent of children in the ICU had vitamin D deficiency (defined as levels below 20 ng/ml of blood)—a rate more than two and a half times that in the general U.S. child population.

Next was the relationship between vitamin D levels and the severity of a child’s illness. The sicker the child—as scored with a standard ICU evaluation score tool called PRISM III—the more likely he or she was to have a vitamin D deficiency.

“It’s been known for some time that adults in intensive care who are vitamin D deficient tend to be worse off,” Randolph notes. “This is the first time the relationship between severity and deficiency has been documented in children in the ICU.”

Randolph’s team also looked at risk factors for deficiency, finding that a higher risk among:

  • School age children and adolescents
  • Children with darker skin
  • Those who were not taking vitamin D supplements or multivitamins with vitamin D
  • Those admitted to the hospital in the colder months

This cow wants to know whether you've gotten enough vitamin D today. (Cathy, Sam, Max and Mai/Flickr)

Huh noted that these factors line up with most of the general risk factors for vitamin D deficiency.

Randolph’s take away message from the study? “At least in the critical care setting, doctors should proactively screen children at risk for vitamin D deficiency, and give supplements should they find that a child has low levels.”

But as a general rule, how can kids get more vitamin D? After all, our bodies naturally produce vitamin D when we’re exposed to sunlight, right?

“Because of the risk of skin cancer, unprotected exposure to sunlight is not recommended as a way of producing vitamin D, and it’s difficult to get enough vitamin D from the diet because few foods contain vitamin D,” Huh cautions. “The AAP has recommended that all children and teenagers consume at least 400 IU of vitamin D daily, and the Institute of Medicine has recommended 600 IU daily for children and teenagers.

“Although foods such as fortified milk, eggs and fatty fishes such as salmon can provide some vitamin D,” Huh continues, “many children will need a daily vitamin D supplement to meet the recommended intake.”

So do what you can to get more vitamin D. More importantly, make sure your kids do.

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