The summer sun is almost upon us, which means my kids will be getting no vitamin D whatsoever, because I’m going to slather sunscreen on them like cream cheese on bagels. Considering that my son doesn’t like milk and my daughter spills more than she drinks, I’ve wondered just how much vitamin D they get and whether it’s enough.
Turns out a lot of parents should be concerned about this. Many American kids are not getting enough vitamin D, which could be damaging their bones or worse. A 2009 study published in the journal Pediatrics analyzed data from the U.S. National Health and Nutrition Examination Survey and found that nearly 1 out of 5 American kids aged 1 to 11 have blood levels of vitamin D below the 50 nanomols per liter (nmol/L) recommended by the American Academy of Pediatrics. That is a pretty conservative benchmark: The Canadian Paediatric Society recommends that kids maintain a higher vitamin D blood level of 75 nmol/L—yet a whopping 69 percent of U.S. kids do not meet this guideline. A 2012 study reported similar numbers among healthy-weight kids and found that obese kids were even more likely to be vitamin D deficient. (Darker skinned kids, whose bodies don’t make vitamin D as efficiently from sunlight, as well as obese kids tend to be most at risk.)
So is the solution to give kids vitamin D supplements? How do you know if your wee ones are getting enough or too much—and why does vitamin D matter, anyway?
Let’s start with some science, because vitamin D is controversial. It’s not that doctors disagree over whether it’s important—it’s that they disagree over how many things it’s important for and how much people need. Everyone acknowledges that vitamin D boosts calcium absorption in the gut and builds strong…