The D Challenge
To achieve sufficient D levels, the Institute of Medicine (IOM) advises that everyone get 200 IU of D per day until age 50. In 2008 the AAP doubled its D recommendations for children from 200 to 400 IU daily, which is the equivalent of a quart of D-fortified milk or formula. (The IOM was expected to increase its recommendations on November 30, after this story went to press.) Since breast milk doesn't contain D -- and babies shouldn't drink cow's milk until age 1 -- the AAP advises that partially or exclusively breastfed infants receive a supplement of 400 IU of liquid D every day. "This is enough to keep your child from being D deficient," says Dr. Greer, who coauthored the academy's statements on D.
More doctors are now testing their patients' vitamin D levels. For the last quarter of 2009, tests surged by more than 50 percent compared with that period in 2008, reports Quest Diagnostics, the nation's largest medical laboratory company. "I'm seeing a lot of kids with chronic fatigue and muscle aches, so I'm checking D levels and often finding very low ones," says pediatrician Kathi J. Kemper, M.D., chair for holistic and integrative medicine at Wake Forest University School of Medicine, in Winston-Salem, North Carolina.
Why do so many of us earn an F when it comes to D? It's simply not found in many food sources, for one thing (see "Where the D Is" on page 7 for options). But being overweight is also a factor. Because D is fat soluble, it gets stored in fat tissue, so less of it remains in the bloodstream. "Most obese adults need two to three times more D than normal-weight people to satisfy their requirement," says Dr. Holick. It's not clear whether this is also the case with children, because studies haven't been done on them.