The Supplement Question
But there is one big difference between the D your body produces in response to sunlight and the kind that comes from a bottle. Sun-activated D lasts twice as long in your body, which is why you only need sun exposure a few days a week, notes Dr. Holick. If you or your child avoid the sun and don't drink enough milk or eat lots of D-rich foods, a daily supplement or a multivitamin can help you meet AAP and IOM guidelines. (The D3 form is more effective at raising blood levels than D2.) Both pregnant and nursing women need a prenatal vitamin containing 400 IU of D per day.
Anyone who's found to have low D levels will be given supplements. Erin Danner's treatment consisted of two over-the-counter D-fortified calcium chews a day -- a total of 1,000 IU of D -- and more milk. Within four months, her levels had risen from 20.3 to 34.8. "Erin was doing cartwheels at summer camp and hasn't complained about pain for months," says her dad. Still, her doctor wants her to continue taking the calcium chews to boost her D levels above 40 and keep them there.
Depending on whom you talk to, vitamin D is either the best thing since sliced bread -- or a story that's still unfolding. The ideal amount is still the great unknown. The government says that the safe upper limit for D is 1,000 IU for babies younger than 1, and 2,000 IU for everyone else, but some experts maintain that higher doses are fine. In fact, the Vitamin D Council, a nonprofit that educates people about D deficiency, advises that everyone over age 1 take 1,000 IU for every 25 pounds they weigh. "With most adults, 5,000 IU per day is adequate to maintain optimal D levels," says John Cannell, M.D., president of the council.
Many experts think it's best to wait for more studies before jumping on the vitamin-D bandwagon. "While it makes sense to keep D levels in the normal range, we need clinical trials before we make public health recommendations that everyone take a D supplement," says Judith Wylie-Rosett, Ed.D., R.D., a spokesperson for the American Heart Association.
Dr. Gordon is among those who are firm believers in its potential. "More studies are coming to the same conclusions about D's promising effects throughout the body. This is very exciting and something we must pay attention to," she says. "But we need more research about D's risks and benefits, especially when it comes to children. Hopefully, that day won't be too far off."