The American Academy of Pediatrics is doubling its recommendation on the amount of vitamin D kids should get each day, noting new research that suggests it may help prevent serious diseases. Most kids would have to take supplements to get the 400 units the organization now advises.

The best source of Vitamin D is sunlight, as this story about the change in recommendation points out, but we've all been slathering sunscreen on our kids to avoid skin cancer (which we still need to avoid). And kids who are breast-fed (which many pediatricians recommend for the first year of life) probably get less vitamin D than formula-fed babies, though they reap other benefits.