A new study has linked both more asthma symptoms and greater use of steroid medication to low levels of vitamin D in children.

Researchers at the National Jewish Medical and Research Center in Denver say 47 percent of their asthma patients have "insufficient" vitamin D levels, and an additional 17 percent have "deficient" levels, which is comparable with vitamin D levels found in the general population. Asthmatic children with low vitamin D levels have higher levels of IgE, an allergy marker, according to the paper.

On the other hand, supplementation with Vitamin D "may help reverse steroid resistance in asthmatic children and reduce the effective dose of steroids needed," says study researcher Daniel Searing, MD.

The “sunshine vitamin” correlates to bone health, immunity, lower risk of heart disease, and cancer-risk reduction. It also may help relieve growing pains.

To boost D, have kids get at least 15 minutes of sunshine daily, sans sunscreen. Newborns and children up to 5 years old can take ½ to 1 teaspoon daily of cod-liver oil, the richest food source. Or supplement with D3 (cholecalciferol), the most absorbable form. The American Academy of Pediatrics (AAP) recently doubled the amount of vitamin D it recommends for kids to 400 IU, but many experts say it's safe for kids to take 800 IU or more.