The study in the Journal of Allergy and Clinical Immunology followed more than 1,000 children with asthma for four years. It found vitamin D insufficiency itself was linked to a 50 percent increase in the risk of severe asthma attacks.
But, at the same time, researchers found no evidence that vitamin D levels protected kids from moderate asthma symptoms.
Scientists say it's possible vitamin D's effect on the immune systems inflammatory response may be playing a role.
