Vitamin D Oral Replacement in Asthma

Inclusion Criteria: * Body mass index greater than or equal to 85% for age and sex * Physician-diagnosed asthma * Ongoing relationship with asthma provider responsible for asthma care * Serum 25(OH) D level 10 ng/ml to less than 30 ng/ml at screening visit based on local laboratory test * Ability to swallow pills similar in size to the vitamin D preparation to be used * Signed consent form from parent, legal guardian or caregiver and signed assent from participant (as appropriate) * Females of childbearing years must not be pregnant, must not be lactating and must agree to practice adequate birth control method * Child and parent, legal guardian, or caregiver must speak English or Spanish Exclusion Criteria: * Known diseases of calcium metabolism or the parathyroid * History of renal insufficiency or kidney stones * Known liver failure or history of abnormal liver function tests * History of Williams syndrome, sarcoidosis, or granulomatous disease * Active tuberculosis * Spot urine calcium/creatinine ration greater than 0.37 (calcium and creatinine measured in mg/ml). This can be repeated following adequate hydration * Clinical evidence of rickets * Taking supplemental vitamin D greater than equal to 1000 IU per day