Researchers at the University of Illinois at Chicago are recruiting volunteers with asthma for a study of whether taking vitamin D can make asthma medication more effective.

The study is called VIDA (Vitamin D add-on therapy enhances corticosteroid responsiveness in Asthma).

"A number of people with asthma have low vitamin D levels," says Dr. Jerry Krishnan, professor of medicine, pulmonary, critical care, sleep, and allergy. "Patients with asthma and low vitamin D levels tend to have worse lung function, and tend to have more asthma attacks."

The researchers are looking for participants who are 18 years or older and are using medications to control their asthma. Volunteers whose baseline vitamin D levels are low and whose asthma is not well controlled may enroll in the study.

Study participants will receive vitamin D or a placebo and will continue on asthma medications. They will monitor their lung function at home as well as having regular clinic visits over the course of nine months. Participants will be compensated for their time.

"We want to understand if taking vitamin D allows their asthma to get better," Krishnan said.

The researchers hope that for people with low levels of vitamin D, supplements of the vitamin will make it possible to use less asthma medication.

"Improving your asthma control may be as simple as taking a vitamin a day," Krishnan said.

Taking vitamin D may result in side effects, so Krishnan warned against taking vitamin D for asthma outside of a study. In the study, researchers carefully monitor patients to detect potential side effects, Krishnan said.

Krishnan urged anyone interested in learning whether low vitamin D is the reason their asthma does not get better to consider enrolling in the study.