Vitamin D for Enhancing the Immune System in Cystic Fibrosis (DISC Study)

Patients with Cystic Fibrosis (CF) have a shorter life span than the general population due to complications with lung infections, which eventually progress to lung failure. New research has suggested that high levels of vitamin D may be protective against lung infections and may promote the action of anti-bacterial proteins needed to ward off infections. Research has also suggested that high vitamin D levels are linked to lower mortality rates; however these hypotheses have not been adequately studied in patients with CF. An investigation of the effects of vitamin D supplementation is of particular interest in this population because patients with CF generally have high rates of vitamin D deficiency. The investigators have preliminary data from a previous study suggesting that vitamin D supplementation in patients with CF lowers markers of inflammation, promotes anti-bacterial proteins, and reduces mortality. In this proposed multi-center study the investigators will examine the effects of a high dose vitamin D supplementation on patients with CF who are admitted to the hospital for lung infection. The investigators will use a randomized, placebo-controlled trial design to determine if mortality and infection rates over 1 year are reduced in patients who receive the high-dose vitamin D supplementation compared to those who receive placebo. The investigators will also determine if vitamin D affects markers of inflammation and anti-bacterial proteins, as well as CF-related clinical outcomes, such as lung function. The investigators plan to recruit 280 adults and adolescents with CF (ages \> 16yrs), with approximately 150 subjects recruited at Emory (Emory University Hospital and Children's Healthcare of Atlanta). Participants will initially be seen by the study researchers during the first week of in-patient hospitalization, and they will be followed over the course of one year during their regularly-scheduled out-patient CF clinic visits. The treatment group will receive an initial oral bolus dose of 250,000 IU vitamin D, and at 3 months follow-up they will receive 50,000 IU vitamin D every other week. Current CF Guidelines for vitamin D supplementation recommend a daily intake of 800 IU of vitamin D per day, therefore in addition to the vitamin D or placebo they receive at the beginning of the study and at 3 months, all participants will receive 800 IU of vitamin D daily. If our hypotheses are correct, this study has potential for reducing infection and promoting survival in patients with CF using vitamin D, a relatively inexpensive supplement.