Vitamin D and Microbiota in Cystic Fibrosis

Monocentric, double-blind, randomized, placebo-controlled, interventional pilot study to
investigate the beneficial effects of high dose vitamin D supplementation on gut and lung
microbiota in patients with cystic fibrosis who are vitamin D insufficient.

Inclusion Criteria:

- Presenting to the Cystic fibrosis clinic for routine follow up of cystic fibrosis

- Serum 25(OH)D concentrations obtained within 2 months of enrollment

- Able to tolerate oral medications

Exclusion Criteria:

- Inability to obtain or declined informed consent from the subject and/or legally
authorized representative

- Pregnancy or plans to become pregnant in the next 3 months

- History of disorders associated with hypercalcemia including parathyroid disease

- Current hypercalcemia (albumin-corrected serum calcium >10.8 mg/dL or ionized calcium
>5.2 mg/dL)

- History of nephrolithiasis with active symptoms within the past two years

- Chronic kidney disease worse than stage III (<60 ml/min)

- Current significant hepatic dysfunction total bilirubin > 2.5 mg/dL with direct
bilirubin > 1.0 mg/dL

- Current use of cytotoxic or immunosuppressive drugs

- History of AIDS

- History of illicit drug abuse (defined as history of enrollment into a drug
rehabilitation program or hospital visits due to drug use within the past 3 years or
any use of the following drugs in the past 6 months (cocaine, opiates, amphetamines,
marijuana) or any positive toxicology screen for (cocaine, opiates, amphetamines,
marijuana)

- Too ill to participate in study based on investigator's or study team's opinion

- Current enrollment in another intervention trial