Vitamin D Supplementation on 15-Prostaglandin Dehydrogenase Expression in Barrett’s Esophagus

Inclusion Criteria:

Known diagnosis of short-segment or long-segment Barrett's esophagus as previously made by upper endoscopy showing salmon-colored distal esophageal mucosa and biopsies revealing intestinal metaplasia with goblet cells. Potential study subjects may be contacted by mailings or phone calls or may be approached in clinic. Additionally, potential study subjects may be approached using a web-based recruitment tool. Informed consent will be obtained by a research coordinator or study investigator.
Subjects may be taking calcium supplements or have previous history of hypercalcemia
Subjects may have diabetes mellitus
Subjects may have a history of prior malignancy except for esophageal adenocarcinoma
Willing to donate 90 mL of blood and endoscopic mucosal biopsies for research

The following additional inclusion criteria apply for patients in the Vitamin D/metformin sub-arm of the low grade dysplasia/no dysplasia arm:

At least 2 cm circumferential Barrett's esophagus segment length (C2M2 by Prague C & M criteria)
Normal renal function (defined as creatinine within normal institutional limits)

Exclusion Criteria:

Pregnancy
Known chronic liver disease (Child's B cirrhosis)
Known chronic kidney disease (creatinine ≥ 3.0)
Esophageal adenocarcinoma
Allergic reaction to omeprazole
Allergic reaction to vitamin D
Unable or unwilling to provide informed consent
Known hypercalcemia
Previous ablative therapy for Barrett's esophagus
Patients on a stable (>/=4 week duration) dose of >2000 IU/day (or equivalent) of vitamin D supplementation

The following additional exclusion criteria apply for patients in the Vitamin D/metformin sub-arm of the no dysplasia/low grade dysplasia arm:

Allergic reaction to metformin
History of diabetes mellitus
History of lactic acidosis
History of B12 deficiency
Participants may not be using metformin, cimetidine (Tagamet) furosemide (Lasix), nifedipine (Cardizem), or any other drug contraindicated for use with metformin.
Treatment with other oral hypoglycemic agents
Participants planning to undergo elective radiologic studies involving intravascular administration of iodinated contrast materials.
Known chronic kidney disease with creatinine greater than normal institutional limits