Each patient who is admitted for preoperative preparation for elective open heart surgery at Intermountain Medical Center will be invited to participate in this study. After a written informed consent is obtained, patients meeting inclusion/exclusion criteria will be randomized 1:1 to the treatment arm or placebo/control arm. Those randomized to the treatment arm will receive three 50,000 unit oral doses of vitamin D3 supplementation. The first dose will be given the evening before surgery. The second and third doses will be given either orally or per NG tube on the mornings of post-op days 1 and 2. Blood will be obtained at the following time periods: 1) At baseline pre-procedure 12 to 18 hours before planned surgery; 2) Post-operative day 1, 12 to 24 hours after surgery; 3) 48 hours after surgery; 4) 72 hours after surgery; 5) At discharge (estimated to be between 5-8 days after surgery); and 6) At the 6-month follow-up visit (post-surgery). Plasma levels of 25(OH) vitamin D will be measured on each sample.

Each patient who is admitted for preoperative preparation for elective open heart surgery at Intermountain Medical Center will be invited to participate in this study. The patient's history and medical records will be reviewed and data gathered will be used to evaluate the patient's relationship to inclusion and exclusion criteria. After a written informed consent is obtained, subjects will be randomized 1:1 to the treatment arm or placebo/control arm. Those randomized to the treatment arm will receive three 50,000 unit oral doses of vitamin D3 supplementation. The first dose will be given the evening before surgery. The second and third doses will be given either orally or per NG tube on the mornings of post-op days 1 and 2. Approximately 15-20 ml (about one tablespoon) of blood will be obtained at the following time periods (+/- 4 hours): 1) At baseline pre-procedure 12 to 18 hours before planned surgery; 2) Post-operative day 1, 12 to 24 hours after surgery; 3) 48 hours after surgery; 4) 72 hours after surgery; 5) At discharge (estimated to be between 5-8 days after surgery); and 6) At the 6-month follow-up visit (post-surgery). Each blood sample will be transported to The Center for Molecular and Genetic Research at LDS Hospital Cardiovascular Genetics Laboratory for preparation and storage. Plasma levels of 25(OH) vitamin D will be measured on each sample.

Inclusion Criteria:

1. Male or female >= 18 years of age
2. Ability to understand and sign a written informed consent form, which must be obtained prior to initiation of any study procedures
3. Subject is scheduled for elective open heart surgery at Intermountain Medical Center
4. Subject is relatively stable as assessed by the Principal Investigator

Exclusion Criteria:

1. Inability or refusal of the patient and/or the patient's legally acceptable representative to provide written informed consent for any reason.
2. History of previous vitamin D supplementation > 1,000 units of vitamin D3 per day within the past three months.
3. Evidence of hypercalcemia on screening labs (> 10.5 milligrams per deciliter of blood).
4. Any scheduled cardiac surgical procedure that does not require open thoracotomy (the reason for this exclusion is that the study design requires that the patients will undergo a significantly stressful procedure, which can be generally guaranteed if the patient undergoes open thoracotomy).
5. Known allergic reaction or other intolerance to oral vitamin D3.
6. Pregnant and/or lactating women and women of child bearing potential who are not using acceptable means of contraception. Women of childbearing potential must be using adequate measures of contraception (as determined by the Principal Investigator) to avoid pregnancy and should be highly unlikely to conceive during the study period. Women of childbearing potential must have a negative pregnancy test at screen.
7. Subject participation in previous investigational interventional studies within 30 days of the current study.
8. Other conditions that in the opinion of the Principal Investigator may increase risk to the subject and/or compromise the quality of the clinical trial.