The long term goal in our research is to develop and implement effective, evidence-and mechanism-based interventions to improve outcomes for surgical and trauma patients. Of potential importance, findings from our own recent pilot studies have established that > 95% of patients seen at Truman Medical Center (TMC) are seriously Vitamin D deficient with plasma levels significantly lower than normal. Our objective in this application, therefore, is to assess the short term therapeutic benefit of high dose Vitamin D in patients admitted to TMC for elective major abdominal surgery. We propose to measure plasma Vitamin D and Calcium levels before supplementation (pre-operatively), and after supplementation (post-operatively), and monitor the biomarker proteins cathelicidin and resistin at the same times. Data on Vitamin D levels will be used to assess direct biochemical effects. Measurement of cathelicidin levels will provide additional information. Since Vitamin D has been shown to induce increased expression of this antimicrobial protein. Monitoring of circulating levels of resistin provides a highly sensitive early measure of infection (unpublished observations). Calcium levels will also be monitored since there is a significant chance that pre-operative calcium levels will be low in some patients, and that supplementation with vitamin D may increase the calcium level.