| Exclusion Criteria: | 1) Current participation in another colorectal (bowel) study
2) Current participation in any other clinical trial (intervention study)
3) Previous participation in another colorectal chemoprevention study
4) Pregnancy or lactation
5) Diagnosed narcotic or alcohol dependence
6) Dementia (e.g. Alzheimer's)
7) Significant psychiatric disability (e.g. Schizophrenia, refractory bipolar disorder, current severe depression)
8) A history of kidney stones
9) A history of granulomatous diseases: sarcoidosis (within 10 years), active chronic fungal or mycobacterial infections (tuberculosis, histoplasmosis, coccidioidomycosis, blastomycosis), Berylliosis, Wegener's granulomatosis
10) A history of hyperparathyroidism
11) Severe renal disease: chronic renal failure
12) A history of unexplained hypercalcemia
13) Diagnosed osteoporosis or physician recommendation for treatment of low bone mass
14) Two or more low trauma fractures
15) Medical condition requiring treatment with vitamin D (e.g. osteomalacia)
16) History of invasive carcinoma of the large bowel (even if confined to a polyp)
17) Familial colorectal cancer syndromes: Adenomatous Polyposis, HNPCC, Hamartomatous Polyposis syndromes, Noninherited Polyposis syndromes
18) History of inflammatory bowel disease: Crohn's Disease, Ulcerative Colitis
19) Chronic intestinal malabsorption syndromes: celiac sprue, bacterial overgrowth, chronic pancreatitis, pancreatic insufficiency
20) Previous gastrectomy, small bowel or large bowel resection
21) Malignancy, other than non-melanoma skin cancer
22) Severe lung disease – class 3 or 4 (COPD or emphysema requiring oxygen)
23) Severe heart disease: Cardiovascular disease functional class 3 or 4
24) Severe liver disease: Cirrhosis
25) HIV positive
26) Active hepatitis B or C
27) Use of chronic oral steroid therapy
28) Use of Lithium
29) Use of Phenytoins |