Effect of Vitamin D and Calcium on Genes in the Colon

Inclusion Criteria:

1. Volunteers with a history of pre-cancerous colorectal polyps and/or have a family history of pre-cancerous polyps or colon cancer
2. Not taking any medications known to affect either calcium metabolism or colon function
3. Between the ages of 48 and 72 years old
4. Have had pre-cancerous colorectal polyps or have first or second degree relatives with colorectal cancer and are therefore at increased risk for the disease

Exclusion Criteria:

1. Personal history of cancer other than non-melanoma skin cancer
2. Diseases of the bowel such as intestinal malabsorption or inflammatory bowel disease
3. Prior gastrointestinal surgery including gastrectomy, small or large bowel resections. (If one has had an appendectomy or surgery of the esophagus, he/she is still eligible.)
4. Any excessive bleeding or clotting disorders
5. Taking blood thinners
6. Abnormalities of or conditions predisposing one to abnormalities of calcium metabolism. (This includes untreated hyperparathyroidism \[increase in parathyroid function\] and history of milk-alkali syndrome, a type of calcium metabolism disease.)
7. Untreated hyperthyroidism (increase in thyroid function)
8. Regularly take greater than 660 mg of aspirin per day. This is greater than two tablets of 325 mg regular strength aspirin or greater than one tablet of 500 mg of extra strength aspirin per day. (If one has been taking aspirin for heart or blood vessel protection regularly for at least one month before his/her first screening visit, he/she will remain on the same amount of medicine throughout the study. The following amounts are acceptable:

   * Aspirin 1 to 2 regular tablets (325 mg) per day, or
   * Baby aspirin 1 tablet (81 mg) per day
9. Regularly take daily dosages of nonsteroidal anti-inflammatory agents (NSAIDs) within the last 3 months. (One example of an NSAID is ibuprofen.)
10. Taking greater than 1200 mg of dietary calcium daily
11. Taking medications called sterol-binding resins, such as cholestyramine (Questran®), which is for the treatment of high blood cholesterol
12. Taking other investigational drugs or multiple other medications that might, in the opinion of the investigator, affect the study measurements.
13. Other serious illness(es) that are anticipated to limit life expectancy to less than 6 months
14. Elevated blood pressure greater than 160/100 mmHg
15. HIV positive
16. Pregnant or nursing
17. A history of kidney stones
18. Liver disease and/or kidney disease
19. Diabetes mellitus
20. High "bad" cholesterol level, low density lipoprotein (LDL) greater than 175 mg/dl or triglyceride levels greater than 600 mg/dl
21. Known history of coronary artery disease
22. EKG (electrocardiogram is a record of the electrical activity of the heart) changes consistent with a past heart attack (myocardial infraction)
23. Currently taking:

    * Antidiabetic medication
    * Hormone replacement therapies, oral, injected or implanted contraceptives. (Thyroid hormone replacement is allowed as long as one's thyroid test is normal.)
    * Vitamin, mineral, fish oil, and herbal supplementation and weight control medication must be stopped at least 1 month prior to enrolling in the study.