Folate-Depleted Diet Compared With Folate-Supplemented Diet in Preventing Colorectal Cancer in Patients at High Risk for Colorectal Cancer

RATIONALE: Chemoprevention therapy is the use of certain agents to try to prevent the development of cancer. The use of folic acid may be effective in preventing colorectal cancer. Eating a diet rich in folic acid may prevent the development of colorectal cancer. PURPOSE: This randomized phase I trial is studying how well a folate-depleted diet works compared to a folate-supplemented diet in preventing colorectal cancer in patients who are at high risk for developing colorectal cancer.