The folate supplementation study requires an 8-week run-in period. During this run-in period, all participants will eat an average folate diet with no high folate containing foods. There are two screening visits during this period where initial blood-work is done and participants undergo nutritional consultation. Following the 8-week run-in period, subjects in the folate supplementation arm will be given a folate supplement for 8 weeks. During this entire time, subjects will continue to eat an average folate diet with no high folate containing foods. Blood samples and colorectal mucosa samples obtained during a sigmoidoscopy will be taken 3 times at 4 week intervals.