Effect of Folate on Colonic and Blood Cells

OBJECTIVES:

• To analyze the effects of changes in levels of dietary folate intake on damage to DNA and repair capacity, mRNA expression, and DNA uracil incorporation in peripheral blood mononuclear cell and rectal biopsy cell samples from patients at increased risk for developing colorectal neoplasia.

OUTLINE: Patients are enrolled into 1 of 2 intervention groups..

• Group I (folate depletion [in-patient]): Patients consume a weight-maintaining, average folate diet with no high folate-containing foods for 8 weeks. Patients are then admitted to The Rockefeller University Hospital and placed on a weight-maintaining, low-folate diet for 12 weeks. During the last 4 weeks of the in-patient period, patients receive oral folic acid supplementation once daily for 4 weeks.
• Group II (folate supplementation [out-patient]): Patients consume a weight-maintaining, average folate diet with no high folate-containing foods for 16 weeks as an out-patient. After the first 8 weeks of the diet, patients also receive oral folic acid supplementation once daily for 8 weeks.

Patients undergo blood sample collection periodically for biomarker correlative studies. Samples are analyzed for serum and red cell folate and homocystine levels to assess folate depletion; methylentetrahydrofolate reductase (MTHFR) polymorphism to test for inherited alterations of folate metabolism; serum and plasma biomarkers; and DNA studies. Patients also undergo tissue sample collection by sigmoidoscopy and rectal biopsy periodically. Tissue samples are assessed for mucosal folate concentration and mucosal folic acid metabolites; DNA methylation; and gene assays by microarray analysis.