['In clinical studies, diminished folate availability appears to increase the risk for colorectal neoplasms. Additionally, alcohol and tobacco use are associated with an increased risk for colon cancer, but the early pathologic events by which these agents promote neoplastic transformation are not well understood. Aberrant crypt foci (ACF) are potential precursors of adenoma and cancer, and can be visualized by magnification endoscopy. We hypothesized that folate depletion is linked to ACF formation and therefore studied the association between tissue folate, dietary habits, and ACF number in patients undergoing screening colonoscopy.', 'Eighty-three patients, undergoing screening colonoscopy at an urban Veterans Affairs and university hospital, completed a questionnaire concerning alcohol, nonsteroidal anti-inflammatory drug (NSAID), and tobacco use. Folate intake was calculated from food frequency questionnaires. Rectal ACFs were scored using magnification chromoendoscopy (magnification, 35 x) by methylene blue staining. Folate concentrations in rectal biopsy specimens were determined by microtiter bioassay.', 'ACF number increased with age and with increasing tobacco intake. Decreased colonic folate level was associated with increased homocysteine levels and lower dietary folate intake but did not correlate with ACF number.'] Do relationship of aging and tobacco use with the development of aberrant crypt foci in a predominantly African-American population?