Tribromomethane exposure and dietary folate deficiency in the formation of aberrant crypt foci in the colons of F344/N rats.

Folate and folic acid are forms of the B vitamin that are involved in the synthesis, repair, and functioning of DNA and are required for the production and maintenance of cells. Low levels of folate have been associated with several forms of cancer, including colon cancer. Aberrant crypt foci (ACF), identified as putative precursor lesions in the development of colon cancer, have been induced by the drinking water disinfection by-product, tribromomethane (TBM). To investigate whether ACF induced by TBM could be promoted by a diet devoid of dietary folate, male F344/N rats were exposed to 500 mg/l of TBM in drinking water and fed either a normal or no folate diet (NFD) for 26 weeks. At the conclusion of the study, colons were excised and examined for ACF. Rats exposed to TBM and fed a NFD, evident by significantly reduced serum folate concentrations and elevated serum homocysteine levels, had significant increases of ACF when compared to rats exposed to TBM and fed a normal diet. This study highlights the important role that diet, especially folate intake, represents in protecting the colon against TBM-induced ACF.