The influence of phytic acid in wheat bran on early biomarkers of colon carcinogenesis.

A colon cancer protective effect of wheat bran has been observed in animal studies, but it is unclear whether the effect is due to fiber or other components, such as phytic acid (PA). Thus the objectives of this study were to determine if wheat bran alters early biomarkers of colon cancer risk, e.g. aberrant crypt foci (ACF) characteristics and indices of colonic cell proliferation, whether PA is the component responsible and whether there is a difference between endogenous and exogenously added PA. Five groups of azoxymethane-treated male Fischer 344 rats were fed for 100 days on a basal control diet (BD) or BD supplemented with either 25% wheat bran (WB), 25% dephytinized WB (DWB), 25% DWB plus 1.0% PA or 1.0% PA. All the WB-containing diets reduced the number of sialomucin-producing ACF and the degree of aberrant crypt luminal alterations in the whole colon. The WB and PA diets lowered the labeling index (LI) and the position of the uppermost labeled cell in the distal colon. Dephytinization caused an increase in the overall LI, LI in the top 40% and the position of the topmost labeled cell. Exogenous PA also reduced the number and size of ACF, the number of ACF per unit length colon as well as the number of sialomucin-producing ACF in various colon sections. It is concluded that WB, partly due to its endogenous PA, and exogenous PA when added to a low fiber diet can reduce early biomarkers of colon cancer risk.