The effect of apple feeding on markers of colon carcinogenesis.

Regular consumption of fruits and vegetables is associated with reduced risks of certain cancers and other diseases in observational studies and animal models of human diseases. The aim of the present study was to investigate whether feeding of rats with whole raw apple has potentially chemopreventive properties by affecting markers of colon cancer. The end-point was preneoplastic changes in the colon known as aberrant crypt foci (ACF). Rats initiated with the colon carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were given 0, 5, or 10 g apple/day for 13 wk. The group fed 5 g apple but not 10 g had a significantly lower number of ACF (P = 0.009) compared to the initiated control. DNA damage evaluated by the comet assay was significantly increased in leucocytes of DMH-treated animals (P = 0.021). No antigenotoxic effect of apple feeding was apparent in the colon. Apple feeding tended to lower DNA damage in the liver (P = 0.136 in DMH-initiated and P = 0.284 in noninitiated rats). Liver alanine aminotransferase was significantly increased in rats fed apples (P = 0.008 in DMH-initiated and P = 0.019 in noninitiated rats). In conclusion, feeding whole fresh apple may affect the occurrence of preneoplastic changes in the rat colon, but the effect was not gradual.