Effects of brown rice, rice bran, and polished rice on colon carcinogenesis in rats

Rice is a nutritious staple food with health-promoting activity. This study investigated the effects of brown rice, rice bran, and polished rice on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. The colons were examined for preneoplastic lesions and the expression of pro-inflammatory proteins. Lipid peroxidation was determined in livers and plasma; antioxidant-associated parameters were determined in livers. The results showed that consumption of medium-level of rice bran significantly reduced the number of aberrant crypt foci (ACF) and altered their distribution. Brown rice and rice bran significantly reduced cyclooxygenase-2 (COX-2) expression of the middle colon. Brown rice, rice bran, and polished rice had no significant effect on plasma and hepatic lipid peroxides and hepatic antioxidant-associated parameters. Thus, rice bran may be one candidate of the active rice fraction that protects the colon against DMH-induced early carcinogenesis in rats and may be a novel dietary supplement for chemoprevention of colon cancer.