This study was designed with sixty 21-day old male Fisher 344 rats to investigate the preventive effect of the soypowder on colon cancer. The colon cancer was induced by injections with colon carcinogen 1,2-dimethylhydrazine (20 mg DMH/kg body weight/ time) at 4, 5, 6 and 7 weeks of age. All the rats were divided into control and experimental groups (n=15/group, soypowder (SP)). The rats were freely fed normal and experimental diets containing 5% soypowder for 8 weeks. On 8 weeks later all the rats were sacrificed. Body weight, food consumption weight, cecum pH, aberrant crypt (AC), aberrant crypt foc (ACF) were detected. Inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nitric oxide (NO) and histochemistry were analyzed. Body weight, food consumption, cecum pH did not differ among control and experimental groups. The number of AC and ACF in experimental groups was significantly lower than that of in control group (p＜0.05). The expression of iNOS and COX-2 in experimental groups was markedly lower than that of in control group. The concentration of NO in experimental group was significantly lower than that in control group (p＜0.05). Colon tissues were morphologically changed in control group showing damage in cell membrane and irregular arrangement of crypt. These results show that soypowder may inhibit colon carcinogenesis through diverse mechanism. Therefore, further study should be needed to identify the mechanisms by which soy powder may inhibit colon cancer.

Keywords: Soypowder, Colon, Carcinogenesis, 1,2-Dimethylhydrazine