In this study, in order to investigate the effects of intake of BB536-y and FOS in preventing colorectal carcinogenesis, we examined the amounts of putrefactive bacteria, ETBF, and SCFA in fecal samples obtained from the BB536-y and BB536-y with FOS intake groups, and conducted culture of colon cancer cell lines in the presence of SCFA to study the cell-inhibitory effects of SCFA. The gene discussed is FOS; the disease is malignant colon neoplasm.