AbstractColon cancer is the second most common type of cancer in the United States. Bile acids have been implicated in the etiology of this disease. In a previous study, we showed that bile acids can damage DNA in vitro. In this study, we report that this damage is largely prevented when the bile acids are pretreated with cellulose fiber. Preliminary data show that cellulose may act as a catalyst to promote polyesterification of bile acid to a biologically inactive form.