75–95% of colorectal cancer cases occur in people with little or no genetic risk. Risk factors include older age, male sex, high intake of fat, sugar, alcohol, red meat, processed meats, obesity, smoking, and a lack of physical exercise. Approximately 10% of cases are linked to insufficient activity. The risk from alcohol appears to increase at greater than one drink per day. Drinking 5 glasses of water a day is linked to a decrease in the risk of colorectal cancer and adenomatous polyps. Streptococcus gallolyticus is associated with colorectal cancer. Some strains of Streptococcus bovis/Streptococcus equinus complex are consumed by millions of people daily and thus may be safe. 25 to 80% of people with Streptococcus bovis/gallolyticus bacteremia have concomitant colorectal tumors. Seroprevalence of Streptococcus bovis/gallolyticus is considered as a candidate practical marker for the early prediction of an underlying bowel lesion at high risk population. It has been suggested that the presence of antibodies to Streptococcus bovis/gallolyticus antigens or the antigens themselves in the bloodstream may act as markers for the carcinogenesis in the colon.