Dietary risk factors thought to play a causative role in development of colorectal cancer include which of the following?

a. High fat intake

b. Low fiber intake

Evidence from epidemiological studies suggest that dietary factors play important causative roles in the development of large bowel cancers. From these studies, fat intake has been the most consistently positive association and fiber intake the most consistently inverse association noted in the incidence of colorectal cancer. In comparisons between countries, the rates of colon cancer are strongly associated with the intake of animal fat and meat. The associations between per capita consumption of total fat, saturated fat, and cholesterol and national incidence rates of colon cancer are strongly positive. The proposed mechanism by which dietary fat may increase the risk of developing colonic cancer is by its interaction with bile acids

The relation between fiber intake and colon cancer was initially noted by Burkitt, who reported low rates of colon cancer in areas of Africa where fiber consumption and stool bulk were high. In general, epidemiological studies have demonstrated that fiber intake is higher in non-western countries with lower incidence of colon cancer. The role of fiber was originally seen simply as providing bulk to dilute potential carcinogens and speed their transit through the colon. This appears to be an oversimplification and the relation between fiber intake and colon cancer is more complex. Additional studies have suggested that certain fibers may bind mutagens, which reduces their contact with colonic epithelium, may favorably change the fecal pH, and may participate in other complex interactions.