There is considerable current interest in the role of dietary fiber in the etiology of a number of diseases prevalent in the Western world. Prominent among those disease states whose prevalence is correlated with diets deficient in fiber is cancer of the large bowel. The high level of interest in the fiber hypothesis is due, in large part, to the epidemiologic observations of Burkitt and his colleagues1–3 who perceived that one factor common among diseases of the large bowel was a diet low in fiber. Drasar and Irving,4 on the other hand, correlated incidence of breast and colon cancer with a number of environmental factors and found a high positive correlation with total fat and animal protein, but practically none with dietary fiber (Table 15-1).