Epidemiologists, on the basis of studies carried out chiefly in Africa, have suggested that depletion of fiber in the modern Western diet affects health adversely. D. P. Burkitt, who has been in the forefront of this investigation, has included among the "diseases of civilization" hiatus hernia, ischemic heart disease, cholelithiasis, polyps of the colon, and cancer of the colon. All of these conditions appear to have the same geographic distribution...