&NA;Two Turkish populations, one with an urban background and the other rural, were compared in regard to their colonic function. Rural subjects consume a diet with higher fiber than urban people in Turkey. The rural group had a greater daily fecal output, faster intestinal transit, and lower intraluminal pressure, with a greater output of calcium in the feces than those living in an urban area in Turkey. The effects are similar to those described when fiber is added to the diet. Urban dwellers in Turkey who lack these effects are said to have a rising incidence of fiber‐related diseases of the colon, such as diverticular disease.