EPIDEMIOLOGIC EVALUATION OF COLONIC DIVERTICULOSIS AND DIETARY FIBER IN JAPAN

The incidence of colonic diverticulosis was examined in 5 hospitals ge ographically isolated from each other in Japan during the period betwe en mid '70s and 1986. The incidence rapidly increased in all hospitals from 3.5-9.0% in mid '70s to 8.4-23.2% in 1986. The ratio of right-si ded type colonic diverticulosis was approximately 70-80% in each hospi tal and the ratio did not fluctuate significantly during the period. B irth cohort analysis revealed that although the incidence of right-sid ed diverticula had increased with aging, in groups born in more recent decades right-sided diverticula appeared in younger age than other gr oups. It was suggested that environmental factors rather than congenit al factors may cause the increase of the incidence of right-sided colo n diverticula.