Effects of transition on bowel diseases in sub-Saharan Africans.

In populations in sub-Saharan Africa, transitional changes in patterns of morbidity and mortality are taking place, with decreases in the diseases of poverty and infection, but rises in chronic diseases of prosperity, associated, however, with greater longevity. Remarkably, bowel diseases - appendicitis, diverticular disease, colon cancer - while nearly absent in rural areas, have very low incidences in urban dwellers, despite rises in risk factors, including a decreasing intake of fibre-containing foods. Currently, there is no explanation for the phenomenon, which stands in marked contrast to the considerable rises which have occurred in dental caries, obesity in women and diabetes.