Physiological small bowel malabsorption of carbohydrates protects against large bowel diseases in Africans.

In African black people there is a paucity of 'developed society' large bowel diseases such as diverticular disease, colorectal adenomas and carcinomas, ulcerative colitis and Crohn's disease. Appendicitis has an incidence of about 5-10% of the number likely to be observed in a white population. The conundrum is that the disparity exists despite many Africans having adopted an urbanized lifestyle with major changes in their dietary pattern. Dietary fiber intake, which was previously 30-35 g, has decreased to 12-14 g daily. Studies on small bowel function in black people have shown that physiological malabsorption of lactose, fructose, sucrose and maize (the staple food) occurs. It is hypothesized that the increased concentration of substrate available for fermentation in the colon compensates for the low dietary fiber intake, is protective to the large bowel and is a factor in the prevention of 'developed society' large bowel diseases in the African population.