Effect of dietary fiber on total carbohydrate losses in ileostomy effluent

Studies were performed in three ileostomate subjects to determine the effect of intake of various carbohydrate-containing foods on the ileostomy losses of macronutrients. The percent recovery of available carbohydrate in ileostomy effluent varied between 1.09% and 22.63% for the various foods. Available carbohydrate recovery (%) was positively correlated with fiber (r = 0.91) and protein (r = 0.46) intake, but negatively with available carbohydrate intake (r = -0.66). Stepwise regression indicated that dietary fiber intake was the principal factor determining the amount of available carbohydrate in ileostomy effluent. Fiber intake was negatively correlated with water concentration of the effluent (r = -0.61). This study demonstrates that although fiber has been considered the chief substrate available for colonic fermentation, as the fiber intake increases, so the total fermentable load entering the colon is likely to increase due to losses of available carbohydrates in addition to fiber. Simple assessment of dietary fiber is likely to grossly underestimate the fermentable load on high-fiber, high-carbohydrate diets.