Intestinal absorption of nutrients is not influenced by soy fiber and does not differ between oligomeric and polymeric enteral diets.

Enteric feeding is often associated with diarrhea. To avoid this side effect, isoosmotic and fiber-supplemented enteral diets are recommended. The aims of this study were to determine whether supplementing enteral diets with soy fiber influences nutrient absorption and whether in enteric feeding absorption of nutrients and water fluxes differ between hyperosmotic oligomeric and isoosmotic polymeric diets. In mini pigs intestinal absorption and water fluxes were measured by perfusing a 150-cm length of jejunum. Six noncommercial iso- and hyperosmotic oligomeric and polymeric diets and six commercial polymeric diets, either fiber-free or supplemented with soy fiber, were used. Pancreatic enzymes were infused concomitantly with the polymeric diets. The absorption of nutrients and energy did not differ between oligomeric and polymeric diets. Oligomeric diets of high energy density produced a pronounced secretion of water. Despite lower initial osmolality, polymeric diets produced a similar secretion of water due to rapid pancreatic hydrolysis. Supplementing diets with largely insoluble soy fiber increased viscosity only between 4.6 and 14.5 mPa x sec. Soy fiber did not influence absorption of nutrients and energy and had also no effects on luminal transit and flow rate. The lack of effects was not due to dilution of chyme by intestinal secretion of water because no differences existed between isoosmotic and hyperosmotic oligomeric diets. In conclusion, supplementing enteral diets with soy fiber does not impair the absorption of nutrients. Enteric feeding with isoosmotic polymeric diets provides no advantage compared with hyperosmotic oligomeric diets with respect to absorption of nutrients and secretion of water.