Effects of viscous dietary fibers on the digestive organs wereinvestigated in 5 week aged rats. Rats were fed the dietscontaining cellulose, pectin, tamarind gum or sodium alginate at4.78% as Prosky dietary fiber for 19 days. After feeding, weightsof digestive organs and activities of digestive enzymes in thepancreas and small intestinal mucosa were deterrnined.
1. The weight gains were lower in the groups fed viscous dietaryfibers compared with cellulose group, significantly lower in sodiumalginate group.
2. The weights of small intestine and cecum were significantlyhigher in the groups of viscous dietary fibers than the cellulosegroup. The stomach was significantly heavier in the sodium alginategroup and colon was significantly heavier in the pectin and sodiumalginate groups.
3. The protease activity in the pancreas was higher in the sodiumalginate group compared with other groups.
4. Disaccharidase activities in the .jejunal mucosa were lower inthe groups of viscous dietary flbers than in the cellulose group,whereas the disaccharidase activities in the duodenal mucosa weresimilar among the groups.
　 Our observations suggest that the viscosity of dietary fiber wasassociated with the enlargement of digestive organs and theincreased enzyme activity in the pancreas. However, anothermechanisms may play in the mucosal enzymes of small intestine.

Key words: viscous dietary fiber, disaccharidases, small intestinalmucosa, pancreas, digestive function