A low residue diet contains limited amounts of undigested or only partially digested ingredients. Residue is defined medically as the solid contents that have reached the lower intestine. The main source of residue is fiber in foods like whole grain breads and cereals, seeds and nuts, dried fruits, and the stalks and skins of fruits and vegetables. For good general health, a high-fiber diet is usually recommended.
Certain medical situations call for a low residue diet. People with acute diverticulitis and flares of inflammatory bowel disease (ulcerative colitis and Crohn's disease) are often prescribed low residue diets until the condition comes under control. Also, people with partial bowel obstructions generally have less abdominal discomfort with a very low residue diet.
Diet and residue can often be confusing for treatment of diverticula. Diverticula are outpouchings of the colon commonly seen as we get older. Most people don't know they have them until one of them becomes inflamed and infected (acute diverticulitis), or there is rectal bleeding. To prevent diverticula from forming, eat a high residue diet with plenty of fluids. But if you ever have diverticulitis, then switch to a low residue diet until you recover. Then switch back to the high-fiber routine.