Fiber is the parts of plants that cannot be digested, namely complex carbohydrates, aka bulk or roughage. Complex carbohydrates from plants are rich in starch and fiber. Examples of plants that provide complex carbohydrates (fiber) are fresh fruits and vegetables, whole-grain breads, and cereal grains. Simple carbohydrates (e.g. table sugar), have no fiber. Dietary fiber can have many benefits including promoting bowel regularity, lowering cholesterol and easing hemorrhoids, colitis, and diverticulosis. Dietary fiber can also help in weight maintenance as it requires more chewing and promotes hunger satisfaction by giving the stomach a sense of fullness. It was once believed that all dietary fiber lowered the risk of colon cancer. Then in 1999 it was reported that dietary fiber seemed to have no effect on the chance of developing colon cancer. And in 2000 a kind of dietary fiber was discovered to increase the risk of the adenomas, the forerunners of cancer of the colon. The fiber under study was from ispaghula husk, which is not normally found in the diet but is found in laxatives containing mucilage. Ispaghula husk fiber is similar to psyllium, a fiber derived from plant husks that is found in many bulk laxatives. It appears that such laxatives should be avoided by anyone who may have colorectal adenomas. High fiber diets help delay the progression of diverticulosis and reduce the bouts of diverticulitis. In many cases, it helps reduce the symptoms of the Irritable Bowel Syndrome (IBS) (also called spastic colitis, mucus colitis, and nervous colon syndrome.) It is generally accepted that a diet high in fiber is protective, or at least reduces the incidence, of colon polyps and colon cancer. Soluble fibers (citrus, pears, oat bran, apples, peas/beans, psyllium, etc.) slow down the digestion of carbohydrates which results in better glucose metabolism. Some patients with the adult-onset diabetes may actually be successfully treated with a high-fiber diet alone, and those on insulin, can often reduce their insulin requirements by adhering to a high-fiber diet. Soluble fiber and insoluble fiber differ in function. For example, soluble fiber delays the time of transit through the intestine whereas insoluble fiber speeds up intestinal transit. For another example, soluble fiber and decreases the level of cholesterol in the blood whereas insoluble fiber has no effect on serum cholesterol. Oats, beans, dried peas, and legumes are major sources of soluble fiber whereas wheat bran, whole grain products, and vegetables are major sources of insoluble fiber. Fruits, vegetables, and barley are sources of both insoluble and soluble fiber.