Soluble and Insoluble Dietary Fiber
Generally speaking, fiber is not digested or absorbed, it tends to be resistant to digestion by intestinal enzymes.
Insoluble Fiber: Insoluble dietary fiber doesn't dissolve in water and passes through your digestive system largely unchanged. It is estimated that 65 to 75% of dietary fiber in our diet is "insoluble."
Insoluble fiber may be found in bran (the outer covering of corn, oats, rice, wheat), whole grains (corn, barley, rice, wheat, oats), cereals, edible skins of fruits and vegetables, celery, brown rice, and some vegetables.
Insoluble fiber accelerates intestinal transit, increases fecal weight, slows starch hydrolysis, and delays glucose absorption. This means softer, larger feces. It also results in an increased frequency of defecation. As the feces move through your intestine they scour intestinal walls and remove waste matter.
"Dietary fibre may play several roles relative to diabetes, including potential effects on satiety,obesity and the absorption of certain sugars. It is also believed that soluble fibre may slow digestion and absorption of carbohydrates, possibly helping to prevent wide swings in blood sugar levels. This could also be a factor in achieving a sense of fullness, especially when you consider that fibre may hamper the absorption of calorie-dense dietary fat, too".
Soluble Fiber: Soluble dietary fiber dissolves in water and is degraded by bacteria in your colon. The soluble fiber forms a gel-like consistency in water and is found in foods like beans, corn, oats, barley, peas, Brussels sprouts, lentils, carrots, cabbage, okra, apricots, prunes, dates, blackberries, cranberries, seeds, apples, bananas, citrus fruits, psyllium, certain gums and seaweed, to name a few.
Soluble fiber also increases stool volume and stool water content. It is believed that soluble fiber does this in a different manner than that done by insoluble fiber. Soluble dietary fiber forms a gel in your intestines which regulates the flow of waste material through your digestive tract. Soluble fiber slows stomach emptying time. This delays absorption of glucose from your blood stream(diabetics) and has been shown to lower cholesterol.
There is no dangerous side effect or reaction to dietary fiber; as long as adequate water is consumed. When fiber is increased, water must be increased.