There are two forms of fiber: soluble and insoluble. Soluble fiber attracts water and turns to gel during digestion. This slows digestion and the rate of nutrient absorption from the stomach and intestine. It is found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables. Insoluble fiber is found in foods such as wheat bran, vegetables and whole grains. It appears to speed the passage of foods through the stomach. In either case, Fiber cannot be digested by humans. Thus, it has no calories because the body cannot absorb it. Dietary fiber provides a feeling of fullness and adds bulk in the diet. Fiber helps prevent constipation, and may be helpful in the prevention or treatment of diverticulosis and diabetes.