There are two types of fiber: water-soluble and insoluble. Water-soluble fiber Water-soluble fiber dissolves in water and is found in oat bran, legumes, Psyllium , nuts, beans, pectins, and various fruits and vegetables. It forms a bulky gel in the intestine that regulates the flow of waste materials through the digestive tract. Water-soluble fiber may lower cholesterol by preventing the reabsorption of bile acids. Bile acids are made from cholesterol, and after they aid fat digestion, fiber binds with them and escorts them out of the body. The liver then has to pull more cholesterol from the blood. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Insoluble fiber Insoluble fiber cannot be dissolved in water, meaning that our bodies cannot digest it. This type of fiber includes the undissolvable parts of plant walls and is found in greatest amounts in cereals, brans, and vegetables. The primary function of insoluble fiber is to collect water that increases stool bulk in the large intestine. This promotes bowel movement, and as the bulk works through the intestine, it scours the intestinal walls of waste matter, reducing the risk of colon-related problems.