Gel-forming soluble fibers are readily broken down by bacteria residing in the colon, as opposed to insoluble fibers, which are largely non-fermentable. Both have nutritional significance.
The water insoluble group such as cellulose and hemicellulose are found in the outer layers of whole grains, the strings of celery, the hulls of seeds and the skins of corn kernels. These fibers retain their structure and rough texture even after hours of cooking.
The water-soluble fibers such as those found in the brans of some cereals (e.g., oats and rice) and in pectin are believed to lower the levels of serum cholesterol by binding with bile acids and causing removal of cholesterol in the feces.
Dietary fiber exerts a wide range of physiological effects when consumed, and its complex nature is responsible for a range of physical and chemical properties that are responsible for these physiological effects.
Dietary fibers are now accepted to an important ingredient of a healthy diet, and are thought to reduce the probability of cancer induction in the digestive organs.
Dietary fibers shorten the time food remains in the digestive organs, and as a result a carcinogen will remain in contact with these organs for a shorter period.
The consumptions of fiber is recommended, although not to excess. It appears that excessive amounts of dietary fiber may interfere with the retention of minerals required by the body.
Fibers in food
